Vitamin D Linked With Neuromuscular Performance in the Elderly

Linda Little

September 28, 2005

Sept. 28, 2005 (Nashville) — Low serum levels of vitamin D in the body may make elderly persons more susceptible to falls, Netherlands researchers reported here at the American Society of Mineral and Bone Research (ASBMR) 27th annual meeting.

"Low levels of vitamin D were associated with low physical performance," said Ilse Wicherts, a doctorate student at Vu University Medical Center in Amsterdam, the Netherlands. "This study shows that neuromuscular performance in those with lower levels of vitamin D was significantly lower than those with adequate levels.

"These individuals already are fragile," added Ms. Wicherts, the winner of an ASMBR Young Investigator Award. "The lack of mobility places them at high risk of falls and fractures."

In the study 1,238 men and women (mean age, 75 years) by Ms. Wicherts and colleagues, a low serum level of vitamin D was associated with lower neuromuscular performance. The study was undertaken within the framework of the Longitudinal Aging Study Amsterdam (LASA).

Neuromuscular performance was measured by five chair stands for muscle strength, a walking test for balance, and tandem stand testing coordination and mobility where participants must stand with one foot in front of the other. Each performance test was scored in seconds and was classified with scores from 1 to 4 according to quartiles of distribution. The total performance score for muscle strength and balance ranged from 0 to 12. The researchers used a multivariate regression analysis adjusted for age, sex, and body mass index.

Eleven percent of the participants had serum vitamin D levels less than 25 nmol/L, 37% had levels between 25 and 50 nmol/L, 33% had levels between 50 and 75 nmol/L, and 17% had levels of 75 nmol/L or above.

Scores for chair stands, the walking test, and tandem stand each showed significant improvement with increased serum levels of vitamin D.

Participants with vitamin D at 25 nmol/L had a performance score of 4.9 while those with vitamin D levels between 25 and 50 nmol/L had scores of 6.82 and those with levels between 50 and 75 nmol/L had scores of 8.10. Participants with vitamin D levels of 75 nmol/L or higher had performance scores of 8.72.

"There was a linear progression," Ms. Wicherts said. "The change in performance scores with increasing serum 25(OH)D was significant for all steps."

When researchers adjusted for age, sex, body mass index, smoking, and alcohol consumption, the performance score increased significantly with serum vitamin D levels up to 50 nmol/L. Performance was reduced 18% if the vitamin D levels were lower than 25 nmol/L compared with participants with levels of 75 nmol/L or higher and 5% if vitamin D levels were between 25 and 50 nmol/L after adjusting for other risk factors, Ms. Wicherts said.

"Persons with low serum vitamin D levels had a higher risk for low physical performance," Ms. Wiecherts told Medscape. "The strongest effects were found in persons with a major deficiency."

"This is a very important study because it suggests that vitamin D is not only important for bone health, but is important in neuromuscular stability," said Elizabeth Shane, MD, president-elect of ASBMR. "Bone fracture is due to not only bone issues, but issues contributing to falls.

"There is a two-pronged effect here that can increase the propensity for fractures in the elderly," Dr. Shane said. "Adequate Vitamin D can aid in improving muscle strength and preventing falls in this older age group."

ASBMR 27th Annual Meeting: Abstract 1134. Presented September 26, 2005.

Reviewed by Gary D. Vogin, MD

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