You’re probably familiar with Vitamin D as an important nutrient for bone health – but did you know that it may play a role in your athletic performance or recovery as a runner? Learn more about why Vitamin D is essential for runners, and how to get enough each day.
Disclaimer: This post was written and reviewed by Chrissy Carroll, MPH, RD, RRCA Certified Running Coach. It is for informational purposes only and should not be construed as medical advice. Always consult a doctor with any medical or supplement questions.
Functions of Vitamin D
Vitamin D is an essential nutrient, with two major established functions:
- Bone health – Vitamin D is necessary for the absorption of calcium from food, and helps to build and maintain strong bones (source).
- Immune system health – Vitamin D is involved in regulating both innate immunity (your body’s first response to an illness) as well as adaptive immunity (your body’s response specific to the type of illness it recognizes) (source). Several studies have linked Vitamin D deficiencies to increased risks of certain infections (source). Some scientists also believe that Vitamin D supplementation may help with vaccine efficacy in certain situations (source).
Clearly, both of these are important for runners. Good bone health is key for athletes, particularly those in a repetitive sport like running.
Indeed, research has found that low Vitamin D levels increase the risk of stress fractures in athletes, and that supplementation among those with low levels may decrease the prevalence of stress fractures. Similarly, a study of British army recruits found that those with lower Vitamin D levels took longer to recover from stress fractures.
And of course, a good immune support is essential for runners. When training for race, the last thing you probably want is to get sick and miss workouts. While adequate Vitamin D won’t necessarily prevent illnesses, it may help support your body’s response in fighting them.
Vitamin D and Running Performance
In addition the the functions above, there may be another role for Vitamin D in runners – and that’s athletic performance and recovery.
Let’s start with performance. Unfortunately, there are not many studies out right now that have evaluated running performance in relation to Vitamin D. However, there have been studies on other sports or other populations that may provide insight:
- 12 months of Vitamin D supplementation was associated with improved physical fitness markers among postmenopausal women, including relative strength, arm curls, and the 30 second chair stand (source).
- Supplementation and sun exposure in soccer players with insufficient Vitamin D levels led to improved blood levels and better 5 m sprints (source).
- Among college-aged males, Vitamin D supplementation was linked to improved maximal aerobic capacity (measured with cycling) and anaerobic power (also measured with cycling via a 30-second all-out sprint) (source).
Of course, not every study comes to the same conclusions. For example, among male professional football players, a study found no correlation between Vitamin D and muscle power or running speed. Another study found an 8 week supplementation regimen did not improve performance in well trained soccer players.
Vitamin D and Running Recovery
While performance studies are limited, there have been three very interesting studies specifically related to recovery from running:
- A single high dose Vitamin D supplement given 24 hours before an ultra marathon helped blunt the inflammatory response after exercise (source).
- 3 months of Vitamin D supplementation led to improved Vitamin D levels in healthy young men. After downhill running, those who had optimal Vitamin D levels were found to have lower levels of pro-inflammatory compounds and reduced muscle cell damage (source).
- 3 weeks of Vitamin D supplementation in ultra marathon runners led to higher blood levels of Vitamin D and decreased biomarkers of skeletal muscle damage – suggesting it possibly impacts recovery (source).
So while the role in performance may not be as clear, I do think the evidence is there supporting a role in recovery. And given that Vitamin D is so important for bone and immune health anyway – it’s smart for all runners to ensure they’re getting enough.
How much do you need?
The current RDA for Vitamin D is 600 IU for male and female adults age 19-70.
For adults over 70, this increases to 800 IU.
However, you may need more daily Vitamin D to raise your levels if you currently have insufficient levels (which are quite common).
In fact, research estimates around 40% of people have sub-optimal Vitamin D levels. And in a small study of collegiate runners, 95% did not meet daily Vitamin D recommendations.
You can ask your doctor to run a blood test to determine your Vitamin D levels and assess if they’re sufficient. The specific guidelines vary based on which organization you look to for guidance, but these are general cut offs according to the NIH:
- < 30 nmol/L (<12 ng/ml) – insufficient/deficient levels
- 30-50 nmol/L (12 to 20 ng/ml) – may be inadequate for optimal health
- > 50 nmol/L (>20 ng/ml) – adequate for optimal health
- >125 nmol/L (>50 ng/ml) – may have adverse effects from being too high
How to meet your Vitamin D requirements
There are three primary ways runners can meet vitamin D requirements (the last two of which I recommend more than the first):
1. Sunlight
Your body is able to make Vitamin D when sunlight hits exposed skin (without sunscreen). Research has shown people in areas with more sun exposure may have lower risks of Vitamin D deficiency.
For example – one study found fewer than 19% of female distance runners in the south had insufficient levels, meaning more than 81% had adequate levels. This is likely due to additional sun exposure compared to those who live in the north.
However, excess skin exposure to sunlight can increase the risk of skin cancer. Because of this, I recommend meeting your Vitamin D needs via the other two options.
2. Food sources
Unfortunately, few foods contain naturally high levels of vitamin D. But it’s still worthwhile to include a variety of sources in the diet to help meet your needs. The best sources in the diet include:
- Salmon
- Oysters
- Trout
- Irradiated mushrooms
- Egg yolks
- Fortified dairy and dairy alternatives
- Fortified cereals
- Fortified juices
3. Supplements
For many people, the best way of ensuring you are getting enough Vitamin D – especially if your levels are low – is taking a supplement.
Generally, a 1000 IU to 2000 IU supplement should meet most people’s needs. But always check with your doctor prior to beginning a supplement regimen to see what’s right for you. If your levels are very low, your doctor may recommend a limited-time high-dose supplement regimen to boost them, followed by a maintenance schedule on a lower dose.
The Bottom Line
Vitamin D is particularly important for runners, thanks to its involvement in bone health and immune health, along with potential impacts on athletic recovery and performance. Include Vitamin D-rich foods in your diet to help support your health and training. Talk to your doctor about getting your Vitamin D levels checked each year to determine if you have a deficiency, as well as to determine if a supplement is beneficial.
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