Sun and vitamin D
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- Our skin produces vitamin D when exposed to ultra-violet (UV) rays from the sun.
- However, the amount of time you need in the sun to make enough vitamin D depends on your skin type, time of day or year and where you are in the world.
- You don’t need to sunbathe to get enough vitamin D. Most people in the UK can make enough vitamin D by spending short periods of time in the sun in their daily life without sun protection.
We all need vitamin D because it helps build and maintain strong bones. Our bodies produce vitamin D when our skin is exposed to direct sunlight. This is the main way of getting this vitamin, but it can also be found in foods such as egg yolks, fresh or tinned oily fish like mackerel and sardines, fish liver oils and some margarines and fortified cereals.
In more serious cases, a lack of vitamin D can lead to rickets in children, and a condition that leads to softer bones called osteomalacia in adults.
In the UK, the government recommends people at risk of having low vitamin D take a supplement, and that everyone think about doing this between October and the end of March, when the sun’s rays are less strong.
How much sun do we need to get enough vitamin D?
There is a balance to be struck when spending time in the sun. Sunlight helps us produce vitamin D, but too much can cause skin cancer. This balance is different for each person and depends on your skin type, the time of day or year and where you are in the world.
The amount of time you need in the sun is probably less than you think and may be just minutes. One study estimated that 9 minutes of lunchtime sunlight each day in the UK would be enough for people with lighter skin tones .This is a useful but rough estimate which makes lots of assumptions, for example that people would be in shorts and t-shirts for June to August, while only having their hands and faces exposed from March to June and for September.
People with darker skin tones need to spend more time in the sun to get enough vitamin D. With the same conditions, people with darker skin that hardly ever burns and easily tans, may need 25 minutes.
People who are most likely to be at risk of vitamin D deficiency include:
- People with naturally brown or black skin from African, Afro-Caribbean or South Asian backgrounds.
- People who have low or no exposure to the sun. For example, those who are housebound, confined indoors or who usually wear clothes that covers up most of their skin when outdoors.
- People over the age of 65
- Pregnant and breastfeeding women
- Babies and children aged under 4
The Government recommends that people within these groups should take a 10 microgram supplement of vitamin D a day throughout the year.
This NHS page has more information on vitamin D: http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Vitamin-D.aspx
Talk to your GP about vitamin D supplements if you are worried about your vitamin D levels.
Scientific Advisory Commitee on Nutrition. Vitamin D and Health. http://dermatology.jwatch.org/cgi/content/full/2009/522/1. [Accessed January 2019]
National Institute for Health and Care Excellence (NICE). Sunlight exposure: risks and benefits. https://www.nice.org.uk/guidance/ng34/chapter/supporting-information-for.... [Accessed January 2019]
International Agency for Research on Cancer. Radiation. Vol 100 (2012).
Felton S. J. et al. Concurrent beneficial (vitamin D production) and hazardous (cutaneous DNA damage) impact of repeated low-level summer sunlight exposures. Br J Dermatol. 175(6), 1320-1328 (2016). doi:10.1111/bjd.14863.
Farrar MD, Webb AR, Kift R, et al. Efficacy of a dose range of simulated sunlight exposures in raising vitamin D status in South Asian adults: Implications for targeted guidance on sun exposure. Am J Clin Nutr. 97(6), 1210-1216 (2013). doi:10.3945/ajcn.112.052639.
Webb. A.R. et al. Meeting Vitamin D Requirements in White Caucasians at UK Latitudes: Providing a Choice. Nutrients. 10(4), 497 (2018)
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This information is based partly on work we funded at the University of Manchester.
They are running a short, confidential survey about UV and vitamin D.