Since the popularity of the Atkins Diet, South Beach Diet and other high protein diets, many Americans are avoiding carbohydrates in favor of meat and high fat dairy sources such as cheese. Little information is available on the long-term effects of these diets on human health although studies show a strong correlation between countries with high animal protein intake and coronary heart disease [CHD], although short-term ecologic studies show a favorable effect on blood fats and a lower risk of ischemic (decreased blood flow to the heart) heart disease.

A 20-year follow-up study of over 25,000 California Seventh-day Adventists showed a positive association between meat consumption and ischemic heart disease. A 14-year follow-up study in over 80,000 women showed a significant increased risk of major CHD events. In that same study, a subgroup of over 57,000 postmenopausal women showed that processed meats, such as hog dogs, bacon, sausage, salami, and bologna, was associated with a 44% increased risk of CHD.

Studies on that animal protein fed to rabbits increase plaque formation in the arteries independent of dietary fat and cholesterol, whereas soy protein fed to rabbits did not show such a relationship, and other studies consistently show the positive effect soy protein has on blood fats. More recently, studies have shown a positive association between consumption of meat that has been fried, barbecued, or broiled with the development of several cancers, where the connection is explained by the creation of potent and bioavailable carcinogenic heterocyclic amines.

A study in the February issue of the American Journal of Epidemiology examined the long-term relationship of protein intake of over 29,000 postmenopausal women followed over 15 years. The authors found that there was a 30% increased risk of CHD in the group that had the highest animal protein intake compared to the group that had more vegetable protein. The authors also found that, “A composite of red and processed meat servings in place of carbohydrate food servings was associated with a 44 percent increase risk of CHD mortality, and a similar increased risk was observed with dairy servings.”

The authors note that the increased risk of CHD may be because animal protein contains large amounts of methionine. Methionine is an amino acid that eventually increases homocysteine levels in the body. Homocysteine has been shown in many studies to be a significant risk factor in heart disease.

The authors conclude that, “our results, together with the lack of benefit to sustained weight loss due to consumption of high-animal-protein diet such as promoted by Atkins and tested in a recent randomized trial, do not support any salutary gain of these diets and suggest potential harm. Long-term adherence to popular high-protein diets, without discrimination toward protein source, may have potentially adverse health consequences.”[HealthSentinel.com]