According to a new Austrian study, low vitamin D levels, common among women in nursing homes, may raise their mortality risk.
In the observational study vitamin D concentrations in blood samples of 961 relatively healthy and mobile women aged 70 and above (mean 84) living at 95 nursing homes in Austria were examined and cases of death were registered over 27 months (1). The study results showed that the participants with the lowest vitamin D levels, averaging less than 14 nmol/L vitamin D, were 49% more likely to die than those with the highest levels (more than 25.5 nmol/L). After adjustment for age, body mass index, glucose control, heart disease status, mobility status, and other factors, mortality risk associated with the lowest vitamin D levels was still 56% greater than for the highest levels. Only 7% of the female nursing home population had adequate levels of at least 50 nmol/L when tested during winter in Austria, which is at a similar latitude as Montreal. Blood samples collected in February and March pointed to a median serum 25-hydroxyvitamin D of only 17.5 nmol/L.
The researchers concluded that these findings underscored the urgent need for effective strategies for the prevention and treatment of vitamin D deficiency, in particular, in the setting of nursing homes. Preemptive vitamin D supplementation of at least 800 IU per day would be reasonable, even without vitamin D testing, for elderly nursing home residents with limited access to sunlight, nutritional deficits and impaired synthesis of vitamin D in aging skin. Having had an adequate reference group that averaged at least sufficient vitamin D levels might have led to more significant associations between vitamin D and mortality, the scientists noted. One limitation was the difficulty of differentiating between possible confounding factors and parame-ters of the causal chain of vitamin D deficiency, because the vitamin has a role in so many disease-related processes.