Most humans rely on sun exposure to obtain their required vitamin D. With only a few natural sources (mackerel, sardines, irradiated mushrooms), very few foods contain vitamin D and only a few foods are fortified with it. Although chronic excessive exposure to sunlight increases risk of nonmelanoma skin cancer the avoidance of all direct sun exposure increases the risk of vit D deficiency which can have serious consequences. According to a report by Dr Michael Holick of Boston University, a vitamin D deficiency:

• Causes rickets among children
• Exacerbates osteoporosis in adults
• Causes painful bone disease osteomalacia

There is also an associated increase risk of :

• deadly cancers (including colon and breast as vitamin D regulates cell growth)
• Cardiovascular disease
• Crohn’s disease
• Multiple sclerosis
• Rheumatoid arthritis
• Type 1 diabetes mellitus

Aside from the general health benefits there is a new report by John Cannell and colleagues in the the journal Medicine & Science in Sports and Exercise , who reviewed the literature for evidence that vitamin D affects physical and athletic performance. They found that performance peak as vitamin D levels peak and that vitamin D also increases the size and number of Type II (fast twitch) muscle fibers.

However don’t think this is giving you a green card to sunbathe all weekend. To guarantee vitamin D suffiency requires only sensible sun exposure (5-10mins of exposure of the arms and legs or the hands arms and face, 2 or 3 times per week are sufficient). Exposure also needs to be between the hours of 10:00 and 15:00 because this is the only time when enough UVB protons reach the earths surface to produce vitamin D3 in the skin.

So make sure you use schedule your 10minutes wisely this weekend and improve your health and athletic performance with a walk in the sun.