Nutrition Fundamentals

The Benefits of a Plant-Based Diet

Saturday, April 10, 2010

Nutrient Fundamentals II

In the lecture Nutrient Fundamentals II, Dr. Campbell proposes that there are no nutrients in animal-based foods that are not better obtained by plant-based foods. Explain to an interested acquaintance how science supports this premise. Include specific examples from the lecture.

First, some clarification is in order. By “better”, I understand Dr. Campbell to be referring to the bio-availability and metabolism of these nutrients from the original foodstuffs, so we bypass the arguments about availability of the foods themselves, as with inhabitants of the Arctic who survive largely on fish and sea mammals, or the poor who live in lands with little or no access to vegetation. I will further bypass those with other constraints, such as pregnant or lactating women, infants (who should be feeding on their mothers’ milk—an animal product—and who are then, strictly speaking, not living on only a plant-based diet), the aged, or those who require special diets as a result of disease or severe allergies, because dealing with biological variability and dose-response would be dilutive to the question. Additionally, I will not address the modifications to, or contamination of, these nutrients through food additives or colorings, pesticides, PCBs, dioxins, organochlorines, polybrominated diphenyl ethers, trioxypurine, adrenalin, prions, fecal matter, colon bacteria, toxoplasmosis, trichinosis, hormones, antibiotics, polychlorinated biphenols, toxic metals, GMOs, antibiotics, processing, packaging, refrigeration, storage or cooking. Furthermore, I’ll steer clear of the meaning of “better” in relation to moral arguments regarding our use of nonhuman animals for food, as well as other negative externalities flowing from a meat-based diet, including but not limited to the following:

- land and water usage;

- land and water pollution;

- air pollution;

- energy consumption;

- global climate change;

- the rise of human resistance to common antibiotics;

- world hunger through the inefficient conversion efficiency in turning plant food into nonhuman animal food, then into human animal food;

- world peace (which “…begins when the hungry are fed”);

- the development and spreading of infectious diseases (e.g., Pathogenic Escherichia coli, Camplyobacter, Salmonella, Swine Flu, Bovine Spongiform Encephalopathy (BSE) , Avian Flu, and the Nipah Virus) from highly confined, genetically similar animals kept in unsanitary and stressful conditions;

- the rise of antibiotic-resistant “superbugs”;

- occupational hazards of the slaughterhouse industry;

- loss of biodiversity;

- human health care, environmental or veterinary costs as a result of a meat-centric diet, or

- the price-distorting consumption of governmental subsidies and the corresponding rise of self-serving corporate interests tied to those subsidies.

Finally, I assume that Dr. Campbell’s statement was in reference to humans, while noting that that does not rule out the possibility that a plant-based diet is also best for nonhuman omnivores (e.g., domesticated dogs, wolves, etc.), or carnivores (e.g., domesticated cats) who consume supplemental nutrients (e.g., taurine) which are, for them, essential.

Dr. Campbell’s premise can be scientifically supported through several approaches:

1. By comparing and contrasting the availability and metabolization of nutrients from plant-based and animal-based sources;

2. By reviewing epidemiological studies to understand the effects of diet on humans, and, where these studies demonstrate only associations but do not infer causality, by reviewing controlled clinical trials to understand possible causal roles, and

3. By comparing the anatomy and physiology of humans with that of herbivores, omnivores and carnivores.

First, some definitions:

A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment.

Organic nutrients include carbohydrates, lipids (fats, oils and fatty acids), alcohols, proteins (or their building blocks, amino acids), and vitamins. Inorganic nutrients include chemical compounds such as dietary minerals, water, electrolytes (mineral-based compounds), and oxygen (the latter two are “essential”, but are not generally considered “food” when taken in isolation).

Essential nutrients are those chemicals or chemical compounds required for normal body functioning that either cannot be made by the body or which cannot be made in amounts adequate for good health. Of the nutrients mentioned above, only certain fatty acids, amino acids, vitamins, minerals and electrolytes are essential nutrients.

1. Comparing and Contrasting the Availability and Metabolization of Nutrients From Plant-Based and Animal-Based Sources

All of the essential organic nutrients for humans are made by plants, but not all can be made by animals, and humans have not fully adapted to eat animal-based foods. While plants do not make the essential inorganic nutrients, they do absorb them from the soil through their roots, where they are available for consumption. One caveat: There are no reliable, unfortified plant sources of vitamin B-12, so fortified foods or supplements may be necessary for the optimal health those who consume only plant-based foods. But B-12 is required in smaller amounts than any other known vitamin, and a body that has accumulated an excess of B-12 can take more than a year to use up its supply.

Plants are primarily responsible for protecting against cancers, heart disease, diabetes, obesity, and other sort of ailments associated with aging. Whereas an animal-based diet generally provides an excessive intake of protein, fat and “bad carbohydrates” (like sugar and refined flour), a whole food, plant-based diet increases the consumption of vitamins, antioxidants and complex carbohydrates (e.g., fiber). Protein in animal-based foods are better able to foster the development of cancer and catalyze the formation of cholesterol, which leads to the formation of atherosclerosis in the blood vessels. Diets that avoid animal-based foods tend to have lower levels of saturated fat, cholesterol and animal protein, and higher levels of carbohydrates, fiber, antioxidants, phytochemicals and essential vitamins and minerals. Saturated fatty acids are mostly found in animal-based foods, with rare exceptions (as with coconut oil). Polyunsaturated fats or unsaturated fats, in general, are found in plants. Fruits and vegetables contain antioxidant substances, such as vitamin C, vitamin E, and carotenoids, which protect cells against oxidative damage, which is related to cancer risk and other health problems. Phytochemicals, manufactured by plants, include cartenoids, thiocyonates, daidzein and genistein, and dietary fiber, and vitamins. These help prevent the formation of carcinogens, reduce cholesterol levels, help move food through the intestinal tract, and help keep cells healthy.

2. A Review of Epidemiological Studies of Plant-Based v. Animal-Based Diets

At least six large-scale epidemiological studies have considered the health of plant-based diets to animal-based diets:

I. Dr. Phillips studied 25,000 Seventh Day Adventist (SDA) California residents over a six-year period. Dr. Phillips compared those SDAs who strictly followed the vegetarian lifestyle with “normal” meat-eating Californians, and found that vegetarian men SDAs were about ten times less likely to contract coronary heart disease than a “normal” meat-eating person. Further, Dr. Phillips’ project continued to study these individuals for 20 years, after which he offered scientific proof that the more meat you eat, the more at risk you are of contracting coronary heart disease, and that the relative risk of fatal heart disease closely correlates with the frequency of eating meat.

II. In 1985 scientists for the (Japanese) National Cancer Center Research Institute followed 122,261 men over 16 years, and found that by simply adding one factor—meat—to an otherwise healthy lifestyle, men increased their risk of dying from heart disease by 30%.

III. In 1988, after studying 1,904 people for five years, German researchers found that deaths from all causes among vegetarians were only 37% of that of the average meat-eating population. The vegetarians also experienced only 56% of the “normal” cancer rate, and heart disease was 20% of the “normal” rate (it was 40% of the “normal” rate once smoking was taken into account).

IV. British researchers tracked the causes of death of 4,671 British vegetarians over seven years, and found that for male vegetarians, the death rate from all causes was 50% that of the general population, and for females, 55%. For heart disease alone, male vegetarians experienced 44% of the “normal” death rate, and female vegetarians had 41% the “normal” death rate. The researchers also compared vegetarians to a similar population who shopped at health food shops and found vegetarians to have only 60% of that average population for dying of heart disease.

V. T. Colin Campbell’s “China Study” discusses the most comprehensive large study ever performed on the relationship between diet and the risk of developing disease. Campbell performed the study in China because the US population is too homogenous, and the differences in diet and disease are relatively large in various parts of China. This study is the largest epidemiological study of its kind, with a "survey of death rates for twelve different kinds of cancer for more than 2,400 counties and 880 million (96%) of their citizens" conducted jointly by Cornell University, Oxford University, and the Chinese Academy of Preventive Medicine over the course of twenty years." The authors correlated animal-based diets with disease. Key findings include:

· 70% of the protein in the average Western diet comes from animals, while in China, only 7% does.

· Most Chinese suffer very little from the major chronic diseases of the West, although the affluent Chinese who do consume similar amounts of animal protein to Westerners also have the highest rates of heart disease, cancer, and diabetes.

· The Chinese consume 20% more calories than Westerners, but Westerners are 25% fatter than the Chinese due to Westerners’ higher consumption of fats and lower consumption of complex carbohydrates (i.e., plants).

· The average Chinese adult shows no evidence of iron-deficiency anemia, and consumes almost twice the iron of an average American, but the vast majority of it is plant-based.

· The scientists behind the study predict that the majority of Western diseases such as cancers, cardiovascular diseases, and diabetes could be prevented until we were about age 90 if we were prepared to become vegetarians.

· The risk of developing Type I diabetes is strongly correlated with the consumption of cow's milk by infants.

· Autoimmune diseases such as Type I diabetes, multiple sclerosis and rheumatoid arthritis have certain common features and may share the same cause or causes. Autoimmune diseases are more prevalent among people who live at higher geographic latitudes, and also among people who consume a diet high in animal protein, particularly cow's milk.

· Cognitive impairment and dementia including Alzheimer's disease are linked to hypertension, high blood cholesterol and damage caused by free radicals, and that these risk factors can be controlled by diet.

· Breast cancer is linked to the long-term exposure to higher concentrations of female hormones, which in turn is associated with early menarche - age at first menstruation, late menopause and a high concentration of blood cholesterol, and that all of these risk factors are linked to growth and a diet high in animal protein. The average Chinese woman is exposed to about 35% to 40% of the lifetime estrogen exposure of the average British or American woman, and that the rate of breast cancer among Chinese women is about one-fifth of the rate among western women.

· Lower rates of colorectal cancer are associated with the consumption of plants high in fiber such as beans, leafy vegetables and whole grains.

· The authors described a diet study conducted by James D. Anderson, M.D., of 50 patients - 25 with Type I diabetes and 25 with Type II diabetes, who were taking medication in the form of insulin injections to control their blood glucose concentrations. The authors reported that after these patients switched from the American-style diet recommended by the American Diabetes Association to a high-fiber, low-fat, plant-based diet, the patients with Type I diabetes were able to reduce their medication by an average of 40% within 3 weeks of changing their diet and 24 of the 25 patients with Type II diabetes were able to stop taking their medication within weeks of changing their diet.

· Diet studies show that a diet that includes carotenoids, which are found in colorful vegetables, provide protection from macular degeneration, an eye disease that can cause blindness, and that a diet that includes lutein, a particular antioxidant found in spinach, provides protection from cataracts. The authors state that cholesterol, saturated fats and animal protein are three nutrients that characterize animal-based foods, and they ask, "...isn't it perfectly reasonable to wonder whether animal-based food, and not just these three isolated nutrients, causes heart disease?"

· Eating plant protein has a greater power to lower cholesterol levels than reducing fat or cholesterol intake. They add that "Western" diseases were relatively rare in China by western standards adding for example that "at the time of our study, the death rate from coronary heart disease was seventeen times higher among American men than rural Chinese men."

· The consumption of animal protein is linked to risk factors for the formation of kidney stones. They state that increased levels of Calcium and Oxalate in the blood may result in kidney stones, and that recent research shows that kidney stone formation may be initiated by free radicals.

· "Diet can cause small shifts in calorie metabolism that lead to big shifts in body weight" adding that "the same low-animal protein, low-fat diet that helps prevent obesity also allows people to reach their full growth potential."

· Most Chinese consume no dairy products, yet osteoporosis is uncommon in China, despite an average life expectancy of seventy years. According to Campbell, “Osteoporosis tends to occur in countries where calcium intake is highest and most of it comes from protein-rich dairy products”. Osteoporosis is linked to the consumption of animal protein because animal protein, unlike plant protein, increases the acidity of blood and tissues. They add that to neutralizeacid, Calcium, a very effective base, is pulled from the bones, which weakens them and puts them at greater risk for fracture. The authors add that "in our rural China Study, where the animal to plant ratio [for protein] was about 10%, the fracture rate is only one-fifth that of the U.S."

VI. "Meat Intake and Mortality: A Prospective Study of Over Half a Million People", pub. March 23, 2009 by the AMA in its Archives of Internal Medicine, was authored by a team of epidemiologists at the National Cancer Institute. Key findings include:

· Heart Disease/CVD: Over 10 years, eating the equivalent of a quarter-pound hamburger (red meat) daily gave men in the study a 22 percent higher risk of dying of cancer and a 27 percent higher risk of dying of heart disease. That's compared to those who ate the least red meat, just 5 ounces per week. Similarly, the risk of dying from cardiovascular disease was higher by 27 percent for men and 50 percent for women; for processed red meat, the risk was 9 percent higher for men and 38 percent higher for women.

· All Causes of Death: Men and women eating the highest amount of red meat were found to have a 31 percent and 36 percent, respectively, higher risk of dying from any cause than those eating the least amount. Women eating the most processed meat were 25 percent more likely to die early than those eating the least of this type of meat, while men had a 16 percent increased risk, the study found.

· Cancer: Dying from cancer also was more likely among those eating the most red meat: 22 percent higher for men, 20 percent for women. The risk for death from cancer increased 12 percent for men and 11 percent for women who ate the greatest amount of processed meat.

· Mixed results on "white meat"... When comparing the highest with the lowest quintile of white meat intake, there was an inverse association for total mortality and cancer mortality, as well as all other deaths for both men and women. In contrast, there was a small increase in risk for CVD mortality in men with higher intake of white meat. The authors also noted a 24 percent higher risk of dying from heart problems among men who had never smoked and who ate more white meat. Women faced a 20 percent higher risk.

3. Comparative Anatomy and Physiology of Humans, Carnivores, Omnivores and Herbivores

One way to explore the optimal diet is through morphology (anatomical form). Although many modern humans are behavioral omnivores (i.e., they eat as omnivores, with diets consisting of a wide variety of plant and animal foods), we are anatomically and physiologically adapted to be herbivorous (plant eaters). Biologists have established that animals who share physical characteristics also share a common diet. The following chart, adapted from Dr. Mills’ publication The Comparative Anatomy of Eating, shows that humans share the anatomy of herbivores, rather than that of omnivores or carnivores:

The Comparative Anatomy of Eating, by Milton R. Mills, M.D.





Facial Muscles

Reduced to allow wide mouth gape




Jaw Type

Angle not expanded

Angle not expanded

Expanded angle

Expanded angle

Jaw Joint Location

On same plane as molar teeth

On same plane as molar teeth

Above the plane of the molars

Above the plane of the molars

Jaw Motion

Shearing; minimal side-to-side motion

Shearing; minimal side-to-side

No shear; good side-to-side, front-to-back

No shear; good side-to-side, front-to-back

Major Jaw Muscles



Masseter and pterygoids

Masseter and pterygoids

Mouth Opening vs. Head Size





Teeth (Incisors)

Short and pointed

Short and pointed

Broad, flattened and spade shaped

Broad, flattened and spade shaped

Teeth (Canines)

Long, sharp and curved

Long, sharp and curved

Dull and short or long (for defense), or none

Short and blunted

Teeth (Molars)

Sharp, jagged and blade shaped

Sharp blades and/or flattened

Flattened with cusps vs complex surface

Flattened with nodular cusps


None; swallows food whole

Swallows food whole and/or simple crushing

Extensive chewing necessary

Extensive chewing necessary


No digestive enzymes

No digestive enzymes

Carbohydrate digesting enzymes

Carbohydrate digesting enzymes

Stomach Type



Simple or multiple chambers


Stomach Acidity

Less than or equal to pH 1 with food in stomach

Less than or equal to pH 1 with food in stomach

pH 4 to 5 with food in stomach

pH 4 to 5 with food in stomach

Stomach Capacity

60% to 70% of total volume of digestive tract

60% to 70% of total volume of digestive tract

Less than 30% of total volume of digestive tract

21% to 27% of total volume of digestive tract

Length of Small Intestine

3 to 6 times body length

4 to 6 times body length

10 to more than 12 times body length

10 to 11 times body length


Simple, short and smooth

Simple, short and smooth

Long, complex; may be sacculated

Long, sacculated


Can detoxify vitamin A

Can detoxify vitamin A

Cannot detoxify vitamin A

Cannot detoxify vitamin A


Extremely concentrated urine

Extremely concentrated urine

Moderately concentrated urine

Moderately concentrated urine


Sharp claws

Sharp claws

Flattened nails or blunt hooves

Flattened nails

Consider how eating a 'plant-based diet' differs from 'being vegan'.

A plant-based diet consists of a food regimen that consists of only foods that are part of the vegetable kingdom. Followers of plant-based diets generally seek the health benefits of such foods.

Veganism is a philosophy and lifestyle that seeks to exclude the use of animal products of any kind for food, clothing, or any other purpose. In addition, many vegans strive not to use or consume products that indirectly harm animals of any kind. For example, many vegans will choose not to consume palm oil, a vegetable oil, the demand for which has led to extensive habitat destruction of orangutans and may cause the extinction of the species in Sumatra and Borneo.

Ethical Veganism, as opposed to veganism, sets forth beliefs that justify the practice.

While many people associate veganism with “animal rights”, the Vegetarian Resource Group's Vegetarian Journal 1998 reader survey indicated that 82% of readers were interested in vegetarianism because of health, versus 75% because of ethics, concern for the environment, or animal rights.

Vegan diets are a form of vegetarianism, but because vegetarianism deals exclusively with food, the concept of a "vegetarian lifestyle" is meaningless. The only thing a vegetarian has in common with other vegetarians is what they don't eat, and that list of exclusions tends to dilute the concept of vegetarianism. Examples of “vegetarian” variations and so-called “vegetarian want-to-bes” are:

- Lacto-vegetarianism – This includes dairy products but excludes eggs.

- Ovo vegetarianism (or eggetarianism) – This diet includes eggs but not meat or dairy products.

- Lacto-ovo-vegetarianism includes dairy and egg products but excludes beef, pork, poultry, fish, shellfish or animal flesh of any kind.

- Semi-vegetarianism – Used to describe the practice of excluding some meat (particularly red meat) from the diet while still consuming limited amounts of poultry, fish, and/or seafood.

- Pescetarianism – This diet includes fish or invertebrate seafood, but not mammals or birds.

- Flexitarianism – This is a semi-vegetarian diet involving the practice of eating mainly vegetarian food, but making occasional exceptions for social, pragmatic, cultural, or nutritional reasons.

- Pollotarianism – This is a semi-vegetarian diet that includes poultry, dairy and eggs, but excludes meat from fish or mammals.

- Raw veganism (or perhaps, more properly, raw “extreme vegetarianism”) – This is a diet which combines a plant-based diet and raw foodism. It excludes all food of animal origin, and all food cooked above 48 degrees Celsius (118 degrees Fahrenheit), although the latter limit is sometimes relaxed to “at least 75% raw foods”.

- Fruitarianism – This is a subset of “raw veganism” and excludes all but the eating of ripe fruits of plants and trees.

- Sproutarianism – This is a subset of “raw veganism” and refers to a diet consisting mainly of sprouted seeds.

- Juicearianism – This is a subset of “raw veganism” and refers to a diet which consists mostly of the juice from fresh fruit and vegetables.

- Raw foodism (or rawism) – This diet relies on un-cooked, un-processed, and often organic, plant-based foods as a large percentage of the diet. Some raw foodists follow some variation of a raw vegetarianism or raw plant-based diet, while others follow a raw omnivorous diet and still others follow a diet of only raw animal-based foods.

- Macrobiotic – This diet advocates eating grains as a staple food supplemented with other foodstuffs such as vegetables and beans (and, often, seafood), and avoiding the use of highly processed or refined foods, "nightshade vegetables" (potato, pepper and eggplant), refined sugar and tropical fruits.

Source: The Vegetarian Resource Group (see: )