VITamins And Lifestyle Cohort Study: Study Design and Characteristics of Supplement Users

Abstract

Vitamin and mineral supplements are among the most commonly used drugs in the United States, despite limited evidence on their benefits or risks. This paper describes the design, implementation, and participant characteristics of the VITamins And Lifestyle (VITAL) Study, a cohort study of the associations of supplement use with cancer risk. A total of 77,738 men and women in western Washington State, aged 50-76 years, entered the study in 2000-2002 by completing a detailed questionnaire on supplement use, diet, and other cancer risk factors, and 70% provided DNA through self-collected buccal cell specimens. Supplement users were targeted in recruitment: 66% used multivitamins, 46% used individual vitamin C, 47% used individual vitamin E, and 46% used calcium, typically for 5-8 of the past 10 years. Analyses to identify confounding factors, the main study limitation, showed that regular nonsteroidal anti-inflammatory drug use, intake of fruits and vegetables, and recreational physical activity were strongly associated with supplement use (p < 0.001). The authors describe a follow-up system in which cancers, deaths, and changes of residence are tracked efficiently, primarily through linkage to public databases. These methods may be useful to other researchers implementing a large cohort study or designing a passive follow-up system.

Effects of physical activity intensity, frequency, and activity type on 10-y weight change in middle-aged men and women

“…Methods for the VITAL study have been described in detail elsewhere. 8 Briefly, 364 418 baseline questionnaires were mailed between October 2000 and December 2002 to men and women aged 50 to 76 y who lived in western Washington State. Of the 79 300 questionnaires that were returned, 77 738 passed eligibility and questionnaire quality control.…”

Diabetes and the risk of prostate cancer: the role of diabetes treatment and complications

“…Recruitment for the cohort occurred by mail between October 2000 and December 2002, using names purchased from a commercial mailing list. Further details of study methods are given in White et al 16 Among eligible men, the response rate was 20.6%, for a total of 37 382 participants. Of these, 2141 men who reported a history of prostate cancer on the baseline questionnaire or who left that section or the diabetes section of the questionnaire blank were excluded, as were two men subsequently diagnosed with in situ prostate cancer, yielding a total of 35 239 men for this analysis.…”

Mortality outcomes associated with intake of fast-food items and sugar-sweetened drinks among older adults in the Vitamins and Lifestyle (VITAL) study

“…Baseline surveys querying supplement use, health history, cancer risk factors, diet and demographic information were completed by 77 718 individuals who were enrolled in the study between 2000 and 2002. Details of the study design and sample characteristics are reported elsewhere (32) . Dietary behaviours were assessed via a semiquantitative FFQ; participants were excluded from the analysis if they reported gastrointestinal malabsorption disorders or gastric bypass surgery (n 45) or if they failed more specific FFQ quality control checks (i.e.…”