Is It Time To Rethink Vitamin D?
Vitamin D remains a very misunderstood vitamin. Epidemologic evidence has shown that Vitamin D deficiencies are correlated with a plethora of diseases ranging from osteoporosis to possibly even certain cancers; but studies have failed to show that supplementation provides much benefit. Which begs the question, is supplementation worth it?
What Is Vitamin D?
Vitamin D is a vitamin produced in your skin when you are exposed to moderate amounts of sunlight. Other sources of Vitamin D include certain foods like seafood and eggs, supplementation, and foods that have been fortified with Vitamin D.
Vitamin D has long been associated with increased bone health but more recent research appears to show that Vitamin D may have a role in numerous other functions throughout the body such as immune function and heart health among others.
What is Epidemiology?
Epidemiology is a branch of science that looks at factors that contribute to overall health and disease. Epidemiology studies typically look at large populations of people and observe characteristics that the groups of people share that may contribute to one being healthy or sick.
While epidemiology studies can be helpful in identifying certain risk factors or certain benefits, they can not show causation, only correlation. So, how does this apply to Vitamin D?
Observational studies have shown that lower than optimal Vitamin D levels are CORRELATED with many diseases ranging from metabolic disorders like diabetes, gum disease, and even certain cancers. Many of these studies show that people with higher levels of Vitamin D appear to have a lower prevalence of these disorders compared to those who have Vitamin D deficiencies.
Many contemporary health “gurus” use these studies as alleged proof that Vitamin D deficiency is a CAUSATIVE factor for these disorders, and therefore we must utilize supplements in order to be healthier. This is where it can get a little sticky. Remember that observational epidemiology can only show correlation and not causation. In other words, lower Vitamin D levels are correlated with adverse health outcomes, but are not necessarily causative of those outcomes.
If you want to do a deep dive on Vitamin D, here is a link to a paper from 2017 filled with some great information.
Improving Vitamin D levels May Improve Health, But Not If You’re Supplementing It.
This can seem a little confusing. If your Vitamin D levels are low and you start a regimen of Vitamin D supplements, your levels of Vitamin D will increase. However, this does not necessarily mean you will have improved outcomes resulting from these increased Vitamin D levels. Studies that look at health outcomes related to Vitamin D supplementation have shown very mixed results with some showing very weak potential benefits. Despite observational studies showing that higher Vitamin D levels are correlated with better health outcomes, studies that look at increasing levels through supplements show little positive effect.
How could that be?
First, we have to ask whether or not synthetic Vitamin D from supplements or fortified foods act in the same manner in your body as the Vitamin D you synthesize from sun exposure. The Vitamin D we obtain through pills and fortified foods is usually synthetic (meaning it is synthesized in a laboratory) and may not have the desired effect we hope to obtain.
Second, we must consider context when we look at healthy populations with higher Vitamin D levels. What do these populations typically have in common? In my opinion, this is where the rubber meets the road. Healthier populations with higher Vitamin D levels are typically more active and are therefore outdoors more often. Being outdoors more often will undoubtedly lead to higher Vitamin D levels. Being more active in general has been shown many times over to decrease many different chronic disease risk factors. We must ask ourselves, “are these populations healthier because of the increase in vitamin D, or are their improved health outcomes related to being more active?”
Putting This Into Action
If you live in a northern climate it may still be a good idea to supplement Vitamin D during winter months when we are unable to obtain it from sun exposure. However, supplementation should be based on recommendations from someone who is well versed in the current vitamin D guidelines.
The best overall recommendation regarding Vitamin D is to become as active as you can possibly be during the summer months when Vitamin D is available from the sun. We recommend playing pickle ball or moving down south :)
