We are badly in need of a study that compares good vegetarian to good meat-containing diets using quality foods, with high vegetable content and good quality fats in both diets. Too often vegetarians are compared to a standard American population, health-conscious vegans are compared to non-health conscious omnivores and studies on omnivores with low meat diets are extrapolated to suggest that a diet with no animal food altogether may be superior. The study should isolate the effects of gluten from other starchy foods and meats from fish.There was a study in the 1970s that supposed a loss of bone (measured by urinary calcium excretion) with a diet high in meat. The study lasted two weeks and subsequent studies showed that no loss occurred after two weeks, so that the effect might be transitional. But urinary calcium excretion may not come at the cost of bone. Additional studies by Kerstetter and Insogna demonstrated that there is higher absorption in the intestine and net calcium increases with high protein in the elderly. Kerstetter also demonstrated using tracers that the calcium in the urine from bone goes -down- while calcium from absorption goes up.
In fact other studies indicate that the phytates in legumes, traditionally consumed by vegetarians or vegans can lock up minerals necessary for bones. Fermentation, and to a lesser extent, cooking can reduce the anti-nutrient effect of legumes, and isoflavones in the beans may help counteract the phytic acid.
Grain based vegetarian diets contribute to hyperinsulinemia (high blood insulin) which causes the excretion of magnesium and calcium in the urine and can increase osteoporosis. This applies to omnivores who have high carbohydrate content as well. Fat taken with carbohydrates helps minimize the effects of insulin spikes, and meat eaters do tend to have more dietary fat. So while some vegetarians may be at risk from low fat/high grain diets it is not exclusive to vegetarians
This seems contradicted by the results of a 1972 study that matched 25 lacto-ovo vegetarians with omnivores of the same age and gender showed lower bone density in the omnivores. However:
- Finger bone density determinations through absorptiometry or X-ray are highly subject to error
- The study was not double blind, increasing the subjectivity of measurement
- While the subjects were matched for age and gender, they were not matched for body composition, smoking, sugar, coffee and alcohol consumption or for health consciousness
- British lacto-ovo vegetarians tend to have high dairy calcium and to have good health habits
- The sample size was quite small
A 1974 study found that Inuit had lower bone density than similar Caucasians and attributed it to their meat rich diet. However Weston Price had earlier found people such as the Massai and the Inuit who subsist primarily on meat to have healthier teeth and dental arches than groups subsisting primarily on vegetable foods. And skeletal studies of pre-Columbian Native Americans found height, bone density and dental health higher in people with traditionally high meat diets. Diets had changed by 1974, so the issue might well have been the introduction of sugars and other modern foods.
In 1986 Dr. Herta Spencer noted that the major animal and human studies that correlated calcium loss with high protein diets used isolated, fractionated amino acids from milk or eggs which lacked fat soluble vitamins and also have crosslinked dehydrated proteins.
- Vitamin D, which was missing, is necessary to assimilate calcium in bones
- Oil soluble vitamins A, D, K and E are also important to bone formation
- Her 1983 studies had shown that when protein is given as meat, subjects do not show any increase in calcium excreted, or any significant change in serum calcium, even over a long period.
A low carbohydrate diet is often conflated with a high meat diet, although one can be a low carbohydrate vegetarian. A grain-based diet is often conflated with a vegetarian diet although vegetarians can have a tuber and root based diet.
A recent study in the New England Journal of Medicine compared diets with different amounts of fats, protein or carbohydrates and concluded that none was different in weight loss over 2 years. This has been used to target Atkins-type carnivorous diets since it is easier to have a low carbohydrate diet with meats. However closer attention to the data showed:
- There was no low carbohydrate diet. The purported low carb diet had 135 grams of carbohydrates, more than twice the amount usually recommended for low carbohydrate, high protein diets.
- Nevertheless, the lowest carbohydrate diet showed superior blood lipids despite higher fats and probably more animal fats
- The quality of the foods was not regulated- there were breads, industrially processed meat which has different fat profiles, low nutrient density foods. Only macronutrients differed.
- While people with the higher fat tended to eat more meat, there were no strictly vegetarian controls. Thus the study tells us nothing about the value of a vegetarian diet versus an omnivorous diet.
What of diets that were more explicitly testing vegetarians against omnivores? A 1994 study in the British Medical Journal purported to show that vegetarians had 40% less cancer, heart disease and lower mortality however:
- Vegetarians were drawn from the Vegetarian Society and society members chose the meat eaters, so selection was not random
- More of those in the vegetarian group were females, who live longer
- More of the omnivores were male, and in the age range where heart disease is more prevalent
- The average age of the vegetarian group was younger
- The diets were quite different, aside from absence of meat so the information would not show benefits from the absence of meat
A famous 1984 study of Seventh Day Adventists, who do not eat meat, showed that they had lower cancer and heart disease rates than the population at large.
- The population at large included people not interested in health, with poor exercise habits, junk food, little spiritual focus and loose social cohesion. The Seventh Day Adventist group did not.
- The authors of the study concluded that the results did not justify vegetarianism saying ‘ We hope that no-one will take data from this report and use it to say “Food A lowers or food B raises mortality risk”.’
- Mormons in Utah who eat considerable quantities of meat have similar low mortality, cancer and heart attack rates. Both groups are close knit, interested in health, and have a strong spiritual bent.
A study by Neal Bernard, involving 99 people with Type 2 diabetes found that they did three times better in controlling blood sugar on a low fat vegan diet than the American Diabetes Diet which includes meat.
- The American Diabetes diet has high levels of carbohydrates, around 135 grams, and too low levels of vegetables
- The vegan diet was essentially lowfat Atkins without meat and dairy. It allowed a half cup of grain a day and depended on low glycemic vegetables and fruit. This was fewer carbohydrates than the ADA diet.
- The conclusion of the study says: “Both diets were associated with sustained reductions in weight and plasma lipid concentrations. In an analysis controlling for medication changes, a low-fat vegan diet appeared to improve glycemia and plasma lipids more than did conventional diabetes diet recommendations. Whether the observed differences provide clinical benefit for the macro- or microvascular complications of diabetes remains to be established.”
The China Study purported to show that vegetarians were healthier but totally misrepresented the data. See Denise Minger’s articles, cited below where she ran the raw data (available online) and removed confounding variables, getting significantly different information.
- Sugar, soluble carbohydrates, and fiber all had correlations with cancer mortality about seven times the magnitude of that with animal protein
- Both total fat and fat as a percentage of calories were both negatively correlated with cancer mortality
- Meat eaters in China tend to be better off and may be more urban than those with low amounts of animal foods. They are known to also eat more sugar and wheat which may be independent factors rather than the meat.
- Fish eating provinces in China have high rates of contamination with hepatitis B and shistosomiasis which are independent variables for cancer and do not necessarily apply to uncontaminated sources.
- The same data also shows living in a hot climate is highly correlated with low cancer. This exceeds the effect of animal protein by over 700% and may be correlated with low Vitamin D status
- When the data didn’t show correlations between diet and actual disease, Campbell used proxy factors like cholesterol levels to assume that disease was affected. This matters because for instance shistosomiasis raises cholesterol independently of diet.
- And of course, correlation is not causation. Not even the regressions that Minger ran on the raw China Study data show causation, although they do filter out some confounding factors. The data raises questions that should be studied in clinical trials. But it is imperative to fairly and accurately present the data, which is not done in Campbell’s book.
A study by Cho, et. al. showed that women in the Nurses Study who had the highest fat intake had the lowest cancer rates. This was purported to show that an Atkins-type diet was unhealthy, but the data differed significantly from the conclusions.
- Women who ate the most fat, the 5th quintile, had lower cancer rates than those who ate less fat (3rd and 4th quintiles.)
- Those with very low animal fat intake had the lowest cancer rates.
- The cancer rates in all quintiles was less than 1%, with rates between 0.68%-0.88% so differences are not really significant
- Similar studies do not differentiate saturated fat intake from vegetable sources which is more dangerous than from animal saturated fats which may have very different effects.
There have been a variety of ethnographic studies that try to look at vegetarian versus omnivorous diets. (There are no ethnographic studies of vegans since there are no vegan traditional diets.) These often are not of sufficient rigor to show such a comparison. Epidemological studies don’t prove causation, but they may suggest associations that can later be tested.
The Kenyan Maasai and the Kikuyu, live in the same country, climate, and the environment. The Maasai, were wholly carnivorous, drinking only the blood and milk of their cattle, and were tall, slim, healthy and long-lived. The Kikuyu, were wholly vegetarian, with stunted growth, high rates of disease, more visceral fat and shorter lives. Since the 1960s the Kikuyu have increased animal protein and are healthier while the Massai have incorporated corn and beans and now have more disease according to a 1996 study.
A similar study of the Inuit showed that the Inuit of Baffin Island and Greenland who ate a diet primarily of fish and meat had better health than the omnivorous Inuit of Lapland. However the latter tribe was adopting a western diet with junk food so the study does not prove anything other than that modern western diets are less healthy than fish and meat diets.
Other comparisons such as the higher rate of diabetes in Indian vegetarians versus Chinese omnivores have too many variables to consider them as useful. There are similar studies comparing vegetarian South Indians to omnivorous people in the north of India, and while the latter have better health, they also have different environments, cultures and ethnicity.
While there is no conclusive data that eating meat is harmful, there is significant evidence that eating poor quality food does impact health. The majority of studies that compare vegetarians to omnivores do not select omnivores with similar interests in healthy lifestyles. A study that looks at exercise, variety of vegetable consumption, high quality food, and degree of knowledge about health might find very different results. There is ample evidence that a paleloithic diet which is low in gluten and grains and high in vegetables and quality meats is healthy. Comparing such a diet to a vegetarian diet might yield more meaningful results.
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