Vitamin D reduces need for antibiotics in seniors, according to new trial

Posted on October 15, 2013 by Brant Cebulla

A new randomized controlled trial out of Australia suggests that vitamin D reduces the need for antibiotics.
Research to date on vitamin D’s role in the immune system and fighting infection has primarily focused on viral infections. A few small trials have found a reduction in influenza incidence and a reduction in general upper respiratory tract infections for those who took vitamin D compared to those who took placebo.
For bacterial infections, there have been a few trails looking at vitamin D’s effect on tuberculosis, with mixed results. There have also been a few trials looking at vitamin D’s effect on the need for antibiotic use, but the trials have been few and small, although they have shown some promising results.
In the present study, researchers wanted to fill this gap in research and examine vitamin D’s effect on the need for antibiotic use. They wanted to know, if people take vitamin D supplements, does it reduce their need for antibiotics? If yes, this would suggest that vitamin D does have a hand in fighting bacterial infections.
Researchers enrolled 644 people into their study. They randomly assigned one-third of them to take a placebo pill, one-third to take 30,000 IU and one-third to take 60,000 IU once per month for a year.
The researchers measured vitamin D levels at baseline and at the end of study. They kept track of antibiotic use by using Australia’s national administrative health data, so the participants didn’t have to self-report.
At the end of the trial, here is what they found:

• Seventy-five percent of patients were deficient in vitamin D at baseline (level under 20 ng/ml). Mean vitamin D levels in the 30,000 IU group increased from 16.8 ng/ml at baseline to 25.6 ng/ml over the year. Mean vitamin D levels in the 60,000 IU group increased from 16.8 ng/ml at baseline to 31.2 ng/ml. Placebo levels remained the same, with a level around 17 ng/ml.
• People in the 60,000 IU group had a nonsignificant lower risk of having at least one antibiotic prescribed compared to people taking placebo (RR: 0.72; 95% CI: 0.48, 1.07; P = 0.10). The 30,000 IU group also had a nonsignificant lower risk of having at least one antibiotic prescribed, although the association was even weaker (RR: 0.84; 95% CI: 0.57, 1.25; P = 0.40), which makes sense since it was a lower dose.
• When the researchers stratified their results based on age and only looked at seniors over 70 years old, they observed a significantly lower risk of having at least one antibiotic prescribed compared to people taking placebo (RR: 0.53; 95% CI: 0.32, 0.90; P = 0.02). They could not find a statistically significant relationship for younger age brackets.

The researchers concluded,
“Our results lend some support to the hypothesis that vitamin D supplementation might reduce the need for antibiotics, particularly in people aged over 70 years old. Because this was a post hoc analysis and quite possibly because of chance, the results suggest that future trials of vitamin D with antibiotic use or common infections as key outcomes are warranted.”
Prior to looking at the data, the researchers hypothesized that vitamin D would be most beneficial to seniors because of the known progressive decline of immune function as you age. And that’s exactly what they found: vitamin D was of almost exclusive benefit to seniors in protecting against need for antibiotics.
Future research should examine this topic using a larger dose of vitamin D and if possible, a larger population, to try and elucidate the antibiotic effects of vitamin D across all age groups.
Source
Tran B et al. Effect of vitamin D supplementation on antibiotic use; a randomized controlled trial. AJCN, 2013