There are many different supplements on the market that are suggested to improve exercise performance or the quality of one’s training and it can be difficult to separate the wheat from the chaff. Many of these do not have much evidence to support their claims or are unnecessary, presuming one is eating a varied and balance diet.
However, one supplement that may well be justified is Vitamin D (also known as the Sunlight Vitamin).
As the name suggests the major source of Vitamin D is sunlight, which is somewhat problematic here in sunny old England or if most of your training takes place indoors. As a result, dietary sources become even more important but it is available in relatively few foods. These foods include oily fish, eggs, butter and cereals. As a result, it is suggested that members of the public and athletes are deficient in Vitamin D, particularly during the winter months.
Vitamin D provides many health benefits, such as protection from osteoporosis due to its function of absorbing calcium, hypertension, risk of cardiovascular disease and even asthma attacks in youths. Further to this, Vitamin D, may be beneficial for exercise performance and training.
Firstly, it is involved in muscle metabolism and studies suggest that a deficiency may reduce muscle function and subsequently reducing training quality. What is more, it provides a role within immune function and studies have found that a lack of Vitamin D can increase the risk of upper-respiratory tract infections (colds). This means that time has to be taken off from training, which can be of course detrimental to performance and at the very least, frustrating. Furthermore, a lack of vitamin D may increase the risk of stress fractures due to decreased calcium absorption. Exercise is great for bone health and so is calcium and Vitamin D (calcium absorption). However, during periods of negative energy balance (such as during a weight loss programme), calcium and Vitamin D can become neglected and subsequently lead to reducing bone health.
It is suggested Vitamin D should be supplemented by those who struggle to consume Vitamin D rich-foods. Also, during the winter months there may well be benefits to Vitamin D supplementation and/or if most of your training takes place indoors. The suggested optimal intake range is between 400-800IU/day but this may be too low for adults. It is suggested a daily intake of 1000-2000IU/day is sufficient to meet the needs of most.
Before supplementation, it is recommended that Vitamin D intake is measured via dietary analysis by a Dietician or Nutritionist.