29 May 2012
The recent sunny spell has been good news for athletes hoping for a performance boost. Exposure to UVB rays raises levels of vitamin D in the body, which can help muscles function better, say scientists.
Vitamin D is well known for its role in bone health but recent research suggests it may play a role in muscle metabolism and immune function too. The vitamin is found in relatively few food sources, such as oily fish, butter, eggs and fortified cereals and margarine but it is not possible to meet your requirements from diet alone. It is believed that 60% of adults in the UK are deficient. Several studies suggest that vitamin D deficiency is widespread among athletes too, particularly those in northern latitudes who train mainly indoors or get little sun exposure, or do not consume vitamin D-rich foods. According to recent studies a deficiency reduces muscle function and strength and may also increases the risk of injury and illness risk – all which will have a detrimental effect on your training and performance.
Its fascinating to note the seasonal link between vitamin D levels and performance . A review of studies in 2009) found that performance peaks in the summer months (when vitamin D levels peak) and declines in winter months (when vitamin D levels decline). Peak athletic performance seems to occur when vitamin D levels in the blood approach those obtained by natural, full-body, summer sun exposure, which is around 50 – 70ng/ ml. Getting adequate levels of vitamin D whether from sun exposure or diet is, therefore, important for optimal performance.
How much do you need? There’s no RDA in the UK but the US recommend intakes of 15ug/ day (600IU). If you get very little sun exposure, you should talk to your doctor who may recommend a simple blood test to determine whether you would benefit from vitamin D supplements. Most supplements contain 25ug (1000IU).