Fast Five Quiz: Vitamin D Practice Essentials

Romesh Khardori, MD, PhD


February 09, 2022

A recent randomized trial that included nearly 26,000 adults found that 5 years of vitamin D supplementation was associated with a 22% reduction in risk for confirmed autoimmune diseases. The study included 12,786 men aged 50 years or older and 13,085 women aged 55 years or older. Confirmed incident autoimmune diseases occurred in 123 patients in the active vitamin D group after 5 years compared with 155 in the placebo vitamin D group, translating into a hazard ratio of 0.78 for vitamin D (P = .045).

In a randomized trial of more than 1000 patients, daily supplementation of vitamin D and calcium carbonate was found to significantly reduce recurrence of benign paroxysmal positional vertigo (BPPV). The optimal dose and duration of supplementation to prevent BPPV remains uncertain, as does the target serum vitamin D level. Participants were divided into intervention and observation groups. The number of recurrences per 1 person year was 0.83 in the intervention group and 1.10 in the observation group. This yielded an incidence rate ratio of 0.76 and a reduction in the annual recurrence rate of 0.27 in the group that received with supplementation.

An observational study found that women who consume higher levels of vitamin D — particularly from dietary sources — have a reduced risk for early-onset colorectal cancer. The study included 94,205 women (aged 25-42 years) who were followed between 1991 and 2015. Women who consumed the highest average total vitamin D (450 IU/d) demonstrated significantly reduced risk compared with those consuming < 300 IU/d.

A separate prospective, population-based study of men found that lower concentrations of vitamin D were associated with increased all-cause mortality. The research concluded that assessment of free 25-hydroxyvitamin D (25[OH]D) offers little added benefit to the current standard of total 25(OH)D, the major circulating form of vitamin D, because deficiencies in each are associated with a similar risk. The men were between 40 and 79 years of age and had a mean follow-up of 12.3 years. During that time, about a quarter (23.5%) of them died. After adjustment for key confounders, including body mass index, smoking, alcohol consumption, kidney function, number of comorbidities at baseline, and other factors, men with a total 25(OH)D level < 20 µg/L had a significantly increased risk for mortality compared with those who had normal levels of vitamin D, defined as > 30 µg/L (hazard ratio, 2.03; P < .001).

Learn more about vitamin D supplementation.


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