Research published in the Journal of Clinical Endocrinology & Metabolism reports that vitamin D deficiency is associated with frailty and all-cause mortality in older men.
The researchers, led by Yuen Wong, MBBS, were interested in examining the relationship between D deficiency, frailty and mortality in older men living in Australia.
The study included data from 4,200 men aged 70-88 years who were enrolled in the Health and Men cohort. This cohort began in 1996 and enrollees were followed through 2009. At baseline, the researchers looked at these men’s frailty scores and how and if they correlated with vitamin D levels at all. Frailty was assessed by the FRAIL scale which measures fatigue, resistance, ambulation, illness, and loss of weight. They also wanted to know if vitamin D levels and/or frailty were associated with mortality risk at all over the course of the 13 year study period.
Here’s what they found:
- Mean vitamin D status was 27 ng/ml.
- Participants with vitamin D levels greater than 48 ng/ml were younger in age and more likely to be physically active compared to men with levels < 48 ng/ml. The researchers did not mention how they chose 48 ng/ml as a cutoff here, though they did mention 65 men in the cohort had levels over 48 ng/ml and only 10 of these men supplemented.
- Men with levels < 20 ng/ml were twice as likely to be frail in comparison to those with levels > 32 ng/ml. Additionally, men who were non-frail at baseline with low vitamin D levels had a 50% increased risk of becoming frail within 5 years.
- Forty-eight percent of participants who were frail at baseline died during the study, while 23 % who were non-frail died. Men who died were also older, had more health complications, and had lower vitamin D levels than those who were living at the end of the study. The vitamin D status, mortality association only occurred at lower vitamin D levels (<20 ng/ml).
The authors conclude,
“…hypovitaminosis D is associated with prevalent frailty and predictive of incident frailty in older men. It is also predictive of all-cause mortality, independent of the baseline frailty status.”
While this isn’t the first study to examine vitamin D status, mortality, and frailty, it is interesting to see how the three relate to each other. The results suggest that vitamin D status predicts mortality independently of frailty.
The greatest limitation of the study was that participants were “self-selected,” which means they selected themselves to participate in the study. This could explain why vitamin D levels were higher than average, limiting the generalizability of the study results. Additionally, remember that although the study found a significant association, causality cannot be confirmed.
The authors call for large randomized controlled trials examining the effects of vitamin D supplementation on physical performance and frailty.