Scientific Updates
By Reed Mangels, Ph.D., R.D.
MAYBE IT'S NOT ONLY THE CHOLESTEROL IN RED MEAT
Scientists have known for some time that women, prior to menopause, have much lower
rates of heart disease than men do. This has traditionally been explained by a
protective effect of the female hormone, estrogen. A study of Finnish men suggests
that the different rate of heart disease may actually be due to women's lower iron
levels. (Pre-menopausal women have lower iron levels because of losses of blood and
iron each month.)
Iron, while an essential nutrient, promotes production of oxidizing agents which can lead to the development of atherosclerosis. In the Finnish study, those men who had high levels of serum ferritin, a measure of stored iron, had a higher risk of having a heart attack than did men who had lower serum ferritin levels. Interestingly, meat consumption was closely linked to serum ferritin levels. So, perhaps it is the iron in red meat, rather than (or along with) its fat and cholesterol content, which explains the link between high meat consumption and risk of heart disease.
The results of this study suggest that, while it is important to consume enough iron so that iron deficiency anemia does not develop, excess iron is not desirable. The study's authors suggest that current dietary recommendations for iron be lowered for men and possibly for post-menopausal women. (For more information see: Salonen JT, Nyyssonen K, Korpela H., Tuomilehto J, Seppanen R, Salonen R: High stored iron levels are associated with excess risk of myocardial infarction in eastern Finnish men. Circulation 86:8803-11, 1992, and Sullivan JL: Stored iron and ischemic heart disease. Empirical support for a new paradigm. Circulation 86:1036-7, 1992.)
IS AN APPLE A DAY ENOUGH?
Vegetarians have lower rates of several kinds of cancer compared to the general
population. Many ideas have been offered as the reasons for these lower rates
including less smoking and dietary differences. Proposed dietary differences include
higher fiber and lower fat consumption by vegetarians. In addition, vegetarians may
eat more fruits and vegetables than non-vegetarians.
Researchers at the National Cancer Institute completed a massive review of scientific articles looking at fruit and vegetable consumption and cancer incidence. They concluded that out of 156 studies, 128 found significant protection from many kinds of cancer associated with generous intakes of fruits and vegetables.
In most kinds of cancer, the 25% of the population with the lowest intake of fruits and vegetables had about twice the risk of cancer compared to those with higher amounts of fruits and vegetables in their diets. A lot of attention has been focused on the role of individual nutrients (vitamin C, beta-carotene, etc.) in cancer prevention. These authors suggest that it may be more important to promote consumption of fruits and vegetables — nature's way of packaging a variety of important nutrients in foods — instead of searching for a single "magic bullet" nutrient.
Based on these results, both vegetarians and non-vegetarians should eat at least 5, and preferably more, servings of fruits and vegetables daily to reduce cancer risk. Currently only about 10% of the U. S. population meets this recommendation. How's your diet?
So, no, an apple a day isn't enough unless its accompanied by a grapefruit, some carrots, a potato, spinach... (See Block G, Patterson B, Subar A: Fruit, vegetables and cancer prevention: A review of the epidemiologic evidence, Nutr Cancer 18:1-29, 1992.)
