Vitamin D

Vitamin D, often called the " sunshine vitamin ," is crucial for athletes. It plays several essential roles that affect physical performance, recovery, and overall health. If you're not getting enough sun exposure or getting enough vitamin D from your diet, a vitamin D supplement can help support your recovery, athletic performance, and bone health.

Vitamin D synthesis by the body: explanations

Vitamin D, better defined as a fat-soluble prohormone rather than a true vitamin, exists in two forms important to humans:

• Vitamin D2 (or ergocalciferol), produced naturally by plants
• Vitamin D3 (or cholecalciferol) which is synthesized by the skin when exposed to ultraviolet B (UVB) rays from the sun

Both forms can also be produced synthetically and used as a vitamin D dietary supplement. This vitamin plays a key role in many vital processes . As a hormone, it ensures optimal mineralization of bones during growth and throughout life for their renewal. It also modulates the intestinal absorption of calcium, thus contributing to the stability of calcium levels in the blood and tissues (1). Vitamin D can therefore be obtained through food, via a health food supplement or synthesized by the skin under the effect of sunlight. The endogenous production of vitamin D in the skin is a neosynthesis that occurs mainly in the epidermis. This vitamin D is then stored in the liver, muscles and fatty tissues, and is then used by the body during less sunny periods. Factors such as the season, the time of sun exposure and the latitude can influence this synthesis.

Vitamin D food supplement: What are the benefits?

Bone health

Bone health is essential for athletes because strong bones are less likely to suffer fractures and other physical activity-related injuries. Vitamin D is essential for the absorption of calcium in the intestine, a mineral vital for the formation and maintenance of bone structure. Without adequate vitamin D, calcium absorption from the intestine decreases significantly, which can lead to weak bones and an increased risk of fractures . Vitamin D also helps regulate phosphorus , another mineral important for bone health. Together, calcium and phosphorus contribute to bone density and strength, which is crucial for athletes under high physical stress. Vitamin K is also involved in blood clotting and circulation, which are key elements for recovery.

Muscle performance

Whether it's endurance or explosive strength, a vitamin D supplement will influence muscle health by facilitating protein synthesis and influencing muscle fiber growth . It plays a role in the muscle contraction process through its ability to regulate intracellular calcium levels, which are necessary for muscle contraction. Adequate vitamin D levels maintain neuromuscular function and may reduce the risk of muscle loss with age. Vitamin D is also linked to improved muscle strength and a reduced risk of falls and injuries , especially in older athletes. The same is true for vitamin B , which is involved in the synthesis of nucleic acids, which are essential for muscle cell growth.

Reduction of inflammation

Managing inflammation is essential for post-workout recovery and preventing chronic pain that can result from regular exercise. Vitamin D has anti-inflammatory properties that help modulate the immune response. It influences the production of cytokines, proteins that play a role in inflammation. By regulating the production of inflammatory and anti-inflammatory cytokines, a vitamin D supplement can reduce systemic inflammation and improve muscle recovery after exercise . This can help prevent muscle soreness at the beginning and end of a workout, as well as reduce the risk of long-term injuries. It is used in conjunction with vitamin E , which reduces oxidative stress in cells.

Immune support

A strong immune system is crucial for athletes, as it helps prevent illnesses that can interrupt training and competition. Vitamin C and vitamin D are known for their role in regulating and supporting the immune system . They help activate the body's immune defenses by modulating T cells and macrophages, which are key components of the immune response. Vitamin D thus influences the activity and function of T cells, which are essential for an effective adaptive immune response . It also helps prevent excessive immune responses that can lead to chronic inflammation, while supporting a robust immune response against pathogens.

Why take a vitamin D supplement?

If we define a vitamin as an essential substance not produced endogenously by the body, vitamin D is an exception. Indeed, it is synthesized in the skin by the effect of UVB rays acting on 7-dehydrocholesterol, before being transformed by hydroxylation in the liver and kidneys (2). Thus, its function is closer to that of steroid hormones (such as ZMA supplements that help maintain natural testosterone levels), since it binds to vitamin D receptors throughout the body. However, increasing urbanization and modern lifestyles often lead to a reduction in sun exposure , limiting our skin's ability to produce vitamin D. In addition, climate change may make extreme weather more frequent, causing people to stay indoors more or to use sunscreen to protect themselves from intense UVB rays, further reducing the exposure necessary for vitamin D synthesis . Therefore, if these trends continue, vitamin D could become a true vitamin requiring exogenous intake, that is, via a vitamin D food supplement or multivitamins that contain it.

Sources:

(1) https://www.anses.fr/fr/content/vitamine-d-pourquoi-et-comment-assure-un-apport-suffisant

(2) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3024173/