One nutrient that plays a pivotal role in optimising health and athletic performance is Vitamin D. Vitamin D is a fat-soluble vitamin that is unique in that it can be synthesised by the body when the skin is exposed to sunlight. It also occurs naturally in certain foods and can be obtained through supplements. The two most important forms of Vitamin D are Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol). While Vitamin D2 is primarily found in plant-based sources, Vitamin D3 is the form that is synthesised by the skin and is also available in some animal-based foods and supplements.
The Importance of Vitamin D in Health and Performance
Maintaining strong and healthy bones is essential for athletes, as they constantly subject their skeletal system to stress and impact during training and competition. Vitamin D plays a crucial role in this aspect by facilitating the absorption of calcium and phosphorus from the diet. These minerals are fundamental for the development and maintenance of bone density and strength. Inadequate Vitamin D levels can lead to a decreased ability to absorb calcium efficiently, which may result in weakened bones and an increased risk of stress fractures.
A study published in the Journal of Bone and Mineral Research in 2018  reported that Vitamin D supplementation significantly improved bone mineral density and reduced the risk of stress fractures in female military personnel. This emphasises the direct link between Vitamin D and bone health, particularly in physically active individuals.
Immune System Support
For individuals, especially athletes, maintaining a robust immune system is crucial, as illnesses or infections can derail training schedules and performance goals. Emerging research suggests that Vitamin D plays a pivotal role in immune system modulation. It helps regulate immune responses, making the body more effective at defending against pathogens. Adequate Vitamin D levels may reduce the risk of upper respiratory tract infections, which are common among athletes due to intense training and exposure to various environments.
A study published in Nutrients in 2020  highlighted the relationship between Vitamin D and immune function. It proposed that optimising Vitamin D levels may contribute to a decreased risk of infections in athletes.
Efficient muscle function is a cornerstone of athletic performance. Vitamin D is believed to play a role in muscle health by influencing muscle strength and function. Insufficient Vitamin D levels can lead to muscle weakness, slower recovery, and an increased risk of muscle-related injuries. Athletes with optimal Vitamin D levels may experience improved muscle performance and a reduced risk of muscle fatigue.
While there is ongoing research in this area, a study published in the Journal of the International Society of Sports Nutrition in 2019  found that athletes with sufficient Vitamin D levels exhibited better sprinting abilities and overall physical performance compared to those with deficient levels, suggesting a connection between Vitamin D and muscle function.
Mood and Cognitive Health
Maintaining mental well-being and cognitive function is vital for athletes who often face high-pressure situations. Recent studies have explored the potential link between Vitamin D and mood regulation. It is hypothesised that Vitamin D may influence neurotransmitter production and receptors in the brain, impacting mood and cognitive processes.
*Note: This area of research is still developing, and while there is growing evidence, more studies are needed to establish a definitive link between Vitamin D and mental health in athletes.*
Heart health is essential for athletes, as cardiovascular fitness directly impacts performance. Emerging research has begun to investigate the relationship between Vitamin D and cardiovascular health. Adequate Vitamin D levels are associated with a reduced risk of cardiovascular diseases, including hypertension and heart disease.
*Note: As with mood and cognitive health, ongoing research is examining the specifics of how Vitamin D affects heart health, and further studies are required to provide conclusive evidence.*
Incorporating Vitamin D into an athlete’s nutrition plan, whether through sunlight exposure, dietary sources, or supplements, is a prudent strategy to support overall well-being and enhance athletic performance. However, it’s crucial to work with a healthcare professional or nutritionist to determine individualised Vitamin D needs and ensure that supplementation is appropriate.
The supplements that we recommend at Key Nutrition are practitioner-grade supplements that cannot be purchased over the counter and need to be prescribed to individuals due to their high therapeutic doses. The following are some of the brands that we recommend to our clients:
Designs for Health – AU – Liposomal D3
Designs for Health – USA – Vitamin D3 Liquid
Medlab – Nanocelle D3 + K2
Spectrumceuticals D3+MK7 (K2) Liquid Spray
Bioceuticals D3+K2 Spray
1. [Vitamin D status and its association with performance in competitive athletes](https://jissn.biomedcentral.com/articles/10.1186/s12970-019-0328-5)
2. [Vitamin D and the Athlete: Current Perspectives and New Challenges](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037474/)
3. [Vitamin D supplementation reduces the risk of stress fractures in female navy recruits](https://asbmr.onlinelibrary.wiley.com/doi/abs/10.1002/jbmr.3396)