The [i]American Journal of Epidemiology[/i] recently published online two studies that are based on data from the Women’s Health Initiative Observational Study (WHIOS). The first one creates a platform for the upcoming national US dietary recommendations . Four commonly used diet quality indices – the Healthy Eating Index 2010 (HEI), the Alternative Healthy Eating Index 2010 (AHEI), the Alternate Mediterranean Diet (aMED), and the Dietary Approaches to Stop Hypertension (DASH) – are known to be related to the risks of death from all causes, cardiovascular disease (CVD), and cancer among postmenopausal women. The WHIOS prospective cohort study included 63,805 participants (from 1993 to 2010) who completed a food frequency questionnaire at enrolment, which collected data on frequency of intake and portion sizes for 122 foods and food groups during the past 3 months. Multivariate hazard ratios and 95% confidence intervals for death associated with increasing quintiles of diet quality index scores were estimated. During 12.9 years of follow-up, 5692 deaths occurred, including 1483 from CVD and 2384 from cancer. Across indices and after adjustment for multiple covariates, having better diet quality (as assessed by HEI, AHEI, aMED, and DASH scores) was associated with statistically significant 18–26% lower all-cause and CVD mortality risk. Higher HEI, aMED, and DASH (but not AHEI) scores were associated with a statistically significant 20–23% lower risk of cancer death. These results suggest that postmenopausal women consuming a diet in line with [i]a priori[/i] diet quality indices have a lower risk of death from chronic disease.
The second study looked into the energy balance rather than the diet alone, namely calculating the inflow and outflow of calories from one’s body . Data were abstracted from the whole cohort in regard to dietary habits (frequency of intake and portion sizes for 122 foods and food groups during the past 3 months) and physical activity (frequency and duration of walking activity outside the home, as well as other mild, moderate, or strenuous recreational activities, expressed as MET-hour per week). A smaller subgroup was included in the Nutrition and Physical Activity Assessment Study (NPAAS), where several additional metabolic parameters were collected and analyzed. Overall, calibrated energy consumption was found to be positively related, and activity-related energy expenditure (AREE) inversely related to the risks of various CVD, cancers, and diabetes. Estimated hazard ratios for 20% increases in total energy consumption and AREE, respectively, were as follows: 1.49 (95% CI 1.18–1.88) and 0.80 (95% CI 0.69–0.92) for total CVD; 1.43 (95% CI 1.17–1.73) and 0.84 (95% CI 0.73–0.96) for total invasive cancer; and 4.17 (95% CI 2.68–6.49) and 0.60 (95% CI 0.44–0.83) for diabetes. Simultaneous total energy consumption and AREE changes of these magnitudes are associated with an approximately 50% lower risk of major CVD and cancers and an approximately 7-fold lower diabetes incidence.
Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
George SM, Ballard-Barbash R, Manson JE, et al. Comparing indices of diet quality with chronic disease mortality risk in postmenopausal women in the Womens Health Initiative Observational Study: evidence to inform National Dietary Guidance. Am J Epidemiol 2014 July 17. Epub ahead of print
Zheng C, Beresford SA, Van Horn L, et al. Simultaneous association of total energy consumption and activity-related energy expenditure with risks of cardiovascular disease, cancer, and diabetes among postmenopausal women. Am J Epidemiol 2014 Jul 12. Epub ahead of print