Vitamin D deficiency, which has been characterized by some researchers as reaching epidemic proportions, may compromise the effectiveness of osteoporosis therapy and contribute to the development of many nontraumatic fractures, according to reports at the annual meeting of The American Society of Bone and Mineral Research (ASBMR).

"Vitamin D inadequacy is an unrecognized epidemic, affecting all races and all age groups," Michael Holick, MD, professor of medicine at Boston University Medical Center said at the ASBMR in Seattle. "Despite the availability of over-the-counter multivitamins with vitamin D, people are still at risk for vitamin-D deficiency. To maximize effective osteoporosis therapy, a patient needs adequate calcium and vitamin D. The goal of osteoporosis therapy is to intervene early with bisphosphonates, but the drugs don't work as well if patients are vitamin D- or calcium-deficient."

In a study of more than 1900 women receiving treatment for osteoporosis, Dr. Holick reported that 52% demonstrated vitamin-D deficiency,¹ defined as a serum 25-hydroxyvitamin D (25-OHD) level of less than 30 ng/mL. Among women who received less than 400 IU of vitamin D daily, the prevalence of vitamin D inadequacy increased to 63%.

He cited two important factors that contribute to vitamin D deficiency and its role in poor bone health: the erroneous perception that vitamin D deficiency is associated only with rickets, and that excessive sunlight exposure, the body's principal source of vitamin D, may encourage people to reduce or eliminate much of their vitamin D consumption.

"Calcium and vitamin D are needed for osteoporosis drugs to work," Dr. Holick told CIAOMed. "If a patient is taking an osteoporosis drug and a calcium supplement without vitamin D, the patient will not get the full benefit of drug treatment."

A study presented by researchers at the University of Western Australia in Perth reinforced the importance of vitamin D supplementation to overall health and its contribution to preventing falls among elderly residents of nursing homes and assisted living facilities. In a randomized study involving 600 patients, the group taking vitamin D supplements had a 22% reduction in the risk of falling, and a 29% reduction among those who were at least 50% compliant with the supplementation,² reported Leon Flicker, MD.

"The results suggest that vitamin D might have an even greater benefit than just on bones and bone metabolism," Dr. Flicker told CIAOMed. "Vitamin D might be very helpful in keeping nerves and muscles working properly and thereby reduce the risk of falling."

The impact of vitamin D deficiency in an at-risk population was outlined by Christine Simonelli, MD, and colleagues at the HealthEast Medical Research Institute in St. Paul, Minn. In a study of 78 patients 50 years of age and older (61 of them women), who had been hospitalized for nontraumatic fracture, Dr. Simonelli reported that 97% also suffered from vitamin D deficiency.

The surprising finding, Dr. Simonelli told CIAOMed, was that the rates of calcium and vitamin D supplementation were low for such a high-risk population.

Overall, only 39 patients (50%) were receiving at least 400 IU of vitamin D or a multivitamin containing vitamin D, she noted, adding that only 27 patients (35%) were receiving calcium supplementation at a dose of at least 500 mg/day.

Vitamin D inadequacy was defined by 25-OHD cutoff points ranging between <9 ng/mL and <30 ng/mL. When employing the highest cutoff point, virtually all the patients were deficient in vitamin D, with a mean serum 25-OHD of 14.2 ng/mL. Specimens for assessment of 25-OHD were obtained within 48 hours of hospital admission.

References

1. Holick MF, et al.. J Bone Miner Metab.2004;19(suppl 1):S342.Abstract SU583.

2.Flicker L, et al. J Bone Miner Metab.2004;19(suppl 1):S99.Abstract F459 .