Let’s rewind the clock about 20 years to 1998.
This year sticks out in my mind for one major reason: Harry Potter had to find the Sorcerer’s Stone which made the Elixir of Life.
This Elixir had the ability to grant the drinker eternal life and also cure all diseases.
Voldemort strangely occupied the back of some dude’s head (still haven’t figured that one out) and convinced him to try and steal this stone so he could come back to life.
Harry thwarted him and that stone got destroyed.
What the heck does that have to do with vitamin D? Well, in many ways, the fervor that has been generated around vitamin D makes it seem like it might be the true Elixir of Life.
For about 5 years there was a mind-blowing boom of articles and small companies trying to capitalize on the interest in vitamin D.
While many of the claims about vitamin D are hyperbole, there are some very interesting aspects of vitamin D that are worth exploring and most of them deal with correcting deficiencies.
Vitamin D and Athletic Performance
There has been a substantial amount of pomp and circumstance surrounding vitamin D as an ergogenic aid and claims have circulated that taking large amounts of vitamin D can enhance your performance in the gym.
Related: The Absolute Beginner's Guide to Bodybuilding Supplements
This question was so pervasive and so interesting that we actually conducted a rigorous analysis of the current scientific literature and wrote a peer-reviewed paper on the topic1.
There have been several studies that have examined levels of vitamin D and aerobic performance. What we can tell from the scientific data is that people who have low levels of vitamin D appear to have lower aerobic capacity than people with adequate levels of vitamin D.
Additionally, it is very likely that supplementing with vitamin D to correct a vitamin D deficiency might provide a small benefit on aerobic performance.
There has also been some interest in recovery. Most of the evidence has been done in cells and rats, but one study showed a very small improvement in loss of power output.
However, it was only one study with a small number, so we can’t say anything for sure but I would argue supplementing vitamin D to correct a deficiency would be helpful to optimize recovery.
There is also some speculation that large doses of vitamin D improves power production and force output.
A few small studies seem to suggest this might be possible but the effects are quite small and other studies show no response. I think we can safely conclude that a vitamin D pre-workout supplement is pretty much dead on arrival and not worth much investigation from a maximal effort standpoint.
Vitamin D and Infections
Vitamin D may be a critical piece to warding off infection. No, not as an anti-zombie spray. Vitamin D actually plays a regulatory role in your immune system and supplementation with vitamin D has been shown to be helpful in preventing respiratory infections.
In a recent study that examined 25 studies, researchers showed that supplementation of vitamin D substantially reduces your risk of acquiring acute respiratory tract infections2.
However, there is a little caveat to it. It really only makes a meaningful difference if you are deficient in vitamin D, people who had normal levels only had a very small reduction in risk of acquiring an infection. Also, small, daily or weekly doses were much better than infrequent large doses.
Vitamin D and Fat Loss
For some very strange, borderline asinine reason someone, somewhere along the way took some preliminary research and decided they would make some claims that vitamin D is a good supplement for fat loss.
Um, no. This is not true.
It is true that vitamin D deficiency can cause a lot of issues with hormones, calcium regulation, mood, immune function, and a lot of other processes, but there is no evidence to suggest that has any meaningful effect on fat loss.
For people who are “dieting” or restricting calories supplementing with vitamin D to ensure they are getting enough vitamin D to maintain their vitamin D levels is an awesome idea. It just won’t turn you into a fat burning furnace.
Your Vitamin D Levels are Probably Low
I know what you are thinking, “I don’t need to worry about this; I am healthy so I am good”. Well, it turns out you probably do need to think about your vitamin D levels. 41% of adults in the United States are vitamin D deficient3. That means 4 out of 10 people don’t have enough vitamin D and really need to consider supplementing with it.
Related: Supplementing for Success - The Key Mineral You're Deficient In
Why is there such a large percentage of people with vitamin D deficiency? Well, your blood levels of vitamin D are determined by your genetics, diet, and sun exposure.
Most of us get a tiny fraction of the sunlight we actually need due to the amount of time we spend indoors. For those of us who live in the northern part of North America we also get much less intense solar radiation and for what seems to be 11 months out of the year almost zero sunny days.
Also, most of us do not eat diets rich in vitamin D. Combine these things together and you get the perfect storm to ensure that large amounts of people are vitamin D deficient.
What Kind and How Much Should I Take?
Supplementing with vitamin D is actually fairly simple for most of us.
If you have levels below 20 ng/mL you should be supplementing with between 1,000 IU and 5,000 IU a day until you reach normal levels. You should be taking vitamin D3, not vitamin D2.
You can take it as a daily vitamin, usually with a meal as vitamin D is fat soluble.
The Wrap Up
Chances are your vitamin D levels are low and should be getting them checked at your annual checkup with your doctor (you definitely should be getting an annual checkup).
There is some evidence that letting your vitamin D levels stay low increases your risks of infections, reduces your overall aerobic performance, and might limit your recovery.
If you want to stay at the top of your game, correct any deficiency that you might have with smart vitamin D supplementation, especially during the winter months. If they are low you should supplement with around 1000-5000 IU of vitamin D3 per day until your levels are back in normal range.
Too much Vitamin D can cause problems with calcium levels.