The Women's Health Initiative Dietary Modification trial: overview and baseline characteristics of participants

Calcium plus vitamin D supplementation and the risk of colorectal cancer

BACKGROUND

Higher intake of calcium and vitamin D has been associated with a reduced risk of colorectal cancer in epidemiologic studies and polyp recurrence in polyp-prevention trials. However, randomized-trial evidence that calcium with vitamin D supplementation is beneficial in the primary prevention of colorectal cancer is lacking.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial involving 36,282 postmenopausal women from 40 Women's Health Initiative centers: 18,176 women received 500 mg of elemental calcium as calcium carbonate with 200 IU of vitamin D3 [corrected] twice daily (1000 mg of elemental calcium and 400 IU of vitamin D3) and 18,106 received a matching placebo for an average of 7.0 years. The incidence of pathologically confirmed colorectal cancer was the designated secondary outcome. Baseline levels of serum 25-hydroxyvitamin D were assessed in a nested case-control study.

RESULTS

The incidence of invasive colorectal cancer did not differ significantly between women assigned to calcium plus vitamin D supplementation and those assigned to placebo (168 and 154 cases; hazard ratio, 1.08; 95 percent confidence interval, 0.86 to 1.34; P=0.51), and the tumor characteristics were similar in the two groups. The frequency of colorectal-cancer screening and abdominal symptoms was similar in the two groups. There were no significant treatment interactions with baseline characteristics.

CONCLUSIONS

Daily supplementation of calcium with vitamin D for seven years had no effect on the incidence of colorectal cancer among postmenopausal women. The long latency associated with the development of colorectal cancer, along with the seven-year duration of the trial, may have contributed to this null finding. Ongoing follow-up will assess the longer-term effect of this intervention. (ClinicalTrials.gov number, NCT00000611.).

Improving dietary self-monitoring and adherence with hand-held computers: a pilot study

PURPOSE

Innovations in information technology offer new opportunities for creative application of personalized, tailored feedback strategies for improving dietary adherence. We developed and tested a real-time diet-monitoring and feedback system using hand-held computers. The goals were to increase diet self-monitoring, reduce the burden of monitoring food intake, and increase adherence to dietary goals within a clinical trial.

METHODS

Participants were 33 women in the Diet Modification arm of the Women's Health Initiative (WHI). After using focus groups to determine system features, women used the Personal Digital Assistant (PDA)-based system for 1 month and received immediate and weekly tailored feedback. The process and outcomes were evaluated using real-time food records collected through the PDAs; surveys; and self-reported food frequency questionnaires.

RESULTS

Participants significantly increased self-monitoring, improved their attitudes toward self-monitoring, and met their dietary goals more often. Reported total fat intake and percent energy from fat decreased significantly. There was a modest decrease in mean caloric intake.

DISCUSSION

The pilot study findings support the largely untapped potential of hand-held computers for improving diet monitoring and diet adherence, particularly within a clinical trial.

Publishing Nutrition Research: A Review of Study Design, Statistical Analyses, and Other Key Elements of Manuscript Preparation, Part 1

To enhance the Journal's position as the premier source for peer-reviewed research in the science of food, nutrition, and dietetics, members of the Board of Editors recognize the importance of providing a resource for researchers to ensure quality and accuracy of reporting in the Journal. This first monograph of a periodic four-part series focuses on the study hypothesis, study design, and collaboration with a statistician. The basics of study design start with a clear hypothesis or research question and a definitive outcome measure. Throughout the development of a research project, the questions of what is to be discovered and why the research is being conducted need to be addressed. Decisions about parameters to measure and study design most appropriate to test a hypothesis create the foundation for future conclusions. Collaboration with a statistician can aid in the research development process. Documentation that coherently communicates the research process will advance the science of evidence-based practice in nutrition and dietetics. Real examples from published literature are provided, as well as references to books and online resources.

Mediterranean diet, antioxidants and cancer: the need for randomized trials

In nutritional epidemiology the traditional approach has been to assess single nutrients or food items. Now, a growing interest exists in dietary patterns. The study of dietary patterns with a whole-diet approach represents a needed and complementary methodology. Among a priori defined patterns, the highly palatable traditional Mediterranean diet has many options to be the first choice in the dietary prevention of cancer. However, sound epidemiologic evidence about its ability to prevent the most frequent cancers is scarce. In conjunction with large and well-designed cohort studies, randomized trials using a whole-diet approach and not a simple antioxidant supplement are needed in Mediterranean countries.