What exactly is vitamin D and how does it influence our health and physical performance?

Vitamin D is both a nutrient that we eat and a hormone that our body produces. It is a fat-soluble vitamin long known to help the body absorb and store calcium and phosphorus; both are crucial for bone development. Laboratory studies also show that vitamin D can reduce cancer cell growth, help control infections, and reduce inflammation. Many of the body's organs and tissues have receptors for vitamin D, suggesting that vitamin D plays an important role beyond bone health, and scientists are actively investigating other possible functions.

Only a few foods naturally contain vitamin D, although some foods are fortified with the vitamin. For most people, taking a dietary supplement is the best way to get enough vitamin D, as it is difficult to get enough through food. Vitamin D supplements are available in two forms: vitamin D2 (“ergocalciferol” or previtamin D) and vitamin D3 (“cholecalciferol”). Both are also naturally occurring forms produced in the presence of the sun's ultraviolet B (UVB) radiation, hence the nickname “sun vitamin.” However, D2 is produced in plants and fungi and D3 is produced in animals, including humans. Vitamin D production in the skin is the most important natural source of vitamin D. However, many people - including athletes - have insufficient vitamin D levels because they live in places where there is little sunlight in the winter, or because they have limited exposure to the sun because they spend most of their time stay indoors. Additionally, people with darker skin tend to have lower levels of vitamin D in their blood because the pigment (melanin) acts like a shadow, reducing the production of vitamin D (and also reducing the harmful effects of sunlight on the skin, including skin cancer).

Did you know that former British cyclist Chris Boardman stopped cycling after being diagnosed with early-stage osteoporosis? An unfortunate end to a great cycling career, but the question is: could this have been avoided?

In Chris' case this is unlikely as the disease ran in his family. But in many cases, osteoporosis — a health condition that weakens bones, making them brittle and increasing the chance of fracture — is largely preventable. Because cycling is not a weight-bearing exercise, it is unlikely that you will be able to prevent the disease through cycling alone. However, one way to prevent osteoporosis is to ensure that you get enough vitamin D.

What other benefits does regular consumption of this vital vitamin have while cycling?

Most importantly it seems to reduce inflammation. Studies show that inflammation increases when an athlete has lower vitamin D levels. Inflammation is thought to be one of the causes of athlete burnout, or “overtraining syndrome.” However, when an athlete maintains normal vitamin D levels through diet and supplementation, inflammation is reduced and so they can recover better after training/competition.

Another benefit of vitamin D is that type II muscle fibers are particularly sensitive to the effects of a vitamin D deficiency. These muscle fibers are essential in activities that require short, sharp movements. So if you want to be better at sprints or quick climbs, you should make sure you get enough vitamin D.

An important part of regeneration and better performance is also the prevention of muscle loss. A person with vitamin D deficiency is more likely to suffer from muscle loss, which reduces the performance of their muscles on the bike. Muscle fibers contract and relax much more slowly, which is essentially another way of saying they don't function as well anymore. In addition, an atrophied muscle increases the risk of chronic pain. As your muscles' performance decreases, your risk of injury also increases. Various studies have been conducted to show the connection between sufficient vitamin D levels and injury prevention and recovery. All of them showed a positive influence of sufficient vitamin D on the risk of injury. If you do injure yourself, whether from a muscle strain or a broken bone from falling off a bike, people who have enough vitamin D are likely to recover more quickly than those who are deficient.

An important aspect of having enough vitamin D is increased oxygen levels. Studies have shown that a person who has sufficient vitamin D levels has higher oxygen consumption, which in turn leads to better breathing. And oxygen is king when cycling.

The above are just a few of the many benefits of adequate vitamin D levels for you as a cyclist - and as a person in general! You can get your vitamin D in a variety of ways. This can be done through food and sensible sun exposure, but you'll probably also need nutritional supplementation. These products can certainly be a helpful addition to your workout routine over the winter.