February 25, 2013

205 Calcium, Vitamin D & Fractures [25 February 2013]

Last week we looked at certain built-in bias that favors drugs being tested. I have previously discussed how studies and/or their news reports can be slanted to discredit natural health products (#112 A Sabotaged Cancer Study, #176 Nutrition in the News). In August 2012 (#177 Preventing Fractures) I reported on a critique of the 2012 USPSTF meta-analysis study which concluded that calcium and vitamin D supplementation at RDA levels provided no benefit and were best avoided due to slightly increased risk of kidney stones. Among the noted flaws were the low dosage of vitamin D; the poorly-absorbed form of calcium used; and missing cofactors for bone formation including magnesium, vitamin K2, and various trace minerals. A similar study with similar conclusions was recently re-analyzed leading to a completely different conclusion.

The Women’s Health Initiative (WHI), a large controlled study of more than 36,000 post-menopausal women over 7 years, examined the effects of supplementation with 1000mg calcium and 400iu vitamin D on bone density and fractures. The original analysis, published in the New England J. of Medicine in 2006, concluded that the supplementation provided no significant reduction in hip fractures and only a small improvement in bone density.

A recent re-analysis of the WHI data by Dr. Ross Prentice and colleagues from the Fred Hutchinson Research Center in Seattle, published in Osteoporosis International 24(2) in February 2013, came up with a different conclusion. The authors found that the original analysis didn’t account for women who were taking supplements prior to the study and for women who quit partway through. After adjusting for these data, the researchers found significant reductions of fracture risk: 29% and 38%. They concluded “…long-term use of calcium and vitamin D appears to confer a reduction that may be substantial in the risk of hip fracture among postmenopausal women”. Just imagine the benefits they might have found had they used optimum supplementation levels and included all the co-factors!

For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner.

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