Physical Activity and Cancer: Lessons Learned from Nutritional EpidemiologyFriedenreich, Christine M.
doi: 10.1111/j.1753-4887.2001.tb06962.xpmid: 11720340
Convincing epidemiologic evidence currently exists for an association between physical activity and the prevention of colon and breast cancer. Physical activity may also reduce the risk of cancer at several other sites. With increasing research on this topic, it is apparent that studies of physical activity and cancer have numerous methodological similarities with studies of nutrition and cancer. Lessons learned from nutritional epidemiology that can be applied to studies of physical activity and cancer prevention and recommendations for future research are discussed in this review.
Micronutrients and Child Health: Studies in International Nutrition and HIV InfectionDuggan, Christopher; Fawzi, Wafaie
doi: 10.1111/j.1753-4887.2001.tb06963.xpmid: 11720341
Increasing data link micronutrient deficiencies to excess childhood morbidity and mortality, and similar relationships have been noted in the study of nutrition and HIV infection. We review epidemiologic studies that have examined the relationship between micronutrient deficiencies and health outcomes in childhood and HIV infection, as well as clinical trials of micronutrient supplementation. Vitamin A supplementation among communities at risk of deficiency effectively reduces mortality and morbidity in children younger than age 5, and vitamin A may be especially effective in HIV-infected children. Vertical transmission of HIV has not to date been affected by maternal micronutrient supplementation. In children with poor dietary zinc intake and/or bioavailability, zinc supplementation reduces the incidence and severity of diarrheal diseases, as well as the occurrence of pneumonia. Vitamin A therapy has not been associated with improved growth, whereas some trials have shown that zinc supplementation is associated with greater increments in height. Further trials of micronutrient supplementation are warranted.
Diet Image: a New Perspective on the Food-Frequency Questionnairedoi: 10.1111/j.1753-4887.2001.tb06964.xpmid: 11720342
Food-frequency questionnaires have become the dominant method for assessing dietary intakes in epidemiologic studies. However, their accuracy continues to be questioned. In a recent study, volunteers consumed three diets of varying fat content over 6 weeks. Compared with diet records, the food-frequency questionnaire provided less reliable estimates of the absolute amounts of fats and cholesterol consumed. Advocates of the food-frequency approach argue that attempting to validate the instrument against standard diets represented a highly contrived situation. In their view, food-frequency questionnaires critically depend on the participants' long-term knowledge of their own dietary patterns and are intended to measure intakes averaged over at least a year. That viewpoint tacitly acknowledges that food-frequency questionnaires have less to do with memory for what was consumed than with subjective inferences about the nature of the habitual diet. Food frequencies, much like food preferences or body image, appear to be a measure of attitude. As such, they may not be subject to absolute validation procedures.