for each of the following questions: 1) association among various population groups, 2) association among individuals within a population, 3) effect of intervention studies, 4) strength of animal models, and 5) a biological explanation. This five-point rating of the strength of association leading to assumption of cause and effect is based on the criteria of A.B. Hill (8) cited earlier. 45. When 10 diet-disease relationships were studied by this committee of nine experts: 1) the relationship of cholesterol to atherosclerosis, 2) saturated fat to atherosclerosis, 3) cholesterol plus saturated fat to atherosclerosis, 4) carbohydrate to atherosclerosis, 5) carbohydrate to diabetes, 6) carbohydrate to dental caries, 7) alcohol to liver disease, 8) alcohol to atherosclerosis, 9) salt to hypertension, and 10) excess calories to chronic disease generally, the ratings were less than unanimous. In fact, only 5 of the relationships were considered beyond doubt, i.e. reaching consensus, on a rating of greater than 85% or less than 15%. On a scale of 100, the relationship of carbohydrate to dental caries was given 87% with a small range. The relationship of alcohol to liver disease was given 88% with a very small range. The relationship of dietary carbohydrate to atherosclerosis, was given only 11% (89% against), carbohydrate and diabetes was given 13% (87% against), and alcohol and atherosclerosis was given 13% (87% against). So 5 out of the 10 propositions rated better than 85% for or against. 46. On the other hand, on issues on which many of the dietary goals and guidelines are based, agreement was less than consensus. The relationship of dietary cholesterol to coronary disease, was only given 62% with a range of 26-78%; saturated fat, only 58%, with a range of 30-72%; cholesteroland fat together only 73% with a range of 50-80%; and salt and hypertension, 74% with a range of 60-80%. Even excess calories and chronic disease averaged 68% with a range of 26-74%. I mention this to indicate that after this exaustive study most of the reviewers were uncertain about the controversial issues. All of the chapters end up with a statement that the risks and benefits of reducing or increasing the intake of a given factor in the American diet are unknown. 47. Atherosclerosis is a disease of unknown etiology. The "Lipid-Hypothesis" is not proved and as a strategy for reduction of CHD has failed. New excitement has been generated about the "Platelet Hypothesis" with advances in the knowledge of the relationship of platelet fatty acids to thromboxane formation and consequent platelet aggregation (30). Feeding aspirin and marine oils may provide a new strategy for prevention of coronary disease. 48. It is tempting to believe that a combination of small changes in a number of environmental factors, i.e. diet, smoking, physical exercise, and drugs for the treatment of hypertension may be responsible for the decrease in CHD mortality in the U.S. and elsewhere. Certainly diet is not responsible for much of the change. Other explanations are possible and the present controversy regarding the cause and effect relationship between environmental factors and CHD rates only underlines the need for more reserach into causation and development of new strategies for prevention of CID. References 1. Hand, D.B., Caso, E.K., Darby, W.J., Davidson, C.S., 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Food and Nutrition Board, "Toward Healthful Diets", National Committee on Dietary Allowances, Food and Nutrition Board, "Recommended Dietary Allowances", Ninth Revised Edition, National Academy of Sciences, Washington, D.C., 1980. Select Committee on Nutrition and Human Needs, U.S. Senate: AHA Committee Report, "Diet and Coronary Heart Disease", Council Report, "American Medical Association Concepts of U.S.D.A. Pamphlet, "Nutrition and Your Health, Dietary Guidelines for Americans", February, 1980. Hill, A.B., "The Environment and Disease: Association or Kannel, W.B. and Gordon, T., "The Framingham Diet Study: Nichols, A.B., Ravenscroft, C., Lanphier, D.E. and Ostrander, Brown, J. et al., "Nutritional and Epidemiologic Factors McMichael, Sir J., "Fats and Atheroma: an inquest", Brit. McMichael, Sir J., "Why Blame Cholesterol?", The Lancet, Mann, G.V., "Current Concepts, Diet-Heart: End of an Era", Corday, E. and S.R. Corday, "Prevention of Heart Diesease Facts", The Am. J. of Cardiology, 35, 330-333, 1975. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. "Can I avoid a Heart-attack?", Lancet Editorial 1, 605, 1974. Kannel, W.B., "Prevention of coronary heart disease by control of risk factors (questions and answers). J.A.M.A. 227, 338, 1974. Unproved Hypotheses", The Dawber, Ahrens, E.H., "Dietary Fats and Coronary Heart Disease: Unfinished Business", The Lancet, December 22/29, 1979. "Recommendations for prevention programs in relation to Nutrition and cardiovascular disease", Department of National Health and Welfare, June, 1977. "Pre Passmore, R., Hollingsworth, D.F., and Robertson, J., scription for a better British diet", Brit. Med. J., 1, 527531, 1979. Langsford, W.A., "A food and nutrition policy", Food and Molitor, G.T.T., Sweden, A. Bellwether of Future Policy Trends, in Critical Food Issues of the Eighties, Ed. (M. Chou and D.P. Harmon), pp. 66-93, Pergamon Press, New York, 1979. Havlik, R. and Reinleib, M., Editors, Proceedings of the Healthy People, The Surgeon General's Report on Health Promotion and Disease Prevention. DHEW, Public Health Service, 79-55071, July, 1979. Jones, H.B. A Special Consideration of the Aging Process, National Heart, Lung and Blood Institute, Five Year Findings Cornfield, J., "Joint dependence of risk of coronary heart Ahrens, E.H. and Connor, W.E., Chairmen, Task Force of the Dyerberg, J., Bang, H.O., Stifferson, E., Moncoda, S. and STATEMENT OF REUBEN L. JOHNSON DIRECTOR OF LEGISLATIVE SERVICES At the 78th annual convention of National Farmers Union held March 2-6, 1980, at Denver, Colorado, our delegates approved a policy resolution on "Dietary Guidance," which warned of dietary advice, based on incomplete or inconclusive research, and not warranted by facts. Referring particularly to the controversy about dietary cholesterol and heart disease, the National Farmers Union resolution urged that "care should be taken that premature conclusions are not drawn in diet and disease research to the detriment of both consumers and the producers of wholesome and nutritious food products." The National Farmers Union statement is attached in full. We were most pleased recently, upon having carefully examined the report of the Food and Nutrition Board, entitled "Toward Healthful Diets," to find that a very scientific and objective evaluation had been made of the most recent medical research in this field. The Food and Nutrition Board of the National Academy of Sciences, after all, has some undebatable credentials. For almost 40 years, it is the agency which has been issuing the widely recognized and respected "Recommended Dietary Allowance" (RDA) guidelines. We commend the Food and Nutrition Board for issuing its report because it is important for American consumers to be aware and to recognize that there is no clear-cut evidence that reducing blood levels of cholesterol by diet changes will significantly affect coronary heart disease and mortality. It is important for consumers to realize that there is no reason for the average healthy American to reduce consumption of dairy products, meat, eggs, and fats ' except as it may be necessary to achieve and maintain a desirable body weight. The report recommends that dietary change or therapy "should be undertaken under a physician's guidance," for such persons as have a "positive family history of heart disease and other risk factors, such as obesity, hypertension, and diabetes." The Board recommends that the adult American, whose body weight is under reasonable control, should feel free to "select a nutritionally adequate diet from the foods available, by consuming each day appropriate servings of dairy products, meats or legumes, vegetables and fruits, and cereal and breads." Significantly, the Board declares that it considers it "scientifically unsound to make single, all-inclusive recommendations to the public regarding intakes of energy, protein, fat cholesterol, carbohydrate, fiber, and sodium." Referring to the risk factors associated with cardiovascular disease, the report says that cause and effect have not been established. "Diet modification as recommended for the prevention of atherosclerosis is based upon assumptions not yet adequately tested," says the Board. "It has not been proven that lowering cholesterol levels by dietary intervention will consistently affect the rate of new coronary events." Importantly, the Board examined seven large-scale research studies carried out in London, Oslo, Helsinki, New York, New Jersey, and Los Angeles during the past two to ten years. Although decreases in serum cholesterol concentrations of 7 to 16 percent were achieved, the Board reports there was only a "marginal decrease in coronary disease incidence but no effect on overall mortality." The Board makes a sound judgment when it declares that "the American food supply on the whole is nutritious and provides adequate quantities of nutrients to protect essentially all healthy Americans from deficiency diseases." We believe that this Subcommittee would do a great service to the American people to reprint the entire text of "Toward Healthful Diets" report in the record of this hearing. It deserves a careful, unprejudiced reading by the American people. |