• Dietary adherence in the Women's Health Initiative Dietary Modification Trial

      2004-04-01
      This article describes adherence to a low-fat dietary pattern (less than 20% energy from fat, five or more fruit/vegetable and six or more grain servings daily) in Years 1 and 5 of the Women's Health Initiative Dietary Modification Trial, which was designed to examine the effects of a low-fat dietary pattern on risk of breast and colorectal cancers and other chronic diseases in postmenopausal women. Participants were randomly assigned to a low-fat dietary intervention arm (40%, n=19,542) or a usual diet control arm (60%, n=29,294). Women in the intervention arm completed 18 group sessions during the first year, followed by quarterly annual maintenance sessions. Adherence was assessed as control minus intervention (C-I) group differences in percent total energy from fat as estimated by a food frequency questionnaire. Based on these self-reported dietary data, mean C-I was 10.9 percentage points of energy from fat at Year 1, decreasing to 9.0 at Year 5. Factors associated with poorer adherence were being older, being African American or Hispanic (compared with white), having low income, and being obese. Group session attendance was strongly associated with better dietary adherence. There are many limitations of self-reported dietary data, particularly related to social desirability and intervention-associated bias. Nonetheless, these data indicate that long-term dietary change was achieved in this clinical trial setting and reinforce the potential of the ongoing trial to answer questions of public health importance. UMMS researchers Judith Ockene and Milagros Rosal are Women's Health Initiative Study Investigators.
    • Nutritional and socioeconomic factors in relation to prostate cancer mortality: a cross-national study

      Hebert, James R.; Hurley, Thomas G.; Olendzki, Barbara C.; Teas, Jane; Ma, Yunsheng; Hampl, Jeffrey S. (1998-11-12)
      BACKGROUND: Large international variations in rates of prostate cancer incidence and mortality suggest that environmental factors have a strong influence on the development of this disease. The purpose of this study was to identify predictive variables for prostate cancer mortality in data from 59 countries. METHODS: Data on prostate cancer mortality, food consumption, tobacco use, socioeconomic factors, reproductive factors, and health indicators were obtained from United Nations sources. Linear regression models were fit to these data. The influence of each variable fit in the regression models was assessed by multiplying the regression coefficient b by the 75th (X75) and 25th (X25) percentile values of the variable. The difference, bX75 - bX25, is the estimated effect of the variable across its interquartile range on mortality rates measured as deaths per 100000 males aged 45-74 years. Reported P values are two-sided. RESULTS: Prostate cancer mortality was inversely associated with estimated consumption of cereals (bX75 - bX25 = -7.31 deaths; P = .001), nuts and oilseeds (bX75 - bX25 = -1.72 deaths; P = .003), and fish (bX75 - bX25 = -1.47 deaths; P = .001). In the 42 countries for which we had appropriate data, soy products were found to be significantly protective (P = .0001), with an effect size per kilocalorie at least four times as large as that of any other dietary factor. Besides variables related to diet, we observed an association between prostate cancer mortality rates and a composite of other health-related, sanitation, and economic variables (P = .003). CONCLUSIONS: The specific food-related results from this study are consistent with previous information and support the current dietary guidelines and hypothesis that grains, cereals, and nuts are protective against prostate cancer. The findings also provide a rationale for future study of soy products in prostate cancer prevention trials.
    • Predictors of dietary change and maintenance in the Women's Health Initiative Dietary Modification Trial

      Tinker, Lesley F.; Rosal, Milagros C.; Young, Anne F.; Perri, Michael G.; Patterson, Ruth E.; Van Horn, Linda; Assaf, Annlouise R.; Bowen, Deborah J.; Ockene, Judith K.; Hays, Jennifer; et al. (2007-07-01)
      OBJECTIVE: To identify predictors of dietary change to and maintenance of a low-fat eating pattern (or = 5 servings fruits/vegetables daily, and > or = 6 servings grains daily) among a cohort of postmenopausal women. Candidate predictors included intrapersonal, interpersonal, intervention program characteristics, and clinical center. DESIGN: Longitudinal study within the Women's Health Initiative Dietary Modification Trial. Dietary change was evaluated after 1 year of participation in the Women's Health Initiative Dietary Modification Trial, and dietary maintenance after 3 years. SUBJECTS: Postmenopausal women aged 50 to 79 years at baseline who were randomized to the intervention arm of the Women's Health Initiative Dietary Modification Trial (n=19,541). STATISTICAL ANALYSIS: Univariate and multivariate linear regression analysis was performed and associations evaluated between candidate predictors and each of the three dietary goals: percent energy from fat, fruit/vegetable servings, and grain servings. RESULTS: Year 1 (change) predictors of percent energy from fat (PCONCLUSIONS: The strongest predictors of dietary change and maintenance were attending intervention sessions and self-monitoring dietary intake. Novel was the finding that optimism predicted dietary change.