Paleolithic diet

From Wikipedia, the free encyclopedia

Paleolithic-style dish: A traditional seafood stew (Bouillabaisse served without bread).

The Paleolithic diet (or Paleolithic nutrition), also popularly known as the paleo diet (paleodiet), caveman diet, Stone Age diet and hunter-gatherer diet, is a dietary regimen which emulates the diet of wild plants and animals that humans and their close relatives habitually consumed during the Paleolithic (the Old Stone Age), a period of about 2.5 million years duration that ended around 10,000 years ago when Homo sapiens developed agriculture.^[1] Based upon commonly available modern foods, the Paleolithic diet consists mainly of lean meat, fish, vegetables, fruit, roots and nuts, and excludes grains, legumes, dairy products, salt, refined sugar and processed oils.^[1][2]

First popularized in the mid 1970s by a gastroenterologist named Walter L. Voegtlin,^[3] this nutritional concept has been expounded and adapted by a number of authors and researchers in several books^[4][5][6] and academic journals.^[7] Building upon the principles of evolutionary medicine,^[8] it is based on the premise that modern humans are genetically adapted to the diet of their Paleolithic ancestors and that human genetics have scarcely changed since the dawn of agriculture, and therefore that an ideal diet for human health and well-being is one that resembles this ancestral diet.^[9][10]

This dietary approach is a controversial topic amongst nutritionists^[11][12] and anthropologists.^[13][14] Advocates argue that modern human populations subsisting on traditional diets similar to those of Paleolithic hunter-gatherers are largely free of diseases of affluence,^[15][16] and that such diets produce beneficial health outcomes in controlled medical studies.^[17] Supporters point to several potentially therapeutic nutritional characteristics of preagricultural diets.^[10] Critics of this nutritional approach have taken issue with its underlying evolutionary logic,^[18][19] and have disputed certain dietary prescriptions on the grounds that they pose health risks^[18][20] and may not reflect real Paleolithic diets.^[19][21] It has also been argued that such diets are not a realistic alternative for everyone,^[22] and that meat-based diets are not environmentally sustainable.^[23]

History

Gastroenterologist Walter L. Voegtlin was one of the first to suggest that following a diet similar to that of the Paleolithic era would improve a person's health. In 1975, he published a book^[3] in which he argued that humans are carnivorous animals and that the Paleolithic diet was that of a carnivore—chiefly fats and protein, with only small amounts of carbohydrates.^[24][25] His dietary prescriptions were based on his own medical treatments of various digestive problems, namely colitis, Crohn's disease, irritable bowel syndrome and indigestion.^[26]

In 1985, Melvin Konner and S. Boyd Eaton, an associate clinical professor of radiology and an adjunct associate professor of anthropology at Emory University, published a key paper on Paleolithic nutrition in the New England Journal of Medicine.^[7] Three years later, S. Boyd Eaton, Marjorie Shostak and Melvin Konner published a book about this nutritional approach,^[4] which was based on achieving the same proportions of nutrients (fat, protein, and carbohydrates, as well as vitamins and minerals) as were present in the diets of late Paleolithic people, not on excluding foods that were not available before the development of agriculture. As such, this nutritional approach included skimmed milk, whole-grain bread, brown rice, and potatoes prepared without fat, on the premise that such foods have the same nutritional properties as Paleolithic foods.^[24][27] In 1989, these authors published a second book on Paleolithic nutrition.^[28][29]

Since the end of the 1990s, a number of medical doctors and nutritionists^[30][31][32] have started to advocate a return to a so-called Paleolithic (pre-agricultural) diet.^[14] Proponents of this nutritional approach have published books^[5][6][33] and created websites^[34][35] to promote their dietary prescriptions.^{[36][37][38][39][40]} They have synthesized diets from commonly available modern foods that would emulate the nutritional characteristics of the ancestral Paleolithic diet, some allowing specific foods that would have been unavailable to preagricultural peoples, such as certain processed oils and beverages.^{[5][6][41][34][42]}

[edit] Practices

Paleolithic-style dish: A raw tomato sauce with olives, celery, spinach and walnuts on courgette 'pasta' noodles.

The Paleolithic diet is a modern dietary regimen that seeks to mimic the dietary practices of Paleolithic hunter-gatherers.^[1] Based upon commonly available modern foods, it includes cultivated plants and domesticated animal meat as an alternative to the wild sources of the original preagricultural diet.^[1][2][43] The ancestral human diet is inferred from historical and ethnographic studies of modern-day hunter-gatherers as well as archaeological finds and anthropological evidence.^[10][44][45]

The Paleolithic diet consists of foods that can be hunted and fished, such as meat, offal and seafood, and that can be gathered, such as eggs, insects, fruit, nuts, seeds, vegetables, mushrooms, herbs and spices.^[1][2] Practitioners are advised to eat only the leanest cuts of meat, free of food additives, preferably wild game meats, such as quail, rabbit, and venison, as well as grass-fed beef, since they contain relatively high levels of omega-3 fats compared with grain-produced domestic meats.^{[1][2][43][46]} Food groups that were rarely or never consumed by humans before the Neolithic revolution are excluded from the diet, mainly grains, legumes (e.g. peanuts), dairy products, salt, refined sugar and processed oils,^[1][2] although some advocates consider the use of oils with low omega-6/omega-3 ratios, such as olive oil and canola oil, to be healthy and advisable.^[43] Practitioners are permitted to drink mainly water, and some advocates recommend tea as a healthful drink,^[43] but alcoholic and fermented beverages are restricted from the diet.^[2][43] Furthermore, eating a wide variety of plant foods is recommended to avoid high intakes of potentially harmful bioactive substances, such as goitrogens, which are present in certain roots, vegetables and seeds.^[1][44][47] Unlike raw food diets, the Paleolithic diet does not limit the consumption of cooked foods.^[1] Cooking is widely accepted to have been practised by at least 250,000 years ago, in the Middle Paleolithic.^[48]

Loren Cordain, a professor in the Department of Health and Exercise Science at Colorado State University, recommends that practitioners derive about 56–65% of their food energy from animal foods and 36–45% from plant foods. He advocates a diet high in protein (19–35% energy) and relatively low in carbohydrates (22–40% energy), with a fat intake (28–58% energy) similar to or higher than that found in Western diets.^[43][49][50] Moreover, according to Cordain, root vegetables that exhibit high glycemic indices, such as potatoes, should be excluded from the diet.^[2] Staffan Lindeberg, an associate professor in the Department of Medicine at the University of Lund, advocates a Paleolithic diet without recommending any particular proportions of plants versus meat or macronutrient ratios.^[1][44] According to Lindeberg, calcium supplementation may be considered when the intake of green leafy vegetables and other dietary sources of calcium is limited.^[1]

Scientific basis

Over 70% of our dietary calories come from foods that our Paleolithic ancestors rarely, if ever, ate, such as grains, dairy products and cooking oils.^[10] (USDA's Food Pyramid)

According to S. Boyd Eaton, "we are the heirs of inherited characteristics accrued over millions of years; the vast majority of our biochemistry and physiology are tuned to life conditions that existed prior to the advent of agriculture some 10,000 years ago. Genetically our bodies are virtually the same as they were at the end of the Paleolithic Era some 20,000 years ago."^[51]

Paleolithic nutrition has its roots in evolutionary biology and rests on the principles of evolutionary medicine.^[8][52] The reasoning underlying this nutritional approach is that natural selection had sufficient time to genetically adapt the metabolism and physiology of the various human species living during the Paleolithic to the varying dietary conditions of that era. But in the 10,000 years since the invention of agriculture and its consequent major change in the human diet, natural selection has had too little time to make the optimal genetic adaptations to the new diet.^[1] Physiological and metabolic maladaptations result from the suboptimal genetic adaptations to the contemporary human diet, which in turn contribute to many of the so-called diseases of civilization.^[9]

Loren Cordain argues that "today more than 70% of our dietary calories come from foods that our Paleolithic (Stone Age) ancestors rarely, if ever, ate. The result is epidemic levels of cardiovascular disease, cancer, diabetes, osteoporosis, arthritis, gastrointestinal disease, acne, and more."^[35] According to Staffan Lindeberg, the "Paleolithic diet", basically meat, fish, vegetables, fruit and nuts, prevents heart disease, stroke and some forms of cancers and it has a beneficial effect on overweight, digestive problems and more;^[34] it may have benefits even compared with prudent diets based on whole-grain cereals and low-fat milk.^[53]

Interpretation of medical research

Based on the subsistence patterns and biomarkers of hunter-gatherers studied in the last century, advocates argue that modern humans are well adapted to the diet of their Paleolithic ancestors.^[54] The diet of modern hunter-gatherer groups is believed to be representative of patterns for humans of 50 to 25 thousand years ago,^[54] and individuals from these and other technologically primitive societies,^[55][56] including those individuals who reach the age of 60 or beyond, seem to be largely free of the signs and symptoms of chronic disease (such as obesity, high blood pressure, nonobstructive coronary atherosclerosis, and insulin resistance)^[B] that universally afflict the elderly in western societies (with the exception of osteoarthritis, which afflicts both populations).Moreover, when these people adopt western diets, their health declines and they begin to exhibit signs and symptoms of "diseases of civilization".^[15][54] In one clinical study, stroke and ischaemic heart disease appeared to be absent in a population living on the island of Kitava, in Papua New Guinea, where a subsistence lifestyle, uninfluenced by western dietary habits, was still maintained.

The results of controlled medical studies on the Paleolithic diet have also been interpreted as evidence of the health benefits of such diets.^[60][61][62] The first animal experiment on a Paleolithic diet suggested that this diet, as compared with a cereal-based diet, conferred higher insulin sensitivity, lower C-reactive protein and lower blood pressure in domestic pigs.^[62] Subsequently, a short-term intervention with such a diet in healthy volunteers showed some favourable effects on cardiovascular risk factors.^[63] In the first controlled human trial on a Paleolithic diet, researchers found that the diet improved glucose tolerance more than a Mediterranean diet in individuals with ischaemic heart disease.^[17]

Nutritional factors

The novel foods introduced as staples during the Neolithic and Industrial Eras, namely dairy products, beans, cereals, refined cereals, refined sugars, refined vegetable oils, alcohol, salt and fatty domestic meats,^[C] are believed to have fundamentally altered several key nutritional characteristics of the human diet since the Paleolithic period, and these dietary compositional changes have been implicated as risk factors in the pathogenesis of many of the so-called "diseases of civilization",^{[9][10][64][65]} including obesity, cardiovascular disease,^[66] diabetes, osteoporosis,^[67][68] autoimmune-related diseases,^[69] certain cancers,^[70][71] and acne, as well as many diseases related to vitamin and mineral deficiencies.

According to Cordain et al., seven crucial nutritional characteristics of ancestral hominin diets that have been fundamentally altered by food staples and food-processing procedures introduced during the Neolithic and Industrial Periods serve to inhibit the development of diseases of affluence in modern-day hunter-gatherers:

• Glycemic load: Unrefined wild plant foods like those available to contemporary hunter-gatherers typically exhibit low glycemic indices.^[77] Moreover, their diets are devoid of dairy products, such as milk, yoghurt, and cottage cheese, which have low glycemic indices, but are highly insulinotropic, with an insulin index similar to that of white bread.^[78][79] These dietary characteristics may lower risk of diabetes, obesity and other related syndrome X diseases by placing less stress on the pancreas to produce insulin, and preventing insulin insensitivity.^[80]

• Fatty acid composition: Hunter-gatherer diets generally maintain relatively high levels of monounsaturated and polyunsaturated fats, moderately low levels of saturated fats (10–15% of total food energy^[81]) as well as a low omega-6:omega-3 fatty acid ratio. Moreover, they are devoid of artificial trans fat. These nutritional factors may serve to inhibit the development of cardiovascular disease.^[10]

• Macronutrient composition: Dietary protein is characteristically elevated (19–35% of energy) at the expense of carbohydrate (22–40% of energy).^[49][50] High protein diets may have a cardiovascular protective effect and may represent an effective weight loss strategy for the overweight or obese.^[10] Furthermore, carbohydrate restriction may help prevent obesity and type 2 diabetes,^[82][83] as well as atherosclerosis.^[66]

• Micronutrient density: Fruits, vegetables, lean meats, and seafood, which are staples of the hunter-gatherer diet, are more nutrient-dense than refined sugars, grains, vegetable oils, and dairy products. Consequently, the vitamin and mineral content of the diet is very high compared with a standard diet, in many cases a multiple of the RDA.^[2]

• Acid-base balance: Because of the absence of cereals and energy-dense, nutrient-poor foods, foods that displace base-yielding fruits and vegetables, the diet produces a net base load on the body, as opposed to a net acid load. Net acid producing diets may contribute to the development of osteoporosis and renal stones, loss of muscle mass, and age-related renal insufficiency.^[67][84]

• Sodium-potassium ratio: Since no processed foods or added salt are included the sodium intake (~726 mg) is lower than average U.S. values (3,271 mg) or recommended values (2,400 mg). Further, since potassium-rich fruits and vegetables comprise ~30% of the daily energy, the potassium content (~9,062 mg) is nearly 3.5 times greater than average values (2,620 mg) in the U.S. diet.^[2] Diets containing high amounts of salt induce and sustain increased acidity of body fluid, which may contribute to the development of osteoporosis and renal stones, loss of muscle mass, and age-related renal insufficiency. Moreover, the inverted ratio of potassium to sodium in the U.S. diet compared with preagricultural diets adversely affects cardiovascular function and contributes to hypertension and stroke

• Fiber content: Contemporary diets devoid of cereal grains, dairy products, refined oils and sugars, and processed foods have been shown to contain significantly more fiber (~42.5 g/d) than either current or recommended values.^[2]

Objections to the Paleolithic diet

Comparative life expectancy

One of the most frequent criticisms of this nutritional approach is that it is unlikely that Paleolithic hunter-gatherers suffered from the diseases of modern civilization simply because they did not live long enough to develop these illnesses, which are typically associated with old age.^{[12][16][86][87][88]} Advocates state in response that human populations with lifestyles resembling that of our pre-agricultural ancestors have no or little diseases of affluence, despite sufficient numbers of elderly.^[16][89]

Criticism of evolutionary logic

The evolutionary assumptions upon which the Paleolithic diet is based have been disputed.^[13][19][27] According to Alexander Ströhle, Maike Wolters and Andreas Hahn,^[19] with the Department of Food Science at the University of Hannover, the statement that the human genome evolved during the Pleistocene (a period from 1,808,000 to 11,550 years ago) is resting on an inadequate, but popular gene-centered view of evolution. They argue that evolution of organisms cannot be reduced to the genetic level with reference to mutation and that there is no one to one relationship between genotype and phenotype.

They further question the notion that 10,000 years since the dawn of agriculture is a period not nearly sufficient to ensure an adequate adaptation to agrarian diets. Ströhle et al. argue that the number of generations that a species existed in the old environment is irrelevant, and that the response to the change of the environment of a species would depend on the hereditability of the traits, the intensity of selection and the number of generations that selection acts. They state that if the diet of Neolithic agriculturalists had been in discordance with their physiology, then this would have created a selection pressure for evolutionary change and modern humans, such as Europeans, whose ancestors have subsisted on agrarian diets for 400–500 generations should be somehow adequately adapted to it. In response to this argument, Wolfgang Kopp states that "we have to take into account that death from atherosclerosis and cardiovascular disease (CVD) occurs later during life, as a rule after the reproduction phase. Even a high mortality from CVD after the reproduction phase will create little selection pressure. Thus, it seems that a diet can be functional (it keeps us going) and dysfunctional (it causes health problems) at the same time."Moreover, S. Boyd Eaton and colleagues have indicated that "comparative genetic data provide compelling evidence against the contention that long exposure to agricultural and industrial circumstances has distanced us, genetically, from our Stone Age ancestors."^[According to Kopp, the implementation of high-glycemic and high-insulinogenic food, like refined cereals and sugars, into human nutrition only about 200 years, or 10 generations, ago, occurred too recently on an evolutionary time scale for the human genome to adjust.

According to Ströhle et al. "whatever is the fact, to think that a dietary factor is valuable (functional) to the organism only when there was ‘genetical adaptation’ and hence a new dietary factor is dysfunctional per se because there was no evolutionary adaptation to it, such a panselectionist misreading of biological evolution seems to be inspired by a naive adaptationistic view of life."

No evidence of adaptation to Paleolithic diets

Katharine Milton, a professor of physical anthropology at the University of California, has also disputed the evolutionary logic upon which is based the Paleolithic diet. She questions the premise that the metabolism of modern humans must be genetically adapted to the dietary conditions of the Paleolithic.^[13] According to Milton,^[13] "there is little evidence to suggest that human nutritional requirements or human digestive physiology were significantly affected by such diets at any point in human evolution."^{[95][96][97][98]}

Food energy excess causes diseases of affluence

According to Geoffrey Cannon, science and health policy advisor to the World Cancer Research Fund, humans are designed to work physically hard to produce food for subsistence and to survive periods of acute food shortage, and are not adapted to a diet rich in energy-dense foods.^[99] These are, in his view, the crucial evolutionary principles that underly the diseases of affluence. Similarly, William R. Leonard, a professor of anthropology at Northwestern University, states that the health problems facing industrial societies stem not from deviations from a specific ancestral diet but from an imbalance between calories consumed and calories burned, a state of energy excess uncharacteristic of ancestral lifestyles.^[100]

Objections to low-carbohydrate and high-protein versions

The high protein and low-carbohydrate diet^[A] recommended by Loren Cordain and colleagues based on worldwide modern hunter-gatherer diets has attracted a number of criticisms, including the following:

No superior therapeutic merits

It has been argued that relative freedom from degenerative diseases was, and still is, characteristic of all hunter-gatherer societies irrespective of the macronutrient characteristics of their diets. Katharine Milton states that "hunter-gatherer societies, both recent and ancestral, displayed a wide variety of plant-animal subsistence ratios, illustrating the adaptability of human metabolism to a broad range of energy substrates. Because all hunter-gatherer societies are largely free of chronic degenerative disease, there seems little justification for advocating the therapeutic merits of one type of hunter-gatherer diet over another."

Marion Nestle, a professor in the Department of Nutrition and Food Studies at New York University, states that based on research relating nutritional factors to chronic disease risks, and to observations of exceptionally low chronic disease rates among people eating vegetarian, Mediterranean and Asian diets, plant-based diets are most associated with health and longevity.

According to Ströhle, Wolters and Hahn,^[19] hunters like the Inuit, who traditionally obtain most of their dietary energy from wild animals and therefore eat a low-carbohydrate diet,seem to have a high mortality from coronary heart disease and many populations of horticulturists, pastoralists and simple agriculturists living today are ingesting a high-carbohydrate diet without having signs and symptoms of CHD.In response to this criticism, Wolfgang Kopp states that "carbohydrate food, consumed by hunter-gatherers, is high in fiber and low-glycemic in effect, eliciting small amounts of insulin only. [...] Are high-carbohydrate diets atherogenic per se? Not if they have a low glycemic load. In this point, Stroehle et al. are right. However, it is the question, whether diets high in low-glycemic plant food (which is relatively high in indigestible fiber and relatively low in carbohydrate) should be labeled as “high-carbohydrate” diets." Kopp also says that it is very likely that diets with only a moderately increased glycemic load are atherogenic to some degree.

At odds with evidence of Paleolithic diets

It has also been argued that there are insufficient data to identify the relative proportions of animal and plant foods in the diets of Paleolithic humans.

Furthermore, according to Katharine Milton, "data from ethnographic studies of nineteenth and twentieth century hunter-gatherers, as well as historical accounts and the archeological record, suggest that ancestral hunter-gatherers enjoyed a rich variety of different diets. Thus estimates of nutrient proportions for "the Paleolithic diet" are hypothetical, at best."Echoing Milton's criticism, Ströhle et al.^[19] argue that it is questionable if all hunter-gatherers living between 150,000 and 10,000 years ago in different geographical regions ate a low-carbohydrate diet.^[ They indicate that, because the plant–animal subsistence ratios of contemporary hunter-gatherers vary in a remarkable manner (0–90% food from gathering; 10–100% food from hunting and fishing), it is likely that the macronutrient intake of preagricultural humans varied enormously.

They also refer to a hypothesis (the 'Plant underground storage organs hypotheses') that suggests that carbohydrate tubers were eaten in high amounts by our preagricultural ancestors.^{[113][119][120][121]} They add: "Provided that humans are incapable of metabolizing high amounts of dietary protein and given the fact that wild African mammals are relatively low in fat, a diet supplemented with carbohydrates from tubers seems to be more efficient in meeting the energy requirements of early hunters and gatherers than a diet based on lean meat."

Ströhle et al. further mention that Staffan Lindeberg, an advocate of a "Paleolithic diet", has accounted for a plant-based diet rich in carbohydrates as being consistent with the human evolutionary past.

Comparative life expectancy

According to Geoffrey Cannon, "relatively carnivorous diets high in fat, and extremely high in protein evolved with physically very active populations who usually did not live long enough to suffer from chronic diseases. This does not mean us." In response to this argument, S. Boyd Eaton and colleagues state that while Paleolithic humans did have a shorter average life expectancy than we do, studies of modern hunter-gatherer populations suggest that ancestral foragers that reached the age of 60 or beyond were almost completely free from manifestations of most chronic degenerative diseases.

Possible contraindications

According to Erica Frank, professor of health care at the University of British Columbia, eating an animal also involves absorbing the toxins stored in its body fat. She quotes the EPA: "The average American intake is between 300 and 500 times the safe daily dose of dioxin."She argues that dioxin, which is stored in animal fat, is a cancer-causing substance and disrupts hormones and the immune system. "People would be in error if they think they're doing themselves a service by eating bison."

Sustainability concerns

The Paleolithic diet has been criticized on the grounds that it cannot be implemented on a worldwide scale. According to Loren Cordain, if such a diet was widely adopted, it would compromise the food security of populations dependent on cereal grains for their subsistence. However, he says that where cereals are not a necessity, as in most western countries, reverting to a grain-free diet can be highly practical in terms of cutting long-term healthcare costs. Barry Bogin, a professor of anthropology at the University of Michigan, argues that less intensive farming techniques, such as pasture-grazed cattle, will not produce sufficient meat to feed the world’s population.

Concerns have also been raised about the detrimental effects of meat-based diets on the environment.According to Anthony J. McMichael, director of the National Centre for Epidemiology and Population Health at the Australian National University, "in order to achieve a world nutritional state that is health-supporting, equitable and ecologically sustainable, we can learn much from consideration of the interplay between the evolutionary, environmental and ecological realms." He further indicates that the level of per-person meat consumption need only be moderate for dietary optimisation in accordance with human evolutionary biology.

Healthy diet

From Wikipedia, the free encyclopedia

A healthy diet is the practice of making choices about what to eat with the intent of improving or maintaining good health. This usually involves consuming nutrients by eating the appropriate amounts from all of the food groups, including an adequate amount of water. Since human nutrition is complex, a healthy diet may vary widely, and is subject to an individual's genetic makeup, environment, and health. For around 20% of the human population, lack of food and malnutrition are the main impediments to healthy eating.^{[citation needed]} Conversely, people in developed countries have the opposite problem; they are more concerned about obesity.^{[citation needed]}

Nutritional overview

Generally, a healthy diet is said to include:

1. Sufficient calories to maintain a person's metabolic and activity needs, but not so excessive as to result in fat storage greater than roughly 30% of body mass. 2,000 is the recommended daily allowance of calories for most people, but it depends on age, gender, height, and weight. (see Body fat percentage)
2. Sufficient quantities of fat, including monounsaturated fat, polyunsaturated fat and saturated fat, with a balance of omega-6 and long-chain omega-3 lipids. 65 grams is the recommended daily allowance of fat.
3. Maintenance of a good ratio between carbohydrates and lipids (4:1): four grams of the first for one gram of the second.
4. Avoidance of excessive saturated fat (although the "evidence" for this claim is forever in debate after the testimony of results provided by the Framingham Heart Study of 1948-1998)
5. Avoidance of trans fat.
6. Sufficient essential amino acids ("complete protein") to provide cellular replenishment and transport proteins. (All essential amino acids are present in animals. Some plants together give all the essential acids ex. rice and beans which have limitations.)
7. Essential micronutrients such as vitamins and certain minerals.
8. Avoiding directly poisonous (e.g. heavy metals) and carcinogenic (e.g. benzene) substances;
9. Avoiding foods contaminated by human pathogens (e.g. e.coli, tapeworm eggs);
10. Avoiding chronic high doses of certain foods that are benign or beneficial in small or occasional doses, such as
    • foods or substances with directly toxic properties at high chronic doses (e.g. ethyl alcohol);
    • foods that may interfere at high doses with other body processes (e.g. refined table salt);
    • foods that may burden or exhaust normal functions (e.g. refined carbohydrates without adequate dietary fibre).

Governmental guidance

People eat foods and not nutrients; as few people know which foods supply which nutrients, allowing people to self-regulate their diets means that they run the obvious risk of deficiency. Due to past difficulties of educating people about nutrient intake, governments have opted to counsel on what foods to eat rather than on what nutrients to ingest.

Most states set guidelines for a healthy diet -- these usually vary slightly from country to country based upon demographics. These guidelines do however usually share the same recommendations of eating less fried or fatty foods to reduce cholesterol. Many guidelines suggest replacing certain foods with healthier alternatives that supply an abundance of nutrients, for instance using legumes or beans within a salad or pasta.

As BMI and weight changes from person to person, the general Reference Nutrient Intakes (RNI) set by governmental institutions may be somewhat lacking for some people, despite the fact that the RNI is generally calculated as higher than the average nutrient intake. It is even thought^[who?] that some people may have needs above that of the RNI, meaning even if a person ate the recommended amount of nutrients, they would still suffer deficiency. The only real way to know the RNI for many people is to monitor the intake of nutrients and amount of exercise.

Examples of specific recommendations include:

• The Dietary Reference Intake system, used to set recommended amounts of various nutrients on food labels in the United States and Canada.
• MyPyramid, formerly food guide pyramid, a graphical recommendation from the United States Department of Agriculture.
• Canada's Food Guide

Some groups have been critical of the U.S. pyramids, alleging poor scientific basis, and influence from food producers. Harvard School of Public Health researchers have proposed their own healthy eating pyramid.

A high-level summary of Government Guidance is:

• Make sure that you eat five different types of fruit and vegetables every day. Every day also make sure that you eat at least one thing from each of the different food groups: Carbohydrates, Fruit and vegetables, Protein, Dairy, and Fats. Remember to eat the most fruit and vegetables, and the least fats.

• Too much salt gives you high blood pressure; a high fat diet will give you hard and narrow arteries that could lead to heart attacks and strokes, possibly even death.

• Fruit and vegetables contain antioxidants which will keep you healthy as long as you team them up with regular daily exercise. Your efforts to eat healthily will go to waste if you do not take part in regular daily exercise.

• Having fiber in your diet will keep your digestive system going strong.

Detrimental eating habits

In specific individuals, ingesting foods containing natural allergens (e.g. peanuts, shellfood) or drug-induced triggers (e.g. tyramine for a person taking an MAO inhibitor) may be life-threatening.

Some foods have low nutritional value, and if consumed on a regular basis will contribute to the decline of human health. This has been demonstrated by various epidemiological studies that have determined that foods such as processed and fast foods are linked to diabetes and various heart problems.

When improperly cut or prepared, a small number of foods (such as fugu) can result in death.

The ingredient usually cited as being most crucial to good health, water, has even been known to result in death when consumed in extraordinary quantities.

Cultural and psychological factors

From a psychological perspective, a new healthy diet may be difficult to achieve for a person with poor eating habits. This may be due to tastes acquired in early adolescence and preferences for fatty foods. It may be easier for such a person to transition to a healthy diet if treats such as chocolate are allowed; sweets may act as mood stabilizers, which could help reinforce correct nutrient intake.

It is known that the experiences we have in childhood relating to consumption of food affect our perspective on food consumption in later life. From this, we are able to determine ourselves our limits of how much we will eat, as well as foods we will not eat - which can develop into eating disorders, such as anorexia, bulimia, or orthorexia This is also true with how we perceive the sizes of the meals or amounts of food we consume daily; people have different interpretations of small and large meals based on upbringing.

While plants, vegetables, and fruits are known to help reduce the incidence of chronic disease, the benefits on health posed by plant-based foods, as well as the percentage of which a diet needs to be plant based in order to have health benefits is unknown. Nevertheless, plant-based food diets in society and between nutritionist circles are linked to health and longevity, as well as contributing to lowering cholesterol, weight loss, and in some cases, stress reduction.

Indeed, ideas of what counts as "healthy eating" have varied in different times and places, according to scientific advances in the field of nutrition, cultural fashions, religious proscriptions, or personal considerations.

Public policy issues

Fears of high cholesterol were frequently voiced up until the mid-1990s. However, more recent research has shown that the distinction between high- and low-density lipoprotein ('good' and 'bad' cholesterol, respectively) must be addressed when speaking of the potential ill effects of cholesterol. Low-density lipoprotein is often prevalent in animal products, such as bacon and egg yolks, whereas high-density lipoprotein is more common in plant and fish tissues, such as olive oil and salmon.

Media coverage of mass-produced, processed, "snack" or "sweet" products directly marketed at children has worked to undermine policy efforts to improve eating habits. The main problem with such advertisements for foods is that alcohol and fast food are portrayed as offering excitement, escape and instant gratification.

Particularly within the last five years government agencies have attempted to combat the amount and method of media coverage lavished upon "junk" foods. Governments also put pressure on businesses to promote healthy food options, consider limiting the availability of junk food in state-run schools, and tax foods that are high in fat. Most recently, the United Kingdom removed the rights for McDonald's to advertise its products as the majority of the foods that were seen to have low nutrient values were aimed at children under the guise of the "Happy Meal". The British Heart Foundation released its own government-funded advertisements, labeled "Food4Thought," which were targeted at children and adults displaying the gory nature of how fast food is generally constituted.

Low-carbohydrate diet

From Wikipedia, the free encyclopedia

Low-carbohydrate diets or low-carb diets are dietary programs that restrict carbohydrate consumption usually for weight control. Foods high in digestible carbohydrates are limited or replaced with foods containing a higher percentage of proteins and fats.

The precise definition of low-carbohydrate diets varies greatly. The term is most commonly used to refer to ketogenic diets, i.e. diets that restrict carbohydrate intake sufficiently to cause ketosis like the Atkins diet, but some sources consider less restrictive variants to be low-carbohydrate as well.

Apart from obesity low-carbohydrate diets are often discussed as treatments for some other conditions, most notably diabetes and epilepsy, although these treatments still remain controversial and lack widespread support.

History

Beginnings

In 1863 William Banting, an obese English undertaker and coffin maker, published "Letter on Corpulence Addressed to the Public" in which he described a diet for weight control giving up bread, butter, milk, sugar, beer and potatoes. His booklet was widely read, so much so that some people used the term "Banting" for the activity usually called "dieting."

In 1967, Dr. Irwin Stillman published The Doctor's Quick Weight Loss Diet. The "Stillman Diet" is a high-protein, low-carbohydrate and low-fat diet. It is regarded as one of the first low-carbohydrate diets to become popular in the US. Other low-carbohydrate diets in the 1960's included Air Force Diet^[ and the Drinking Man’s Diet Austrian physician Dr Wolfgang Lutz published his book 'Leben Ohne Brot' (Life Without Bread) in 1967.However it was hardly noticed in the English speaking world.

In 1972, Dr. Robert Atkins published Dr. Atkins Diet Revolution which advocated a low-carbohydrate diet he had successfully used in treating patients in the 1960s (having himself developed the diet from an unspecified article published in JAMA)The book met with some success but, because of research at that time suggesting risk factors associated with excess fat and protein, it was widely criticized by the mainstream medical community as being dangerous and misleading, thereby limiting its appeal at the time. Among other things critics pointed out that Dr. Atkins had done little real research into his theories and based them mostly on anecdotal evidence.

The concept of the glycemic index was invented in 1981 by Dr. David Jenkins. This concept evaluates foods according to their insulin demand -- with fast digesting simple carbohydrates having a high insulin demand and slower digesting complex carbohydrates such as grains having a lower insulin demand

Low carb craze

In the 1990s Dr. Atkins published Dr. Atkins New Diet Revolution and other doctors began to publish books based on the same principles. This has been said to be the beginning of the "low carb craze."During the late 1990s and early 2000s low-carbohydrate diets became some of the most popular diets in the U.S. (by some accounts as much as 18% of the population was using a low-carbohydrate diet at its peak and spread to many countries. These were, in fact, noted by some food manufacturers and restaurant chains as substantially affecting their businesses (notably Krispy Kreme^[22]). This was in spite of the fact that the mainstream medical community continued to denounce low-carbohydrate diets as being a dangerous trend. It is, however, valuable to note that many of these same doctors and institutions at the same time quietly began altering their own advice to be closer to the low-carbohydrate recommendations (e.g. eating more protein, eating more fiber/less starch, reducing consumption of juices by children) The low-carbohydrate advocates did some adjustments of their own increasingly advocating controlling fat and eliminating trans fat. Many of the diet guides and gurus that appeared at this time intentionally distanced themselves from Atkins and the term low carb (because of the controversies) even though their recommendations were based on largely the same principles (e.g. the Zone diet). As such it is often a matter of debate which diets are really low-carbohydrate and which are not. The 1990s and 2000s also saw the publication of an increased number of clinical studies regarding the effectiveness and safety (pro and con) of low-carbohydrate diets (notably a 2006 NEJM paper by Halton et al. describing a 20-year study).

After 2004 the popularity of this diet trend began to wane significantly although it still remains quite popular. In spite of the decline in popuarlity this diet trend has continued to quietly garner attention in the medical and nutritional science communities.

Practices and theories

The term low-carbohydrate diet today is most strongly associated with the Atkins Diet. However, there is an array of other diets that share to varying degrees the same principles (e.g. the Zone Diet, the Protein Power Lifeplan, and the South Beach Diet). Therefore, there is no widely accepted definition of what precisely consistutes a low-carbohydrate diet. It is important to note that the level of carbohydrate consumption defined as low-carbohydrate by medical researchers may be different than the level of carbohydrate defined by diet advisors. For the purposes of this discussion, we focus on diets that reduce (nutritive) carbohydrate intake sufficiently to dramatically reduce or eliminate insulin production in the body and to encourage ketosis (production of ketones to be used as energy in place of glucose).

Although originally low-carbohydrate diets were created based on anecdotal evidence of their effectiveness, today there is a much greater theoretical basis on which these diets rest. The key scientific principle which forms the basis for these diets is the relationship between consumption of carbohydrates and their effects on blood sugar (i.e. blood glucose) and hormone production. Blood sugar levels in the human body must be maintained in a fairly narrow range to maintain health. The two primary hormones related to regulating blood sugar levels, produced in the pancreas, are insulin, which lowers blood sugar levels, and glucagon, which raises blood sugar levels. In general, most western diets (and many others) are sufficiently high in nutritive carbohydrates that virtually every meal causes substantial insulin production and avoids ketosis, thus causing excess energy in the diet to be stored as fat (discussed in the next section). By contrast, low-carbohydrate diets, or more properly, diets that are very low in nutritive carbohydrates, discourage insulin production and tend to cause ketosis. Some researchers suggest that this causes excess dietary energy and body fat to be eliminated from the body. Although these diets remain controversial, clinical studies show that "Participants on a low-carbohydrate diet had more favorable overall outcomes at 1 year than did those on a conventional diet."

Low-carbohydrate diet advocates in general recommend reducing nutritive carbohydrates (commonly referred to as "net carbs," i.e. grams of total carbohydrates reduced by the non-nutritive carbohydrates)to very low levels. This means sharply reducing consumption of desserts, breads, pastas, potatoes, rice, and other sweet or starchy foods. Some recommend levels as low as 20-30 grams of "net carbs" per day, at least in the early stages of dieting (for comparison, a single slice of white bread typically contains 15 grams of carbohydrate, almost entirely starch). By contrast, more standard nutrition guides typically recommend consumption levels in the neighborhood of 225-325 grams of carbohydrate per day (based on a 2000 calorie a day diet).Low-carbohydrate diets often differ in the specific amount of carbohydrates allowed, whether certain types of foods are preferred, whether occasional exceptions are allowed, etc. Generally they all agree that processed sugar should be eliminated, or at the very least greatly reduced, and similarly generally discourage heavily processed grains (white bread, etc.). They vary greatly in their recommendations as to the amount of fat allowed in the diet although the most popular versions today (including Atkins) generally recommend at most a moderate fat intake.

As a related note, there is a set of diets known as low-glycemic-index diets (low-GI diets) or low-glycemic-load diets (low-GL diets), in particular the Low GI Diet by Brand-Miller et al. In reality, low-carbohydrate diets are, literally speaking, low-GL diets (and vice versa) in that they specifically limit what contributes to the glycemic load in foods. In practice, though, "low-GI"/"low-GL" diets differ from "low-carb" diets in the following ways. First, low-carbohydrate diets treat all nutritive carbohydrates as having the same effect on metabolism and generally assume that their effect is independent of other nutrients in food. Low-GI/low-GL diets base their recommendations on the actual measured metabolic (glycemic) effects of the foods eaten. Second, as a practical matter, low-GI/low-GL diets generally do not recommend diets with glycemic loads low enough to minimize insulin production and induce ketosis, whereas low-carbohydrate diets generally do.

Another related diet type, the low-insulin-index diet, is very similar except that it is based on measurements of direct insulemic responses (i.e. the amount of insulin in the bloodstream) to food rather than glycemic response (the amount of glucose in the bloodstream). Although the diet recommendations mostly involve lowering nutritive carbohydrates, there are some low-carbohydrate foods that are discouraged as well (e.g. beef).

In contrast to these diets, based on evidence for risk of heart disease and obesity, the Institute of Medicine recommends that American and Canadian adults get between 40-65% of dietary energy from carbohydrates.The Food and Agriculture Organization and World Health Organization jointly recommend that national dietary guidelines set a goal of 55-75% of total energy from carbohydrates, but only 10% should be from Free sugars (their definition of simple carbohydrates).

Ketosis and insulin synthesis: what is normal?

At the heart of the debate about most low carbohydrate diets are fundamental questions about what is a "normal" diet and how the human body is supposed to operate. These questions can be summarized as follows. Nutritive carbohydrates (starches and sugars) in the diet tend to break down very easily into glucose in the bloodstream (blood sugar) when consumed. Glucose in the blood is used by the cells in the body for energy for their basic function. Excessive amounts of glucose in the blood are toxic to the human body (the reason diabetes causes such serious health problems). In general, unless a meal is very low in starches and sugars the level of glucose will tend to rise to potentially dangerous levels. When this occurs, the pancreas automatically produces insulin to cause the liver to convert glucose into glycogen (glycogenesis) and triglycerides (which can become body fat), thus reducing the blood sugars to safe levels.Diets with a high starch/sugar content, therefore, cause sharp spikes in insulin production. As such the blood sugar levels are highly variable with every meal.

By contrast, if the diet is very low in starches and sugars (low-carbohydrate diets) the blood sugar level can fall so low that there is insufficient glucose to fuel the cells in the body. This state causes the pancreas to produce glucagon.Glucagon causes the conversion of stored glycogen to glucose and, once the glycogen stores are exhausted, causes the liver to synthesize ketones (ketosis) and glucose (gluconeogenesis) from fats and proteins, respectively. Most cells in the body can use ketones for energy instead of glucose, and since ketones are easier to produce, only a small amount of glucose is created (in other words, ketosis is the more significant process in this case). Because diets low in starches and sugars do not tend to directly affect blood sugar levels significantly, meals tend to have little direct effect on insulin levels (and so such diets tend to discourage insulin production in general).

The diets of most people in modern, so-called western nations, especially the United States contain significant amounts of starches (and, frequently, significant amounts of sugars). As such, the metabolisms of most westerners tend to operate outside of ketosis and tend to involve significant insulin production. This has been regarded by medical science in the last century as being "normal." Ketosis has generally been regarded as a dangerous (potentially life-threatening) state which unnecessarily stresses the liver and causes destruction of muscle tissues. The view that has been developed is that getting energy more from protein than carbohydrates causes liver damage and that getting energy more from fats than carbohydrates causes heart disease and other health problems. This view is still the view of the majority in the medical and nutritional science communities.

Most advocates of low-carbohydrate diets (specifically those that recommend diets similar to the Atkins Diet) argue that this metabolic state (using primarily blood glucose for energy) is not normal at all and that the human body is, in fact, supposed to function primarily in ketosis.They argue that high insulin levels can, in fact, cause many health problems, most significantly, fat storage and weight gain. They argue that the purported dangers of ketosis are unsubstantiated (some of the arguments against ketosis result from confusion between ketosis and ketoacidosis which is a related but very different process). They also argue that fat in the diet only contributes to heart disease in the presence of high insulin levels and that if the diet is instead adjusted to induce ketosis, fat and cholesterol in the diet are not a major concern (although most do not advocate unrestricted fat intake and do advocate avoiding trans fat). Further, whereas insulin in the bloodstream causes storage of food energy, when the body is in ketosis, excess ketones (which contain excess energy) are excreted in the urine and the breath.

This debate is on-going and no consensus currently exists.

Scientific research

Main article: Medical research related to low-carbohydrate diets

Because of the substantial controversy regarding low-carbohydrate diets and even disagreements in interpreting the results of specific studies it is difficult to objectively summarize the research in a way that reflects scientific consensus.Although there has been some research done throughout the twentieth century, most directly relevant scientific studies have occurred in the 1990s and early 2000s and, as such, are relatively new. Contrary to popular belief that low-carbohydrate diets damage the heart, one study found that women eating low-carbohydrate, high-fat/protein diets had the same or slightly less risk of coronary heart disease, compared to women eating high-carbohydrate, low-fat diets. Other studies have found possible benefits to individuals with diabetes, cancerand autism. The ketogenic diet, with 90% of energy from fat and much of the remaining from protein, has been used since the 1920s to treat epilepsy. The introduction of modern anticonvulsant drugs, however, substantially restricted its use. Interestingly, there has very recently been renewed interest in use of the diet, especially in children.

A study conducted in 1965 at the Oakland (California) Naval Hospital used a diet of 1000 calories per day, high in fat and limiting carbohydrates to 10 grams (40 calories) daily. Over a ten-day period, subjects on this diet lost more body fat than did a group who fasted completely. (Benoit et. al. 1965). Some subsequent studies have shown similar results. Many advocates of low-carbohydrate diets have termed this the metabolic advantage of such diets although many experts dispute whether this is truly a general phenomenon. Among others, recent studies from Stanford University (2007) and Duke University (2005) comparing various diets seem to favor low-carbohydrate diets for both weight loss and health indicators.

Criticism and controversies

Water-related weight loss

In the first week or two of a low-carbohydrate diet a great deal of the weight loss comes from eliminating water retained in the body (many doctors say that the presence of high levels of insulin in the blood causes unnecessary water retention in the body. However, this is a short-term effect and is entirely separate from the general weight loss that these diets can produce through eliminating excess body fat.

Exercise

Some critics argue that low-carbohydrate diets can inherently cause weakness or fatigue giving rise to the occasional assumption that low-carbohydrate dieting cannot involve an exercise regimen. Advocates of low-carbohydrate diets generally dispute any suggestion that such diets cause weakness or exhaustion (except in the first several days as the body adjusts) and indeed most highly recommend exercise as part of a healthy lifestyle.

Micronutrients and vitamins

The major low-carbohydrate diet guides generally recommend multi-vitamin and mineral supplements as part of the diet regimen which may lead some to believe that these diets are nutritionally deficient. The primary reason for this recommendation is that if the switch from a high-carbohydrate to a low-carbohydrate, ketogenic diet is rapid, the body can temporarily go through a period of adjustment during which the body may require extra vitamins and minerals (the reasons have to do with the body's releasing excess fluids that were stored during high-carbohydrate eating). In other words, the body goes through a temporary "shock" if the diet is changed to low-carbohydrate dieting quickly just as it would changing to a high-carbohydrate diet quickly. This does not, in and of itself, indicate that either type of diet is nutritionally deficient. Some critics have argued or implied that "carbohydrates contain vitamins" and mineralsbut this suggestion is strictly false (by definition). While it is true that many foods that are rich in carbohydrates are also rich in vitamins and minerals, there are many low-carbohydrate foods that are similarly rich in vitamins and minerals.Also, the important vitamin B12 is only available in significant quantities from animal sources and not from vegetable sources.

It should be noted that, contrary to the recommendations of most diet guides, some individuals may choose to avoid vegetables altogether in order to minimize carbohydrates. It is more likely that such a diet could be nutritionally deficient (some would dispute this based on cases like Vilhjalmur Stefansson).

Other controversies

In 2004, the Canadian government ruled that foods sold in Canada could not be marketed with reduced or eliminated carbohydrate content as a selling point because reduced carbohydrate content was not determined to be a health benefit, and that existing "low carb" and "no carb" packaging would have to be phased out by 2006.

Some variants of low carbohydrate diets involve substantially lowered intake of dietary fiber which can result in constipation if not supplemented. For example, this has been a criticism of the Induction stage of the Atkins diet (note that today the Atkins diet is more clear about recommending a fiber supplement during Induction). Most advocates today argue that fiber is a "good" carbohydrate and in fact encourage a high-fiber diet.

It has been hypothesized that a diet related change in blood acidity can lead to bone loss through a process called ketoacidosis, as mentioned earlier in this article. However ketoacidosis, which is often confused with ketosis, is an acute medical condition caused by extreme fasting or as a symptom of untreated diabetes, and is not likely to be induced by a proper low-carbohydrate diet.

One of the occasional side effects of a ketogenic diet is a noticeable smell of ketones in the urine, perspiration, and breath. This is caused by the temporary metabolism of fatty-acid derived acetyl-coa into the ketone form, so that it may be released from the liver into the blood stream. The ketones are then re-assembled when they reach various body tissues to form acetyl-coa again, which is used as the precursor to energy.

Diet soda

From Wikipedia, the free encyclopedia

Diet sodas (also diet pop, diet, sugar-free, or light soft drinks, refreshments, or carbonated beverages) are sugar-free, artificially sweetened, non-alcoholic carbonated beverages generally marketed towards health-conscious people, diabetics, athletes, and other people who want to lose weight or stay fit.

Sweetening

Different artificial sweeteners are used instead of sugar to give diet soda a sweet taste and some are often used simultaneously. Opinion is mixed as to the taste of these beverages: some think they lack the taste of their sugar-sweetened counterparts, others think the taste is similar. Some also note an unusual non-sugary aftertaste. Some feel the opposite—that diet soda has no aftertaste and that soda sweetened by high fructose corn syrup has a gritty, over-sweet aftertaste.

Aspartame

Aspartame, commonly known by the brand name NutraSweet, is one of the most commonly used artificial sweeteners. It had the great commercial advantage of not being linked in the public mind with cancer, and by the mid-1980s, American manufacturers were switching en masse from saccharin to aspartame. The 1982 introduction of aspartame-sweetened Diet Coke accelerated this trend. Today, at least in the United States, "diet" is nearly synonymous with the use of aspartame in beverages.

Cyclamates

The first artificial sweeteners used in diet soda were cyclamates (often synergistically with saccharin). While many say these cyclamate-sweetened soda had a more pleasant taste than the diet soda that followed them, in 1970 the Food and Drug Administration banned cyclamates in the United States on evidence that they caused cancer in lab rats. Cyclamates are still used in many countries around the world, including for diet soda.

Saccharin

Once cyclamates were banned, American producers turned to saccharin. Saccharin alone was often criticized for having a bitter taste and "chemical" aftertaste. Some manufacturers, such as Coca-Cola with Tab, attempted to rectify this by adding a small amount of sugar. In 1977, the FDA was petitioned to ban saccharin, too, as a carcinogen, but a moratorium was placed on the ban until studies were conducted. The ban was lifted in 1991, but by that time, virtually all diet soda production had shifted to using aspartame. Perhaps the most notable holdout is Tab, which nevertheless also uses some aspartame in its formula.

Sucralose and acesulfame potassium; "sugar-free" sodas

Recently two other sweeteners, sucralose (marketed as Splenda) and Acesulfame potassium ("Sunett" or "Ace K", which is usually used in conjunction with aspartame, sucralose, or saccharin rather than alone) have come into growing use, particularly by smaller beverage producers (e.g. Big Red). Diet Rite is the non-aspartame diet soda brand with the highest sales today; it uses a combination of sucralose and acesulfame potassium.

Advocates say drinks employing these sweeteners have a more natural sugar-like taste than those made just with aspartame and do not have a strong aftertaste. The newer aspartame-free drinks can also be safely consumed by phenylketonurics, because they do not contain phenylalanine. Critics say the taste is not better, merely different, or note that the long-term health risks of all or certain artificial sweeteners is unclear.

The widespread, though not universal, agreement that the newest formulations taste much more "normal" and sugar-like than the older diet sodas have prompted some producers, such as Jones Soda, to abandon the "diet" label entirely in favor of "sugar-free soda," implying that the taste is good enough to drink the soda even when not trying to lose weight. (This idea was first floated by Diet Coke in 1984, with the tagline, "Just For the Taste of It.")

In 2005, the Coca-Cola Company announced it would produce a new formulation of Diet Coke sweetened with sucralose, to be called Diet Coke with Splenda, but it would continue to produce the aspartame version as well. There were also rumors that a sugar-free version of Coca-Cola Classic, also sweetened with sucralose, was being formulated as well. This formulation was eventually called Coca-Cola Zero, though it is sweetened with aspartame.

History

The beginning of the diet soda or refreshment era was in 1952, when Kirsch Bottling in Brooklyn, New York launched a sugar free ginger ale called No-Cal. It was designed for diabetics, not dieters, and distribution remained local. Royal Crown Cola placed an announcement in an Atlanta newspaper in 1958 announcing a diet soda product, Diet Rite. In 1963, the Coca-Cola Company joined the diet soda market with Tab, which proved to be a huge success. Tab was originally sweetened with cyclamates and saccharin.

Tab, Diet Rite, and Fresca (a grapefruit-flavored soda introduced by Coca-Cola) were about the only well-known diet refreshment on the markets until Pepsi released Diet Pepsi in the 1960s (initially as Patio Diet Cola). Coca-Cola countered by releasing Diet Coke in 1982. After the release of Diet Coke, Tab took a backseat at the Coca-Cola production lines; Diet Coke could be more easily identified by consumers as associated with Coca-Cola than Tab. Also, a study was released revealing that saccharin was a possible carcinogen, leading to Coca-Cola's decision of pushing Tab's production numbers down. During the middle 1980s also, the alcohol industry began to follow lead to the refreshment industry, with some beer companies putting sugar-free beer on the market.

By the start of the 1990s, a wide array of different companies had their own diet refreshments on supermarket shelves. Tab made a comeback during the late 1990s, after new studies demonstrated that saccharin is not an important factor in the risk of cancer. Nevertheless, the Coca-Cola Company has maintained its 1984 reformulation, replacing some of the saccharin in Tab with NutraSweet.

By 2002, some soda companies had diversified to include such flavors as vanilla and lemon among their products, and diet sodas were soon begun to be produced with those flavors too (see Diet Vanilla Coke, Diet Pepsi Vanilla). By 2004, several alcohol companies had begun to release sugar-free or "diet" alcoholic products too.

Health concerns

Along with possible health concerns of sugar substitutes and caffeine overuse, the effectiveness of diet soda as a weight loss tool should also be considered.

Changing the food energy intake from one food will not necessarily change a person's overall food energy intake, or cause a person to lose weight. One study, at the University of Texas Health Science Center at San Antonio, reported by Sharon Fowler at the ADA annual meeting, actually suggested the opposite, where consumption of diet soda was correlated with weight gain. While Fowler did suggest that the undelivered expected calories from diet soda may stimulate the appetite, the correlation does not prove that consumption of diet soda caused the weight gain. The weight gain may have caused the consumption of diet soda. The ADA has yet to issue an updated policy concerning diet soda, and may face a conflict of interest in doing so, as they are now in partnership with candy and soda companies.

An independent study by researchers with the Framingham Heart Study in Massachusetts, has turned up results which indicate that the consumption of diet soda correlates with increased metabolic syndrome. Of the 9,000 males and females studied, findings stated that 48% of the subjects were at higher risk for weight gain and elevated blood sugar. The researchers also acknowledged that diet soda drinkers were less likely to consume healthy foods, and that drinking diet soda flavored with artificial sweeteners more than likely increases cravings for sugar flavored sweets.

Individuals who drink excessive amounts of regular soda may experience weight loss if they switch to diet soda.

Nomenclature

For cultural reasons, in some countries outside the United States and Canada, the term "light" is often used instead of "diet". The word diet in these countries typically refers to the programs given by doctors to patients who need to lose weight, and not as a way to describe food products.

Reduced-calorie soda

In an effort to cash in on the surging popularity of low-carbohydrate diets, in 2004 both Coca-Cola and Pepsico released reduced-calorie versions of their flagship sodas that contain approximately half the sugar of the regular version. The Pepsi variant, Pepsi Edge, is sweetened with sucralose and corn syrup. The sweetening of the Coca-Cola variant, Coca-Cola C2, is a combination of corn syrup, aspartame, acesulfame potassium, and sucralose. In May of 2005, Pepsi announced that they will abandon the market by the end of the year, citing lackluster sales. It is rumored that Coke is soon to follow suit.

Half the sugar of a can of regular cola is still more sugar than many people on popular low-carbohydrate diets are permitted to have in a day. It is possible that these sodas are targeted, instead, at so-called "carb-conscious consumers" who are paying attention to, but not trying to drastically reduce, their carbohydrate intake.

Incomplete list of major diet soda brands or brands with diet versions, with sweetener(s)

Product	Aspartame	Sucralose	Acesulfame potassium	Saccharin	Xylitol	Stevia
7 Up Plus (multiple flavors)		Y	Y
AriZona Diet Green Tea		Y
Blenheim's Diet Ginger Ale	Y
Boylan's Diet (multiple flavors)		Y	Y
Coca-Cola C2 (contains corn syrup)	Y	Y	Y
Coca-Cola Zero	Y		Y
Cricket Diet Cola		Y
Crystal Light (bottles)		Y
Diet 7 Up	Y		Y
Diet A&W Root Beer	Y
Diet Barq's Root Beer	Y
Diet Big Red	Y		Y
Diet Black Cherry Vanilla Coke	Y		Y
Diet Canada Dry	Y
Diet Cherry Coke	Y		Y
Diet Cherry Vanilla Dr Pepper	Y
Diet Coke	Y
Diet Coke with Lemon	Y		Y
Diet Coke with Lime	Y		Y
Diet Coke with Splenda		Y	Y
Diet Dr Pepper	Y
Diet Dr Pepper Berries & Cream	Y		Y
Diet Kist	UNKNOWN	UNKNOWN	UNKNOWN	UNKNOWN
Diet Kola Champagne (Puerto Rican soda)	UNKNOWN	UNKNOWN	UNKNOWN	UNKNOWN
Diet Materva (with mate)	UNKNOWN	UNKNOWN	UNKNOWN	UNKNOWN
Diet Mountain Dew	Y	Y	Y
Diet Mug Root Beer	Y
Diet Orange Crush (available in Canada)		Y
Diet Orange Tropicana Twister Soda	Y		Y
Diet Pepsi	Y
Diet Pepsi Jazz (multiple flavors)	Y		Y
Diet Pepsi Lime	Y		Y
Diet Pepsi Vanilla	Y		Y
Diet RC Cola		Y
Diet Red Bull	Y		Y
Diet Rite (multiple flavors)		Y	Y
Diet Rockstar		Y	Y
Diet Safeway Select	UNKNOWN	UNKNOWN	UNKNOWN	UNKNOWN
Diet Schweppes Ginger Ale	Y
Diet Slice (orange flavor)	UNKNOWN	UNKNOWN	UNKNOWN	UNKNOWN
Diet Sprite Zero	Y		Y
Diet Sunkist	Y		Y
Diet Vanilla Coke	Y		Y
Diet Wild Cherry Pepsi	Y		Y
Dr. Brown's Diet (multiple flavors)	Y
Fresca (multiple flavors)	Y		Y
Hansen's Natural Soda		Y	Y
Pepsi ONE		Y	Y
Sierra Mist Free	Y		Y
Slice ONE (multiple flavors)		Y	Y
Soda Club (multiple flavors)		Y	Some
Stewart's Diet Root Beer	Y
Sugar Free Full Throttle		Y	Y	Y
Sugar Free Full Throttle Fury		Y	Y	Y
Sugar Free Jones Soda		Y
Sugar Free Mountain Dew MDX	Y	Y	Y
Tab	Y			Y
Vault Zero	Y		Y
Virgil's Diet (multiple flavors)					Y	Y