Osteoporosis Canada assessment for vitamin D3 supplementation is considerably higher than that with that of the American Institute of Medicine. Their higher dose recommendations is based on the data that a huge number of Canadians are deficient in vitamin D3. They argue for doses as high as 4,000 IU vitamin D3 for those with osteoporosis.
I do not know who belongs to Osteoporosis Canada so I do not know if they suffered the conflicts of interest at the American Institute of Medicine, but both are conservative or don’t know the current research evidence showing that vitamin D3, especially from sunlight has an effect on overall health, if not a crucial effect on your health.
They also included a small study comparing the amount of 25-hydroxyvitamin D3 produced when people use sunscreen or not. They saw no real difference and was such a small increase which indicates to me that the data are worthless. It was done earlier than 1995 when the SPF = 17. Obese people also trap vitamin D3 in their fat more efficiently than thinner people.
Jim Kawakami, Jan 15, 2011, http://jimboguy.blogspot.com
Hanley DA, Cranney A, Jones G, et al. Vitamin D in adult health and disease: a review and guideline statement from Osteoporosis Canada. CMAJ. 2010;182:E610-8. http://www.medscape.com/viewarticle/734963?src=ptalk
This study was selected from Medscape Best Evidence, which uses the McMaster Online Rating of Evidence System. Of a possible top score of 7, this study was ranked as 5 for newsworthiness and 7 for relevance by clinicians who used this system.
Also, as a key part of this review, we have included the following:
Dietary Reference Intakes for Calcium and Vitamin D, Institute of Medicine of the National Academies. National Academic Press. Washington, DC. Available at: http://books.nap.edu/openbook.php?record_id=13050
Many adults are deficient in vitamin D, placing them at elevated risk for fracture. But what is the ideal way to prevent this deficiency? And does the method used matter in terms of health outcomes? Osteoporosis Canada recently reviewed these issues and offers bold new recommendations for vitamin D supplementation. But their recommendations are quite different from those offered by the Institute of Medicine.
Vitamin D is important in the prevention of disease, but the degree of benefit associated with vitamin D is a matter of debate. Although the most obvious role of vitamin D is maintenance of bone health, research has suggested that it may also be important as a means to prevent cancer and falls among older adults. Moreover, many adults lack adequate levels of vitamin D. Recognizing this significant public health issue, Osteoporosis Canada recently released its recommendations for the assessment and management of vitamin D deficiency.
Vitamin D deficiency is more common than many physicians might believe. In a clinically relevant population of postmenopausal women, the prevalence of vitamin D deficiency was as low as 1.6% among community-dwelling women to as high as 86% among institutionalized women. Significant vitamin D deficiency was present in up to 76% of women with osteoporosis and 50%-70% of women with a history of fracture.
One of the challenges of reducing vitamin D deficiency across populations is determining the most appropriate source of the hormone. Most adults get the majority of their vitamin D stores from exposure to ultraviolet B radiation from the sun. This results in considerable variability in serum vitamin D levels among adults based on climate, latitude, and skin pigmentation. As a rough guide, the authors note that a young white person needs approximately 4 minutes of direct exposure to sunlight on the arms and legs to generate approximately 1000 IU of vitamin D3.
The fact that sunlight is the principal source of vitamin D creates a conflict for patients, particularly those with light skin: How to get enough sunlight to promote higher levels of vitamin D without increasing the risk for skin cancer? No clear consensus exists on this issue. One means to mitigate the potentially harmful effects of sunlight is the use of sunscreen. Although some research has suggested that sunscreen reduces the synthesis of vitamin D, a randomized trial of 113 Australian citizens found that serum levels of 25-hydroxyvitamin D3 (25-OH-D) increased by similar amounts over 1 summer whether sunscreen or a placebo was used. … http://www.medscape.com/viewarticle/734963?src=ptalk
Small Australian Study Indicates Regular Sunscreen, SPF 17, Does Not Have a Large Effect on Serum 25-Hydroxy-Vitamin D Metabolite, Medline Abstract Arch Dermatol. 1995: 131 (4):415-21 (ISSN: 0003-987X), Marks R; Foley PA; Jolley D; Knight KR; Harrison J; Thompson SC
Department of Dermatology, St Vincent's Hospital, University of Melbourne, Fitzroy, Victoria.
BACKGROUND AND DESIGN: Studies published have suggested a possibility that regular use of sunscreen to prevent skin cancer may put the population, particularly elderly people, at risk of vitamin D deficiency. …
A randomized double-blind control trial of the daily use of a broad-spectrum sunscreen (sun protection factor [SPF] 17) vs placebo cream over a summer period in Australia was conducted in 113 people aged 40 years and over, with sampling stratified by age. All participants had at least one solar keratosis.
Serum samples taken at the beginning and at the end of the study were analyzed for 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3.
RESULTS: Mean levels of 25-hydroxyvitamin D3 rose significantly by the same amount in both groups over the period of the study (placebo, +12.8 mmol/L; sunscreen, +11.8 mmol/L). (12.8 mmol/L = 5.12 nanograms/ml and 11.8 mil/L = 4.72 nanograms/ml )
Mean levels of 1,25-dihydroxyvitamin D3 increased significantly in the placebo group only (placebo, +10.8 pmol/L; sunscreen, +1.3 pmol/L), but for no subject in either group was the level of 1,25-dihydroxyvitamin D3 outside the reference range either at the start or at the end of the study.
There were no significant differences by age, sex, and skin type in the change in 25-hydroxyvitamin D3 or 1,25-dihydroxyvitamin D3 over the study period. http://www.medscape.com/medline/abstract/7726582