Athletes are always looking for an edge in terms of their performance and dietary supplements have always been part and parcel of that search. And while most think of me as anti-supplement, that’s incorrect. I’m anti-bullshit. And most supplements are bullshit. That said, some are not and today I want to look at two specific supplements: Vitamin D and antioxidants in terms of how they might (or might not) help athletes. Specifically I will be looking at the following paper on the topic.
The Reality of Dietary Supplements
As I said above, I often get pegged as being anti-supplement but this is not true. I’m anti-bullshit. And having been in this field for over 2 decades, the simple fact is that I’ve seen hundreds of not thousands of products come and go. Of the total number, there are a handful that have stuck around with a few new compounds showing some potential benefit. But in the aggregate, it’s about 99% bullshit and 1% of “Well this might do something.”
Of course, that never stops athletes, who fall prey to the logic of “IF this is the next big thing, I don’t want to miss out on it.” Of course, supplement industries pander to that very thought process. That’s how they make shocking amounts of money off of desperate athletes.
I’m also anti-anything that takes away from the factors that actually matter. Training, diet, sleep, recovery, overall lifestyle, etc. All of these have a much more profound effect on an athlete’s results than any magic pill. Not unless that magic pill is an anabolic steroid. Those work great.
But at the end of the day, dietary supplements should be at the top of the pyramid in terms of the heirarchy of importance. For a high level athlete doing everything else right, they can occasionally add a little bit to the results. For anybody not at that level who doesn’t have the big factors, fixed, they aren’t relevant.
Antioxidants and Vitamin D
But I’m getting off topic. Today I only want to focus on two specific supplements. The first are the antioxidants, a class of supplements that has been popular and which is often recommended to hard training athletes. In short, these compounds help to scavenge what are called Reactive Oxygen Species (ROS) which are sometimes called free radicals.
These are produced under various conditions (including exercise) and one early theory of aging and bodily damage was that the production of ROS was part of the overall breaking down of the body. With the logical solution being to simply take these nutrients in doses ranging from reasonable to “Oh my god, you want me to take how much?” levels.
I can fondly remember Colgan and his laundry list of high-dose antioxidants in Optimum Sports Nutrition (an excellent book so long as you ignore every word about supplements) for example.
The other is Vitamin D which has been shown to do just about everything in everybody. Outside of a small percentage of folks, most are deficient. And correcting a deficiency does absolutely everything in terms of general health.
And it might even be specifically beneficial for athletes. This idea is actually not new and researchers in the early 20th century found that Ultraviolet (UV) light exposure improved athletic performance during the winter. In hindsight, this was probably due to improving Vitamin D status. Athletes who train near the equator where it’s sunny year round probably obtain benefits compared to those living in areas where winter dominates for half the year.
Which is all just a lead up to today’s paper, a relatively short review on both antioxidant and Vitamin D (and calcium) supplementation for athletes, looking at the role that they play in the body and arguments both for and against the use of either by athletes.
Antioxidants for Athletes
First let’s talk about the antioxidants. Like I said this is a class of compounds including such things as Vitamin A, Vitamin C, Vitamin E, beta-carotene and a little laundry list of others. Anytime you hear someone prattle on about a super food it’s usually due to the presence of either important phytonutrients or antioxidants within them.
As I also mentioned, these help to scavenge or help the body “deal with” ROS. These are produced within the body under a variety of conditions including exercise. It also appears that ROS production may be a cause of fatigue during exercise when they are produced in large quantities. This is in addition to potentially causing overall bodily damage through oxidative stress (also caused by such things as pollution and smoking) and muscle damage.
So logically, if ROS are produced during exercise and antioxidants help the body to deal with ROS, so went the logic that supplementing antioxidants would be beneficial for athletes. However, from a performance standpoint, they have almost always failed to improve performance.
The exception is N-Acetyl Cysteine (NAC) which appears to reduce fatigue during some types of submaximal exercise. It’s actually thought that this is due to NAC preventing fatigue in breathing muscles. Except for that, antioxidants have been ineffective.
Studies examining the impact of antioxidant supplementation on muscle and oxidative damage are pretty mixed. This probably reflects the difference in the type, amount and intensity of exercise along with the specific antioxidants and doses they were given at. Basically, outside of NAC and submaximal endurance performance, the data is far from conclusive.
Arguments for Antioxidant Supplementation in Athletes
The paper examines three potential reasons that athletes might consider antioxidant supplementation. First is the known increase in ROS production during activity, coupled with the general principle that antioxidant compounds are pretty much non-toxic even at relatively high levels. This is your basic “It probably won’t hurt and might help” kind of argument.
A second argument has to do with the role of excessive ROS on muscle fatigue. As I noted above, with the exception of NAC, most supplementation studies have shown no performance benefit of antioxidants so this argument pretty much fails.
Their final argument is the idea that many athletes have poor or insufficient diets (I’d note that most antioxidants come from fruits and vegetables). Thus these athletes may need supplementation to ensure adequate intake. I find this a pretty weak argument for reasons I don’t want to get into yet.
Arguments Against Antioxidant Supplements for Athletes
The paper also provides a number of arguments against antioxidant supplementation.
First they point out that while exercise certainly does increase ROS production it’s very transient. This distinguishes it from things like pollution or smoking which generate more chronic levels of ROS. As well, the body already has a built in antioxidant system to deal with ROS. Quite in fact, the bodies system increases it’s activity with training.
That is, by exposing the body to ROS in moderate amounts, it adapts by being better able to handle further ROS production Some have even theorized that high-dose antioxidant supplementation might be detrimental down the road by limiting the body’s need to improve it’s own built in system.
Even more damning, there is increasing amounts of evidence that the production of ROS is part of the stimulus to training adaptation, especially endurance training. That is, the production of ROS, like inflammation and a whole host of other things that occur with training appear to be part of the overall training stimulus. Blocking this with high-dose supplementation could conceivably limit the adaptations to training. I’d note that I was talking about this back in the mid 2000’s when the earliest research on this was starting to show up.
There is also the fact that isolated antioxidant supplementation doesn’t seem to have the same effects or benefits as diets that are high in antioxidants. Some has even suggested a HIGHER mortality rate from supplementation. Put differently, simply taking antioxidants in pill form isn’t the same (and can’t replace) eating foods high in antioxidant nutrients. This makes their third argument for supplementation invalid. Supplements can’t replace food.
The authors conclude that outside of ensuring a mixed, energy sufficient diet with plenty of fruits and vegetables (which should provide more than adequate natural antioxidants) there is no reason for athletes to supplement with individual high-dose antioxidants. Not only will it not help, it might actually hurt.
Vitamin D for Athletes
Next up is Vitamin D which the athletes choose to discuss along with calcium. Now Vitamin D is odd among the vitamins that the body can actually make it (in this sense it is a conditionally essential nutrient). This occurs in response to sun exposure where the skin actually produces Vitamin D in fairly large amounts. I won’t even attempt to give an overview of Vitamin D metabolism, go to Wikipedia or something.
Now Vitamin D is critical in the body for a number of reasons, not the least of which is bone health. In that vein, adequate Vitamin D status is required for optimal calcium absorption in the body. This makes adequate intake of both absolutely critical for women.
But Vitamin D does a million other things as well. It regulates gene expression, controls inflammation and immune system function and well, if you can name it, Vitamin D probably impacts it. A great deal of research has examined the relationship of Vitamin D status and colon cancer.
Of some relevance to athletes is that Vitamin D status is tied to muscular function. Vitamin D is also involved in the expression of a number of genes involved in strength and performance. These are all issues relevant to athletes.
Vitamin D and Seasonal Performance
As I mentioned above, there is a considerable history of evidence on the issue of Vitamin D and performance although it’s only in modern times that researchers have realized that Vitamin D was playing a role.
In the early part of the 20th century, researcher (German, of course) observed that athletes made less progress in strength and performance during the winter months. Logically, they thought, this might be due to reduced sun and Ultraviolet (UV) light exposure. So they exposed them to UV light and found that, voila, performance improved to the levels seen in the summer. But they didn’t know why or how.
We now clearly know that UVB exposure would have had one effect of increasing Vitamin D synthesis in the body and this may have been the mechanism improving athletic performance.
Vitamin D Deficiency is Epidemic
Of more relevance, recent research is finding that almost everyone is Vitamin D deficient, all over the world. This is due to a number of factors including the overuse of sunscreen, working indoors, a poor diet and others. Although the body can make Vitamin D, it also comes from the diet as does calcium. Many foods are fortified with both but that doesn’t mean that intake levels are anywhere near optimal.
This is due to a number of factors including things like overuse of sunscreen, working indoors, poor diet, etc. Both calcium and Vitamin D come from the diet (and many foods are fortified with both) but, as I mentioned, Vitamin D is an oddity among the vitamins in that it can be produced by the body, specifically in response to direct sun exposure.
So what is a good Vitamin D level. To be honest, there is still some debate on this point. The researchers provide the following values as a guide.
Now, as you might imagine, most of the work on Vitamin D status is not on athletes. But what work exists show that up to 90% of all athletes show insufficiency or outright deficiency levels of Vitamin D. This is especially true for athletes involved in indoor sports, or who train in areas with a harsh winter that limits sun exposure. While Vitamin D status will go up during the summer when athletes can train outside, those levels are only maintained for about a month or so without sufficient sun exposure or supplementation.
Even athletes who train in sunny areas may be at a risk for deficiency as the heat may cause them to train after sundown. It’s really only athletes who live in temperate year round sunny climates that are likely to not be at risk for Vitamin D deficiency. So athletes training at or near the equator probably.
Do Athletes Need Vitamin D Supplementation?
From that standpoint alone, supplementation is probably warranted for athletes who train indoors or who live in cold weather areas where sun exposure for a great part of the year simply isn’t available. A tanning bed might be another possibility.
Mind you, the direct data on Vitamin D and athletic performance isn’t major except for what I talked about above. But only a handful of studies have examined it. There does appear to be a positive correlation between Vitamin D status and things like strength and muscle force. This goes along with a decreased risk of stress fracture which is important for athletes in high-impact activities.
Mind you, claims such as “The higher the Vitamin D status the better your performance” are absolutely not supported by current research. Like so many things, benefits of Vitamin D supplements will come from correcting a frank deficiency. But bringing levels to optimal doesn’t ever mean that more is better.
The primary argument against Vitamin D supplementation is the overall lack of data indicating that performance is actually boosted. I would mention that performance per se is not always the proper end point. Given the role of Vitamin D in things like inflammation and immune system, ensuring optimal status would be critical to keep an athlete healthy. Simply, an athlete who is sick or injured (i.e. suffers a stress fracture) generally isn’t improving much. If Vitamin D helps with that, it’s having an indirect performance boosting effect.
In terms of arguments against supplementation, the main one is the overall lack of data indicating a performance boost; mind you that keeping an athlete healthy in general terms (and Vitamin D contributes to immune system function and bone health) is just as critical here. An injured or sick athlete isn’t training nor performing and the realities of Vitamin D deficiency should be addressed regardless of whether or not it improves performance.
How Much Vitamin D Do You need?
Vitamin D supplementation recommendations are weird with many official statements recommending a fairly low daily intake. And none of it makes any sense to me. Consider that 30 minutes or so of direct sun exposure will max out the body’s Vitamin D synthesis with roughly 10,000 IU’s being made. Logically we might consider this a maximum daily intake level. That is, it’s difficult for me to see how taking the same amount the body would make could be problematic.
However, others have set more conservative intake levels of perhaps 4000 IU’s per day. At the current time it’s not really known what level of supplementation might be toxic or dangerous.
The authors do note that there is individual difference in the absorption and utilization of Vitamin D. This could conceivably impact on how a given athlete responds to supplementation. Only blood work would be able to determine this reliably.
The authors recommend that, while there is little evidence that Vitamin D supplementation will improve performance (outside of correcting a deficiency), athletes should monitor their Vitamin D levels and supplement as needed.
For the most part what I wrote above doesn’t really differ to any significant degree from what I have written previously about dietary supplements for athletes.
In terms of antioxidant supplementation, I’m really not a fan under most circumstances. Not only do they not appear to have much if any benefit, especially taken in isolated form in high-doses, they may actually be detrimental to training adaptations. Using them during a primary training phase could slow adaptations.
However, they might have a role for athletes during a heavy competition schedule. Some studies do show decreased muscle soreness and damage and taking them during a heavy competition schedule might be worthwhile simply to keep the athlete in one piece. That’s in addition to NAC having a potential ergogenic benefit before certain types of endurance performance.
In terms of Vitamin D, outside of those athletes who can train consistently in the sun, I think supplementation is probably mandatory. Few athletes live in climates where outdoor sun exposure is available year round and the simple fact is that even if optimal levels occur during summer training, they only maintain about a month or so after the stimulus of regular sun exposure is removed.
Athletes who’s sports keep them indoors, or who live in areas with actual winter (where training is done indoors by choice or there is simply limited sun exposure) will find Vitamin D levels falling rapidly, potentially compromising immune system function, bone health and even trainability.
Supplementation will serve to maintain optimal Vitamin D status during those time periods.
And while it would be ideal for athletes to get regular blood work to determine levels along with their response to supplementation it’s not cheap work to do and has to be done at least twice. For athletes that can get it done, I’d mention that it takes, on average, 100 IU of Vitamin D to raise levels by 1 ng/mL. So an athlete with a Vitamin D level of 30 ng/mL who wants to get to 50 ng/mL would need 2000 IU’s per day.
As I noted above, 30 minutes of direct sun exposure generates 10,000 IU’s of Vitamin D and that appears to be the maximum the body will synthesize. A daily intake of half that should be more than safe and is in keeping with other maximum daily recommendations of 4000 IU/day.
And outside of extreme deficiencies, that level should cover most folks (that is if we assume levels drop to an insufficient 20-30 ng/mL during the winter, 5000 IU/day would be expected to raise that to 70-80 ng/mL right in the middle of the optimal range).
I’d note in closing that, as a fat soluble vitamin, Vitamin D should be taken with a fat containing meal for optimal absorption, Vitamin D is also a supplement that can be taken only weekly (i.e. 35,000 IU’s all at once or what they’d get from 5000 IU’s per day for a week) for athletes who are bad about taking pills.
- Dietary Supplements for Athletes
- Train Like an Athlete, Look Like an Athlete
- A Guide to Endurance Training Methods
- Dietary Protein Sources – Protein Quality Part 2
- Examining Some Dietary Protein Controversies