Positive Health Online

Abstract

KUSHI, Division of Epidemiology, the University of Minnesota School of Public Health, Minneapolis 55454-1015 USA. kushi@epi.umn.edu. writes that the role of nutritional epidemiology studies in the development of nutritional recommendations has been controversial, partly because individual studies supporting either side of a given issue can often be identified .

Background

Several sets of criteria for inference of a causal relation between a dietary factor and a disease have been suggested. One, that of Sir Austin Bradford Hill, includes criteria such as strength of association, dose-response relation, consistency of association, temporally correct association, specificity of association and biological plausibility. Another set of criteria, used by the US Preventive Services Task Force, ranks evidence according to study design, designating evidence from randomised controlled trials as superior to evidence from cohort or case-control studies, which are in turn superior to evidence from ecological studies or opinions of respected authorities.

Methodology

The authors applies these criteria to the question of whether vitamin E intake is associated with coronary heart disease . The results suggest that the epidemiologic evidence from prospective cohort studies generally support an inverse association of vitamin E intake and risk of coronary heart disease. Information from randomised trials is limited, but also is suggestive of an inverse association with nonfatal, but not with fatal, coronary events . The application of criteria for causal inference to specific questions in nutritional epidemiology may provide clarity to seemingly contradictory information.

Results

Conclusion

References

Kushi LH. Vitamin E and heart disease: a case study. American Journal of Clinical Nutrition 69(6): 1322S-1329S. Jun 1999.