The construct validity and the test-retest reliability of a self-administered questionnaire about habitual physical activity were investigated in young males (n = 139) and females (n = 167) in three age groups (20 to 22, 25 to 27, and 30 to 32 yr) in a Dutch population. By principal components analysis three conceptually meaningful factors were distinguished. They were interpreted as: 1) physical activity at work; 2) sport during leisure time; and 3) physical activity during leisure time excluding sport. Test-retest showed that the reliability of the three indices constructed from these factors was adequate. Further, it was found that level of education was inversely related to the work index, and positively related to the leisure-time index in both sexes. The subjective experience of work load was not related to the work index, but was inversely related to the sport index, and the leisure-time index in both sexes. The lean body mass was positively related the the work index, and the sport index in males, but was not related to the leisure-time index in either sex. These differences in the relationships support the subdivision of habitual physical activity into the three components mentioned above.

The relative validity of a 104-item food-frequency method to assess intakes of fats and cholesterol was tested against the dietary history of 191 men and women. Pearson correlation coefficients ranged from 0.38 for linoleic acid (% of energy) to 0.83 for energy intake, with 0.78 and 0.75 for the intakes of total fat and saturated fatty acids, respectively. Mean intakes were overestimated by the food-frequency questionnaire relative to the dietary history by 5% for energy and monounsaturated fatty acids (% of energy) and up to 30% for linoleic acid intake. Linoleic acid concentrations in erythrocytes and adipose tissue were used as biomarkers of intake. The correlation of the linoleic acid intake according to the food-frequency questionnaire with linoleic acid in erythrocytes and adipose tissue was 0.44 and 0.28, respectively, and the dietary history gave similar values. The food-frequency questionnaire gives results similar to those from the dietary history and is thus considered appropriate for classifying subjects according to their fat intake.

Animal studies show favorable effects of n-3 fatty acids on inflammation and cancer, but results from epidemiologic studies appear to be inconsistent. The authors conducted meta-analyses of prospective cohort studies that evaluated the association between fish consumption or n-3 fatty acids and colorectal cancer incidence or mortality. Random-effects models were used, and heterogeneity between study results was explored through stratified analyses. The pooled relative risks for the highest compared with the lowest fish consumption category were 0.88 (95% confidence interval: 0.78, 1.00) for colorectal cancer incidence (14 studies) and 1.02 (95% confidence interval: 0.90, 1.16) for colorectal cancer mortality (four studies). The pooled relative risks for colorectal cancer incidence were 0.96 (95% confidence interval: 0.92, 1.00) for each extra occurrence of fish consumption per week (seven studies) and 0.97 (95% confidence interval: 0.92, 1.03) for each extra 100 g of fish consumed per week (four studies). Stratified analysis showed that the pooled relative risk for colorectal cancer incidence was more pronounced for women and in studies with a large exposure contrast. In cohort studies, fish consumption was shown to slightly reduce colorectal cancer risk. Existing evidence that n-3 fatty acids inhibit colorectal carcinogenesis is in line with these results, but few data are available addressing this association.

The single and combined effects of three healthy lifestyle behaviors-nonsmoking, being physically active, and having a high-quality diet-on survival were investigated among older people in the SENECA Study. This European longitudinal study started with baseline measurements in 1988-1989 and lasted until April 30, 1999. The study population consisted of 631 men and 650 women aged 70-75 years from Belgium, Denmark, Italy, The Netherlands, Portugal, Spain, and Switzerland. A lifestyle score was calculated by adding the scores of the lifestyle factors physical activity, dietary quality, and smoking habits. The single lifestyle factors and the lifestyle score were related to mortality. Even at ages 70-75 years, the unhealthy lifestyle behaviors smoking, having a low-quality diet, and being physically inactive were singly related to an increased mortality risk (hazard ratios ranged from 1.2 to 2.1). The risk of death was further increased for all combinations of two unhealthy lifestyle behaviors. Finally, men and women with all three unhealthy lifestyle behaviors had a three- to fourfold increase in mortality risk. These results underscore the importance of a healthy lifestyle, including multiple lifestyle factors, and the maintenance of it with advancing age.

Our findings are consistent with the notion that malaria-induced hemolysis is accompanied by increased erythropoiesis. Serum transferrin receptor concentration is not useful for detecting iron deficiency in individuals with malaria. Individuals with high concentrations of serum C-reactive protein or similar acute phase reactants should be excluded from analysis if serum ferritin concentrations <12 microg/L are to be used to measure iron deficiency in malaria-endemic areas.