Investigation into the relationship between diet and heart disease are limited by ethics and expense: Researchers can’t very well haveone group of people eating lots of cholesterol-laden food for decadesand maintain antoerh group on a low-cholesterol diet. By quilting together animal studies, epidemiological research and small-scale orotherwise limited human experiments, scientists have hypothesized alink, but debate continues (SN: 12/22 ; 29/84, p. 390).
Two studies in the March 28 NEW ENGLAND JOURNAL OF MEDICINE comedown on the side of such a link, but neither alone is likely to be thefinal word. In one study from Leiden University in the Netherlands, 39 men withat least one coronary artery choked to less than half its diameter bycholesterol deposits were placed on vegetarian diets to lowercholesterol levels in their blood. After two years, X-ray studies oftheir hearts revealed no increased obstruction in 18 of the 39 men,which, the researchers reports, indicates that “dietaryintervention may reduce the rate of coronary lesion growth.” Since the study involved snaking a catheter into the heart toassess the blockage — a procedure that carries a small risk — nocontrol group was followed. The researchers admit that this limits theusefulness of the study. In an accompanying editorial, David H.
Blankenhorn of the University of Southern California in Los Angelesnotes the same lack but observes that the study “provides the onlydirect information we have relating a defined diet to measured changesin coronary lesions.” The second report involved 1,001 middle-aged men in theIreland-Boston Diet-Heart study, a novel data base that includes men inIreland, brothers of these men who moved to Boston, and Boston sons ofIrish immigrants. The three groups had about the same rate of heart disease-relateddeath. However, when the researchers looked back at 20-year-old recordsof what the men had said they were eating at the study’s outset,they found that those men with high-cholesterol diets — wherever theylived — were more likely to develop heart disease. The finding,conclude the scientists from Harvard University in Boston and Trinityand University colleges in Dublin, “supports the hypothesis thatdiet is related, albeit weakly, to the development of coronary heartdisease.
” The Ireland-Boston study shows that equations taking into accounthow much and what kinds of food are eaten are as predictive of heartdisease as is smoking, Blankenhorn told SCIENCE NEWS. Other researchers, who had not yet seen the reports, were unwillingto comment on ptheir importance. But W. Virgil Brown, anatherosclerosis expert at the Mt.
Sinai School of Medicine in New York,when told some of the details of the Dutch study, said, “I would bevery hesitant to make too much of that.” The studies, notes Blankenhorn, “support the need for a changein the national diet and indicate merit for vegetarian diets.”But, he observes, “there is sufficient acknowledged weakness inboth studies to provide grounds for rebuttal by dedicated meat eatersand oponents of a national diet change.” Stay tuned.