Study Identifies “Reassuring” Vitamin D Levels for Health in the Elderly
By Greg Arnold, DC, CSCS, May 16, 2012, abstracted from “Serum 25-Hydroxyvitamin D Concentration and Risk for Major Clinical Disease Events in a Community-Based Population of Older Adults” in the May 1, 2012 issue of the Annals of Internal Medicine
The past several years has produced research showing vitamin D to play a role far beyond helping to absorb calcium and strengthen bones. It also has been found to decrease the risk of heart disease, cancer, and all-cause mortality (1,2,3,4). While the Institute of Medicine recommends at least 50 nanomoles/Liter (20 nanograms/milliliter) for optimal health (5), other professional societies and expert panels recommend at least 75-nmol/L (30-ng/mL) (6, 7, 8, 9).
Now a new study (10) has strengthened the Institute of Medicine’s vitamin D recommendations in the elderly. In the study, researchers analyzed the vitamin D levels of 1,621 Caucasian adults older than 65 participating in The Cardiovascular Health Study (21). They analyzed their vitamin D levels in 1992 and then followed the patients’ records for an average of 11 years, looking for any evidence of hip fracture, heart attack, cancer, or death from any cause.
During the 11 years of follow-up, the researchers found a seasonal variation threshold for vitamin D relating to sun exposure corresponding to increased risks of illness in winter (45 nmol/L (18 ng/mL)), spring (52 nmol/L (21 ng/mL)), summer (63 nmol/L (24 ng/mL)), and fall (57 nmol/L, 23 ng/mL)). Specifically, those with the lowest 30% of vitamin D blood levels during any particular season had a 24% increased overall incidence of adverse events listed in the paragraph above compared to those with the highest 30% of vitamin D levels for that specific season.
With the combination of no seasonal variations reaching 75 nmol/L but instead revolving much more around 50 nmol/L and benefits of having levels higher than 50 nmol/L, the researchers felt the 50 nmol/L (20 ng/mL) threshold to be “reassuring” and concluded that “we found ‘optimal’ concentrations of [vitamin D blood levels]…centered near 50 nmol/L (20 ng/mL) and that season-specific targets for [vitamin D] concentration are more appropriate than static targets when considering potential implications for long-term health.” An analysis of the benefits at higher levels was not done according to the authors, “A threshold as high as 75nmol/L (30ng/mL) was unlikely to be congruent with our data.”
Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY. You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com
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