Here comes the sun!
You may have felt tired, in a low mood or lacking in energy over the winter but now with the sun making an appearance we have the chance to up our sunlight and fresh air exposure. Sunshine is good for us as sun exposure helps to satisfy our requirements for vitamin D. Solar ultraviolet B photons are absorbed by 7-dehydrocholesterol in the skin, leading to its transformation to previtamin D3, which is rapidly converted to vitamin D3. Season, latitude, time of day, skin pigmentation, ageing, sunscreen use, and glass all influence the production of vitamin D3 in the skin. Once formed, vitamin D3 is metabolized in the liver and then in the kidney to its biologically active form.
Vitamin D deficiency is becoming more recognised as an epidemic worldwide. Vitamin D deficiency not only causes rickets among children but also osteoporosis among adults and causes the painful bone disease osteomalacia. Vitamin D deficiency has been associated with increased risks of fatal cancers, cardiovascular disease, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes mellitus (see the study below). Although chronic excessive exposure to sunlight increases the risk of nonmelanoma skin cancer, the avoidance of all direct sun exposure increases the risk of vitamin D deficiency, which can have serious consequences. This can be the case with constant use of high factor sunscreens in the Northern hemisphere.
Monitoring your vitamin D concentrations yearly should help reveal vitamin D deficiencies. Sensible sun exposure (usually 5-10 min of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week for pale skins, an hour for darker skins) and increased dietary and supplemental vitamin D intakes are reasonable approaches to guarantee vitamin D sufficiency.
Scientific backup from: Am J Clin Nutr. 2004 Dec;80(6 Suppl):1678S-88S. “Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease.” Holick MF. Image from freeimages.co.uk