Ask most people what causes heart disease and they will point to cholesterol. For the last 30 years we have been told about the dangers of eggs, beef, butter and cream. Yet according to one of the country's leading experts on heart disease, Dr. Meir Stampfer of Harvard, most patients who suffer heart attacks have normal cholesterol levels.
For decades, scientists have been tracking another substance in the blood as a potential culprit in heart disease. Few people have ever heard about homocysteine, but the more it is studied, the more dangerous it looks.
The most recent research comes from the famous Framingham Heart Study and was published in the New England Journal of Medicine.
The investigators found that the more homocysteine in the blood, the more likely people were to have clogged carotid arteries in the neck. This confirms previous work that showed an association between homocysteine and heart disease.
It has been more than 25 years since the first report linked this amino acid to atherosclerosis. Yet few patients are ever tested for homocysteine levels or told that diet may have an impact.
Homocysteine is formed in the body when animal protein is broken down. The more meat you eat, the more likely you are to have high levels of this compound.
On the other hand, a diet rich in folic acid and vitamin B-6 appears to lower homocysteine.
Foods rich in these vitamins include spinach, collard greens, split peas, liver, brewer's yeast, broccoli, peanuts, sweet potatoes and cauliflower.
Vegetarians have a lower risk of heart disease. This has often been attributed to the lack of animal fat and cholesterol in their diets. An alternate explanation might be that lack of animal protein should lead to lower levels of homocysteine. In addition, they have a higher intake of folic acid and vitamin B-6 from vegetable sources.
The recommended dietary allowance (RDA) for folic acid used to be 400 micrograms per day. This level is considered adequate to keep homocysteine levels under control for most people. Unfortunately, the RDA for folic acid was recently lowered to around half its previous amount. Many people don't consume even that much.
For those who would rather not restrict their meat consumption or eat lots of green leafy vegetables, vitamin supplements may be prudent. There is no solid evidence yet that extra folic acid and vitamin B-6 will reduce the risk of clogged arteries and heart attacks. Nevertheless, Dr. Stampfer suggests that while we await further research, "It will be prudent to insure adequate dietary intake of folate."
If you would like more information on cholesterol, homocysteine and other ways to protect your heart, you can request our Guide to Heart Health. Send $2 with a long (No. 10) stamped, self-addressed envelope to Graedons' People's Pharmacy, No. C-3, P.O. Box 52027, Durham, N.C. 27717-2027.
Joe Graedon is a pharmacologist. Dr. Teresa Graedon is medical anthropologist and nutrition expert.