During the winter months, all adults should take a supplement of 600IU of vitamin D per day. This is in accordance with the US guidelines
A recent Telegraph report suggested that at least 1 in 5 Britons may be deficient in vitamin D. The Department of Health does not currently any vitamin D supplements for the 5-64 age category. However, for adults aged 65 and over, and for adults who are housebound the Department of Health recommends a supplement of 400IU a day.
This advice is outdates. Evidence shows that it is impossible to produce vitamin D in the skin between October and March in the UK. This is in part due to our geographical location, combined with modern lifestyles such that people spend more time indoors and cover up more. In fact, recent official public health advice to avoid the sun and always wear suncream prevents people making vitamin D even when their skin is exposed.
Cancer charities and public health officials now recommend moderate sun exposure for short periods on sunny days.
The Vitamin D Association recommends short periods (for a minimum of 10 minutes) of exposing unprotected skin to bright sunlight during the middle of the day, but never allowing the skin to burn. Darker skinned adults will need to expose their unprotected skin to sunlight for longer because their skin takes longer to synthesise vitamin D.