In the most comprehensive scientific report on diet and health to date, the National Research Council on Wednesday called for broad changes in American eating habits and gave specific recommendations to eat much less fat, eat more fruits, vegetables and starches and avoid high-dose vitamin and mineral supplements.
The council recommended that people daily eat five or more half-cup portions of fruits and vegetables and a minimum of six portions of starches such as breads, cereals and beans. The recommendations would roughly double the average amounts of these items eaten by Americans.
The council also said it found no proof that calcium and fiber supplements confer any health benefit. While the panel did not conclude that daily vitamin-mineral supplements are harmful, it found no evidence that they are beneficial.
The recommendations were prepared by a committee of 19 diet and health experts created to resolve conflicting dietary advice that in recent years has come from various private and governmental bodies. The panel took three years to examine nearly 6,000 studies and compile a 1,400-page report that distills the various findings into one set of dietary guidelines.
Among other conclusions of the report were these:
--Evidence linking coffee to heart disease and cancer is inconclusive.
Urges Sugar Limits
--Sugar has not been established as a risk factor for any chronic disease other than cavities. Refined sugar, like that used in cakes and cookies, should be limited, however, since it contributes calories with no essential nutrients.
--Food additives do not appear to have contributed to the overall risk of cancer in humans.
--There is no evidence that pesticides or natural toxins in food contribute significantly to cancer risk in the United States. But the risks for simultaneous exposure to these compounds has not been adequately tested.
This is the first time that a committee of the National Research Council, the working arm of the National Academy of Sciences, has made such definitive dietary recommendations.
“Many people may be confused by the vast amount of advice given in many forms about what to eat,” said Dr. Arno G. Motulsky, chairman of the Committee on Diet and Health. “Some may have delayed making changes in their diets until they are more convinced that scientists have reached consensus. We hope our report will help these individuals move from inaction and complacency to action.”
The committee said the risk of heart disease could be reduced by at least 20% if the public followed the fat and cholesterol guidelines. Americans currently consume 37% of their calories as fat. The committee endorsed a reduction to 30%--as many other health groups have recommended--but it acknowledged that level is only “moderately” low in fat and said further reductions would provide additional benefits.
The committee also said the risk of cancer of the colon, lung and stomach could be reduced by sharply increasing consumption of fruits and vegetables, particularly citrus fruits and green and yellow vegetables.