麻豆传媒

AUSTIN, Texas – Risk of COVID-19 infection didn't differ whether taking vitamin D supplements or having low levels of the vitamin, researchers reported here.

Among a cohort of 250 healthy healthcare workers, some of whom were taking high doses of vitamin D, 56 eventually tested positive for SARS-CoV-2 infection.

But there were no differences in infection rates stratified by vitamin D, comparing serum levels of 30 ng/mL or higher compared with less than 30 ng/mL, reported Yi Liu, MD, of the Hospital for Special Surgery in New York City.

In her oral presentation at the annual meeting of the American Society for Bone and Mineral Research, Liu noted there were some nonsignificant numerical differences between the groups that might have favored individuals taking supplements:

• 34% lower risk of SARS-CoV-2 infection with any vitamin D supplement use
• 59% lower risk if taking at least 2,000 IU of vitamin D daily
• 15% lower risk if taking at least 4,000 IU daily

However, the trend was in the other direction among those individuals who were constantly on supplements over the 15-month course of the study (HR 0.91, 95% CI 0.80-1.05).

The researchers also looked at subgroups by age, ethnicity, race, sex, and body mass index, along with vitamin D supplementation, and found no difference in the relationship between baseline serum vitamin D and infection with SARS-CoV-2.

When vaccines were available, all of the subjects were vaccinated, and 41 of those individuals had breakthrough infections. Again, Liu said, there were no statistically significant differences between those patients as far as vitamin D intake was concerned.

In commenting on the study, co-moderator Tiffany Kim, MD, of the University of California San Francisco, told 麻豆传媒, "While the study showed there was no value in taking vitamin D supplements to ward off COVID-19, there is still a question of whether supplementation with vitamin D would be worthwhile for people who were severely deficient in vitamin D and whether, in this group, the vitamin might be helpful."

"In the healthy population, there certainly is no reason to take high doses of vitamin D," she said.

The median baseline vitamin D level was 38 ng/mL, and "the majority of the subjects had vitamin D levels above the 30 ng/mL," Liu noted, agreeing with Kim.

She also noted that none of the individuals who had either symptomatic or asymptomatic COVID-19 developed severe disease that required hospitalization. For that reason, Liu said, her group was unable to evaluate how vitamin D levels could have had an impact on severe COVID-19 disease.

Liu said the researchers scrutinized whether vitamin D was helpful in warding off SARS-Co-2 infection due to conflicting reports of a possible benefit that have led some people to consume high levels of vitamin D.

"Based upon data linking vitamin D deficiency to risk of other respiratory infections, we hypothesized that individuals with lower 25-hydroxyvitamin D would have a higher incidence of infection with SARS-CoV-2," she said.

The healthcare workers studied were followed for 15 months from the spring of 2020 through the winter of 2022. The participants completed questionnaires every 3 months regarding new COVID-19 infections, vaccination, medical history, and supplement use.

Serum was drawn at baseline, 6, and 12 months for 25-hydroxyvitamin D and SARS-CoV-2 nucleocapsid antibodies. Incident infections were self-reported and confirmed by positive PCR or development of new nucleocapsid antibodies. Logistic regression was used to relate vitamin D status and supplement use to incident infection.

The mean age of participants was 40. Their mean body mass index was 26, 70% were Caucasian, and 77% were women.

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