Review of Nutrition Article - Vitamin D Supplementation...

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Vitamin D Supplementation Vitamin D Supplement Question What is the Vitamin D status as indicated by serum 25(OH)D of Canadian men and women 35+ from seven cities across Canada in the randomly selected, population-based Canadian Multi- Center Osteoporosis Study (CaMos)? Chosen Article 25-Hydroxyvitamin D in Canadian adults: biological, environmental, and behavioral correlates Study Design and Subject Recruitment The study addresses a clear and well defined question (see above), which is relevant to the question of whether a major campaign should be initiated to improve vitamin D status and reduce the risk of osteoporosis. Data for this study come from the Canadian Multicenter Osteoporosis Study (CaMos), an ongoing longitudinal, population-based cohort study in nine Canadian-city based centers. It includes 9423 non-institutionalized, randomly selected men and women aged 25 years and older on entry into the study in 1995-1997. Furthermore, the study is also recent and employed a final population of 577 men and 1335 women 35+ years from seven cities across Canada from randomly selected CaMos. The analyses for this cross-sectional study are of data and sera gathered from participants at seven centers (Vancouver, Calgary, Saskatoon, Toronto, Kingston, Quebec City, and Halifax) between 2005 and 2007 (at 10-year follow up). The analyses are
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Vitamin D Supplementation restricted to adults aged 35+ years. A small portion of participants (5.8%, n=110) were assessed after 2007. To our knowledge, this is a relatively large number of randomized subjects from multiple parts of Canada for investigating vitamin D status, increasing the external validity of this study. Participation 42.5% of eligible household participants completed the full survey and 27.5% refused. A further 30% completed a refusal questionnaire which included demographic, fracture, osteoporosis information. The full responders were found to be similar, with respect to risk factors for osteoporosis, to those additional individuals who only partially participated. Non-response bias was negligible with respect to bone health, which is affected by 25(OH)D concentration. Non-response bias was of concern minimally in elder women and men over 80 years of age. Of those eligible to follow up at year 10 follow-up, the full survey completion rate for these centers was 83.1%. When excluding known deaths after baseline (1995-1997), 66.2% of the participants from the previous seven centers were still in the study after 10 years. The cohort included the 577 male and 1335 female full participants who gave blood samples, were measured for height and weight, and completed a comprehensive questionnaire which included data on demographics, diet, and supplement use, sun exposure and physical activity. Participants who did not give blood were excluded. Outcome Measurement
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Review of Nutrition Article - Vitamin D Supplementation...

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