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  • High-Dose Vitamin D Does Not Lower Cataract Risk

    By Lynda Seminara
    Selected by Russell N. Van Gelder, MD, PhD
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    Journal Highlights

    Ophthalmology, March 2023

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    The presence of vitamin D receptors in the lens of the eye raises the possibility that high intake of this vitamin may influence cataract development. How­ever, findings of previous studies have been inconsistent, and randomized controlled trials are lacking. Rahman et al. conducted an ancillary study among participants of a nationwide Australian trial of the effects of vitamin D on all-cause mortality (the D-Health Trial) as well as recruited volunteers. Their goal was to determine whether high-dose vitamin D3 could reduce the incidence of cataract in older adults—and they found that it did not.

    The D-Health Trial was a seven-year, randomized, double-masked, placebo-controlled study of the Australian general population, which concluded in 2020. In that study, enrollees were as­signed randomly to receive 60,000 IU of vitamin D or placebo per month, each taken orally for up to five years. For this ancillary research, Rahman et al. invit­ed study participants and volunteers of similar age. They excluded people with hypercalcemia, hyperparathyroidism, kidney stones, osteomalacia, or sarcoid­osis, as well as anyone who was taking more than 500 IU per day of vitamin D. The primary outcome measure was the first surgery for cataract. Data were obtained from universal health insur­ance records and hospital data.

    Altogether, 19,925 individuals met the inclusion criteria. The par­ticipants’ mean age was 69.3 years (range, 60 to 84 years), and 46% were women. The rate of cataract surgery during follow-up (me­dian, five years) was 18.5% in the vitamin D group and 18.3% in the placebo group, and the incidence rates per 1,000 person years were 41.6 in the vitamin D group and 41.1 in the placebo group (hazard ratio, 1.02). Prespecified subgroup analyses by age, sex, body mass index, predict­ed serum level of 25(OH)D, and level of exposure to ambient UV radiation did not reveal significant differences between the study groups.

    In their discussion, the authors wrote, “although the results of the D-Health Trial are likely to be gen­eralizable broadly to the Australian setting and other communities with a similar prevalence of vitamin D deficiency, they are largely uninfor­mative about the effect on cataract of treating vitamin D deficiency or of population-wide supplementation in areas where a much higher proportion of people is vitamin D deficient.” As vitamin D deficiency has been linked to elevated inflammation and oxidative stress, supplementation may be helpful for conditions other than cataract, they acknowledged.

    The original article can be found here.