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  1. Is there a level of sunlight exposure that is sufficient to maintain adequate vitamin D levels but does not increase the risk of non-melanoma or melanoma skin cancer?

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

The review focused on electronic searches of the medical literature to identify publications addressing the aforementioned questions. Out of 9,150 citations, 112 RCTs, 19 prospective cohorts, 30 case–control studies, and 6 before-after studies were systematically reviewed, and each was rated on quality and used to assess the strength of evidence for each outcome.

The methods and results chapters of the AHRQ-Ottawa evidence review are reprinted below. The report in its entirety, including appendices and evidence tables, can be accessed and viewed at

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