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Chapter 2. Methods

Key Questions Addressed in This Report

The University of Ottawa EPC’s evidence report on Vitamin D is based on a systematic review of the scientific literature. A technical expert panel was recruited to help refine key questions and provide expertise to the review team during the review process. The finalized questions were:

  1. Are specific circulating concentrations of 25(OH)D associated with the following health outcomes in:

    1. Children: rickets, bone mineral density (BMD) or bone mineral content (BMC), fractures, parathyroid hormone (PTH)?

    2. Women of reproductive age (includes pregnant and lactating women): BMD, calcaneal ultrasound, fractures, calcium absorption, PTH?

    3. Elderly men and postmenopausal women: BMD, fractures, falls?

  1. Does dietary intake (fortified foods and/or vitamin D supplementation) or sun exposure affect circulating concentrations of 25(OH)D?

    1. Does this vary with different age groups, ethnicity, use of sunscreen, geography and/or body mass index (BMI)?

    2. What are the effects of fortified foods on circulating 25(OH)D concentrations?

    3. What is the effect of sun exposure and vitamin D supplementation on levels of serum 25(OH)D?

  1. What is the evidence regarding the effect of supplemental doses of vitamin D on bone mineral density, fractures and fall risk in:

    1. Women of reproductive age and postmenopausal women?

    2. Elderly men?

    3. Is there variation with baseline levels of 25(OH)D?

  1. Is there a level of sunlight exposure (time of year, latitude, BMI, amount of skin exposed) that is sufficient to maintain adequate vitamin D levels, but does not increase the risk of melanoma or non-melanoma skin cancer?

  2. Does intake of vitamin D above current reference intakes lead to toxicities (e.g., hypercalcemia, hypercalciuria, calcification of soft tissue or major organs, kidney stones)?

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