We are still working to figure out why low levels of vitamin D are associated with worse outcomes in critical illness, noted Todd W. Rice, MD, FCCP, associate professor of medicine at Vanderbilt University Medical Center in Nashville, Tennessee.
Studies have shown that low levels of vitamin D are associated with worse outcomes in critical illness—for instance, needing to be in the intensive care unit (ICU) more—but we are still working to figure out why, noted Todd W. Rice, MD, FCCP, associate professor of medicine at Vanderbilt University Medical Center in Nashville, Tennessee, in an interview for this year’s CHEST Annual Meeting.
Tell us about your presentation on day 1 of CHEST, “Vitamin D in Critical Illness: Helpful Fact or Hopeless Fiction.”
This is a presentation in a session about vitamins and vitamins in the ICU. And obviously, based off of the title, I’m going to talk about vitamin D. The short, brief story of vitamin D is that we’ve had a number of studies that have shown that low levels of vitamin D are associated with worse outcomes, including needing to be into the ICU more, having more infections in the ICU, and staying in the ICU longer, having higher mortality while you’re in the ICU. And so the thought process is that repleting people’s vitamin D to normal levels may prevent some of these bad outcomes. And we’ve tried this in a number of trials and we haven’t had great success in improving outcomes by giving patients vitamin D. And the question then becomes, why is that the case? Is it that low vitamin D level is not the reason that people do worse, it’s just kind of associated with being sick and doing worse? Or is there something about vitamin D metabolism and vitamin D absorption that we don’t yet understand? So we’re not really supplementing it right, we’re not really targeting the right levels, those sorts of things. And I think we’re still working to figure that out.
How do the pleiotropic effects of micronutrients affect critical illness?
Vitamin D has a number of kind of positive effects in the body. Obviously, it’s involved in bone metabolism—that’s probably not that relevant in critical illness—but it’s very, very, very much involved in the immune system. And it’s sort of a cofactor for our immune cells in fighting infection. And it’s been shown in a number of other studies, not in the ICU, that low vitamin D levels result in less robust immune systems, more prone to get infections, and worse outcomes.
The other effects of it are that it seems to have some anti-inflammatory effects. We don’t entirely understand exactly how it decreases inflammation, but it seems to decrease inflammation and also kind of has some effects on the endothelial lining of the lungs and the vasculature. So all of those effects kind of together are pleiotropic in the fact that they sort of grow these areas, stimulate these areas, and are beneficial to the body in that regard.