Low vitamin D tied to lower risk of radiologic osteoarthritis in older men

A recent Korea study has found that low levels of vitamin D appear to be significantly protective against radiologic osteoarthritis (ROA) in older men but not women.

Drawing from the nationally representative Korea National Health and Nutrition Health Examination Survey, researchers assessed a total of 8,575 older adults (aged ≥50 years, 4,745 women) in whom vitamin D status was evaluated through fasting blood samples.

Less than half (47.7 percent; n=4,447) of participants had ROA, as determined through X-ray imaging of the lumbar spine, knee, and hip joints. ROA was also more common among women, with a prevalence of 54.5 percent, as opposed to its approximately 40-percent rate in men.

Logistic regression analysis found that participants with 25-hydroxyvitamin D levels <12 ng/mL were nearly 20-percent less likely to have ROA (odds ratio [OR], 0.81, 95 percent confidence interval [CI], 0.63–1.05), as compared with those with levels ≥20 ng/mL.

A similar effect was found for those with 25-hydroxyvitamin D concentration <20 ng/mL (OR, 0.83, 95 percent CI, 0.71–0.96; p_trend=0.03). Of note, this interaction was true for men only (p_trend=0.03).

“An unexpected positive association between vitamin D status and the odds of ROA was detected in Korean men. It is very unlikely that ROA increased vitamin D status,” the researchers said, pointing out that such an interaction is unlikely to be due to reverse causation. “On the other hand, further evaluation is required to test if vitamin D metabolites cause OA.

“Vitamin D may be involved in OA initiation but not progression in Korean men, but prospective studies are required to confirm causality,” they added.