The Role of Vitamin D in Running Performance

Vitamin D is often called the "sunshine vitamin," but my interest in Vitamin D goes beyond the usual concerns of winter and northern climates. As an avid treadmill runner, I don’t spend as much time outside as many other runners, which means I might not get as much natural Vitamin D exposure. And living in Atlanta, I tend to avoid the intense summer heat, further limiting my sun exposure.

For runners , maintaining optimal Vitamin D levels is critical for performance, recovery, and overall well-being. Let’s explore why Vitamin D matters for runners and how to ensure you’re getting enough.

Why Vitamin D Matters for Runners

Vitamin D is essential for runners because it impacts multiple physiological systems that contribute to performance and recovery. From bone strength to immune support, maintaining adequate Vitamin D levels helps ensure that the body can withstand the demands of endurance training. Research published in JAMA highlights the role of Vitamin D in muscle function and injury prevention, reinforcing its importance for athletes. Research published in JAMA highlights the role of Vitamin D in muscle function and injury prevention, reinforcing its importance for athletes.

Vitamin D is essential for runners because it impacts multiple physiological systems that contribute to performance and recovery. From bone strength to immune support, maintaining adequate Vitamin D levels helps ensure that the body can withstand the demands of endurance training.

• Bone Health & Injury Prevention – Running is a high-impact sport, and bone density is crucial for preventing stress fractures and injuries. Vitamin D plays a key role in calcium absorption, ensuring strong bones and reducing the risk of injury. A study from the National Institutes of Health (NIH) confirms that Vitamin D deficiency is linked to an increased risk of stress fractures in endurance athletes.
• Muscle Function & Strength – Studies show that athletes with adequate Vitamin D levels demonstrate better muscle function, power output, and endurance. Low levels have been linked to muscle weakness and fatigue, which can impact both training and race-day performance.
• Energy & Recovery – Vitamin D supports mitochondrial function, ensuring efficient energy use and faster muscle repair. Deficiency in Vitamin D has been associated with chronic fatigue and longer recovery times after workouts. According to Harvard Medical School, Vitamin D plays a crucial role in reducing inflammation and promoting muscle recovery after intense training sessions.

Seasonal and Latitudinal Challenges in Vitamin D Synthesis

Where you live and train plays a significant role in how much Vitamin D your body can naturally produce. Sunlight exposure varies by season and latitude, which means some runners are at higher risk of deficiency than others. According to a Harvard Health article, individuals in northern climates are particularly susceptible to Vitamin D deficiency during winter months, which can negatively affect energy levels and recovery.

Where you live and train plays a significant role in how much Vitamin D your body can naturally produce. Sunlight exposure varies by season and latitude, which means some runners are at higher risk of deficiency than others.

• Reduced Sunlight in Winter – During fall and winter, the sun's rays are less direct, reducing the skin's ability to synthesize Vitamin D.
• Latitude Matters – Research indicates that individuals residing above approximately 37 degrees north latitude—roughly the line connecting San Francisco to Philadelphia—cannot produce adequate Vitamin D from sunlight between November and February due to the sun's lower angle.
• Athlete Risk – A meta-analysis of 23 studies involving over 2,000 athletes found that nearly 56% had insufficient Vitamin D levels, which can adversely affect health and training efficiency (Runner's World).

Dosage: How Much Vitamin D Do Runners Need?

Finding the right Vitamin D intake depends on various factors, including training volume, sun exposure, and individual body needs. While general guidelines exist, runners who train mostly indoors or live in low-sunlight areas may require higher doses to maintain optimal levels. A study in the American Journal of Clinical Nutrition found that higher Vitamin D levels are linked to improved muscle efficiency and faster recovery in endurance athletes.

Finding the right Vitamin D intake depends on various factors, including training volume, sun exposure, and individual body needs. While general guidelines exist, runners who train mostly indoors or live in low-sunlight areas may require higher doses to maintain optimal levels.?

• 600-800 IU per day (15-20mcg) is the general recommendation for most adults.
• Optimal Blood Levels – A range of 30-50 ng/mL is generally considered ideal for performance and health.
• Avoiding Toxicity – Excessive Vitamin D can lead to toxicity, so runners should check their levels with a healthcare provider before supplementing beyond recommended amounts.

Vitamin D supplementation can be complex. Peregrune Runner Multivitamin contains 6.7 mcg per daily dose, which is lower than the general recommendation of 600-800 IU per day. However, most adults already obtain Vitamin D from their diets, as many foods in the U.S. are fortified with it due to its essential role in health. Because of this, a full daily dose from a multivitamin is often unnecessary unless a physician recommends it based on blood work. 

How Vitamin D Supplements Are Made

Understanding how Vitamin D supplements are produced can help runners make informed decisions about what they are putting into their bodies. Since Vitamin D is not naturally abundant in many foods, supplementing is often necessary, and there are key differences between non-vegan and vegan sources.

As a chemist, engineer, and runner, I am always interested in how Vitamin D supplements are made. Vitamin D is unique because it made by humans when skin is radiated with UV light from the sun. Synthetic Vitamin D comes in non-vegan and vegan varieties. 

• Vitamin D3 – Traditionally sourced from lanolin, a substance extracted from sheep’s wool. Lanolin is exposed to UV, creating Vitamin D. Lanolin is a naturally occurring wax found in sheep’s wool. To extract Vitamin D, raw wool is first cleaned and processed to isolate lanolin, which is then refined into a pure fat. This fat is exposed to ultraviolet (UV) light, mimicking the natural process that occurs in human skin when exposed to sunlight. The UV exposure triggers a photochemical reaction, converting the lanolin into 7-dehydrocholesterol, which then transforms into cholecalciferol (Vitamin D3). After this conversion, the resulting Vitamin D3 is purified, stabilized, and used in supplements. This method ensures a high-potency, bioavailable form of Vitamin D3 while maintaining the integrity of the nutrient.
• Vegan Vitamin D3 – Derived from lichen, making it a great option for those avoiding animal products. This is the form used in Peregrune’s Runner Multivitamin
• Vitamin D2 (Ergocalciferol) – Sourced from fungi, such as mushrooms exposed to UV light. Less bioavailable than D3.

How to Optimize Your Vitamin D Levels

Maintaining sufficient Vitamin D levels requires a combination of lifestyle choices, dietary adjustments, and supplementation when needed. Runners who struggle with sun exposure or diet alone may need to take additional steps to ensure their levels remain adequate year-round.

• Get More Sunlight – Aim for 15-30 minutes of direct sunlight per day depending on skin type and location.
• Eat Vitamin D-Rich Foods – Include fatty fish, eggs, and fortified dairy products in your diet.
• Supplement When Needed – Many runners struggle to get enough Vitamin D from food and sunlight alone, especially in winter. Peregrune’s Runner Multivitamin provides Vitamin D in amounts specifically tailored for endurance athletes (Peregrune Vitamin D and Running Performance).

Final Thoughts

Vitamin D plays a critical role in running performance, recovery, and overall health. Ensuring adequate levels can help reduce injury risk, improve muscle function, and support immune health. If you’re not getting enough through sunlight and diet, supplementation can be an effective way to stay strong and healthy year-round.

For more insights on running nutrition, check out our Peregrune Blog.