BAD position statement 2009
On this page you will find some advice about the sun, skin cancer prevention and vitamin D. As well as some general advice, you can also read a summary of the evidence (click here) on which we base our advice.
2009: BAD position of vitamin D: In recent months there has been much debate about the pros and cons of sunshine for your health.
We know that UV light from the sun and sunbeds can increase risk of skin cancer. However, sunlight also helps the skin on our body to produce vitamin D.
A lack of vitamin D may cause health issues in some people. There is good evidence that vitamin D helps to keep bones healthy. It has also been suggested that vitamin D may help to prevent serious diseases such as cancer, various forms of arthritis and autoimmune diseases. This is an area of considerable research, as there are a large number of questions that still need to be answered, including whether enough vitamin D can be made from sunlight on our skin to reduce the risk of getting these diseases. On the other hand the link between skin cancer and the sun, is proven and well documented.
We recognize that it can be hard to get the required level of vitamin D from the diet alone, which is why we do not say you should avoid the sun altogether.
Unfortunately, we can’t give a precise level of sun exposure that will safely provide you with vitamin D, while also not putting you at risk of skin cancer. This is because there are so many variables – for example, your personal skin type, the geographical location, time of day, weather conditions and more.
It is therefore difficult to quantify how much sun it takes to damage the skin, how much sun it takes for each individual to make optimum amounts of vitamin D, or furthermore to combine the two and define a safe level of sun exposure that allows each person to get the recommended level of vitamin D without suffering skin damage. We do know, however, that once your body has produced its maximum level of vitamin D, extra sunlight does not increase production and will result in skin damage.
Dermatologists are at the forefront of treating skin cancer, and therefore cannot recommend deliberate sun exposure as a safe means of getting vitamin D. A few points to consider are that:
You can get vitamin D from other sources, such as your diet and supplements
It is a fact that UV light from the sun causes skin cancer
Much of the evidence regarding health benefits of high levels of vitamin D require much more research to define what the optimum levels are and how best to achieve these levels.
We therefore currently advise that you should not sunbathe to increase your vitamin D levels as you may increase your risk of skin cancer in doing so. Small amounts of incidental sunlight, as you might get through your daily activities, may help to boost your vitamin D levels.
However, if you are at high risk of skin cancer, you should make protecting your skin in the sun a priority, and look to get as much vitamin D as possible from other sources, such as your diet and supplements, rather than placing yourself at higher risk from skin cancer. Those at high risk include:
people with very fair skin that easily burns
people with a personal or family history of skin cancer
people with lots of moles (more than 50) or
if you are being treated with immunosuppressive drugs.
Much research is being done by dermatologists and other doctors in this area and into the role of vitamin D in disease prevention. So the sensible advice is to get some sunshine as you go about your daily life without getting a heavy tan or burning, and to get vitamin D through your diet. Some foods are fortified with vitamin D (for example some yoghurts, margarine and cereals) and others, such as oily fish, are naturally rich in vitamin D. You can also take a vitamin supplement containing vitamin D, such as a multivitamin or cod liver oil, available from a pharmacist.
Remember that your skin will produce plenty of vitamin D long before it starts to burn.
Weighing up the evidence
Evidence relating to sun safety cannot be interpreted in isolation from the increasing, but sometimes contradictory, volume of evidence surrounding the risks to health from vitamin D deficiency and its link to sun avoidance.
The message itself is not easily definable, as a number of variables, such as the geographical location, time of day, weather conditions and the individual’s skin colour, all contribute to the net effect of the sun on the skin.
It is therefore difficult to quantify how much sun it takes to damage the skin, how much sun it takes to obtain an individual’s optimum vitamin D level, or furthermore to combine the two and define a safe level of sun exposure that allows a person to obtain the recommended level of vitamin D without suffering skin damage.
i) Physiology of Vitamin D
Vitamin D is produced in the skin in response to ultraviolet radiation (UVR). This action of UVR on the skin is the main source of vitamin D in humans, and vitamin D status reflects sun exposure over the preceding month or so. There is seasonal variation in UVR, and vitamin D levels reflect changes in outdoor behaviour as well as UVR levels. Production of vitamin D due to UV exposure is limited, because pre-vitamin D and vitamin D are photolabile, no matter how long someone is exposed to sunlight. Hence it is simply not possible to synthesize large stocks of vitamin D by prolonged exposure to the sun (Webb et al., 1989, Dahl, 2004). That is, there is not a clear consistent linear dose - response relationship between UVR exposure and vitamin D levels. Indeed with prolonged sunlight exposure the production of vitamin D actually stops after a certain period. There is considerable debate as to the level of vitamin D required for normal physiological function. Some authorities have the view that plasma levels of above 30 microgram/l of 25 hydroxyvitamin D are required for normal physiological function (Feskanich et al., 2004). This includes calcium homeostasis and normal bone health. In northern latitudes, and in winter, many individuals are vitamin D deficient by these definitions. Some groups are more susceptible to vitamin D deficiency and these include breast fed babies, the elderly, persons with limited sun exposure, and those with malabsorption syndromes, obesity or dark skin.
ii) Health benefits of vitamin D and health risks from vitamin D deficiency
Higher vitamin D levels may have health benefits, and so it has been suggested that additional UVR exposure and / or vitamin D supplements may be necessary; for example, vitamin D supplements of 25 micrograms (µg) (1,000 IU) in those under one year, 50 µg in children up to 13, and 50 µg (2000 IU) in adults, including during pregnancy and lactation (Cranney, 2007). It is clear that high vitamin D levels benefit bone health. A recent evidence-based review of research concluded that supplements of both vitamin D3 (at around 20 micrograms/day) and calcium (500-1200 micrograms/day) decreased the risk of falls, fractures, and bone loss in elderly individuals aged 62 to 85 years (Cranney, 2007). It has been suggested that vitamin D may also reduce the risk of internal malignancy (Giovannucci, 2005; Freedman et al., 2007; Skinner, 2008; Lu et al., 2008; Stolzenberg-Solomon, 2009; Ahn et al., 2008; Khazai et al., 2008). However, a WHO IARC working group paper concluded that there was insufficient evidence to support conclusively the relationship between vitamin D levels and colo-rectal and breast cancer, and none to support a relationship to prostatic cancer. Two studies of dietary supplementation with 10 and 21 micrograms of vitamin D failed to influence the incidence of colo-rectal or breast cancer, but supplementation with up to 20 micrograms of vitamin D reduced all cause mortality in the over 50 age group. It is possible, but unproven, that high vitamin D levels may reduce disease progression in established malignancy. Controversially, very high levels of vitamin D are associated with increased mortality from cardiovascular disease (IARC Reports, 2008). Other adverse health issues associated with low vitamin D levels include multiple sclerosis, hypertension, diabetes and autoimmune disorders (Moan et al., 2008; Diffey, 2006). Whilst there are suggestions of benefit from high vitamin D levels, these health benefits are as yet unproven. The 2008 IARC report concluded that for the time being, the definition of vitamin D deficiency should relate to the prevention of rickets, osteomalacia or muscular pain as opposed to internal malignancies. However, this is an emerging area of research which may support the role of vitamin D in disease prevention in future studies.
iii) The arguments
a) It has been suggested that the potential benefits of exposure to sunlight may outweigh the widely publicized adverse effects on the incidence of skin cancer (Ness et al., 1999). As indicated above, the evidence for benefit of UVR exposure acting through vitamin D is contradictory, whilst the evidence for UVR exposure as a cause of skin cancer is incontrovertible.
b) Some have argued that there is little evidence that sun avoidance measures prevent melanoma (Shuster, 2008) and that there is no reduction in the incidence of melanoma with sunscreen use. Almost all authorities accept that there is a direct link between UVR exposure and melanoma (Menzies, 2008). There are convincing data that sunscreen use has little influence on vitamin D status (Marks, 1995).
c) At the same time, it has been suggested that advice aimed at reducing the frequency of episodes of sunburn may have the net effect of reducing vitamin D levels. As indicated above, this is unlikely to be a significant factor because of the very short period of time in the sun needed for maximum vitamin D synthesis.
d) Finally, a lack of good prospective studies that quantify the potential benefits versus the risks of increasing vitamin D by UVR exposure to allow clinicians, patients, healthy individuals and policy makers to decide on personal and population guidance on this issue, is a major current limitation.
iv) Vitamin D Recommended Daily Allowance (RDA)
The minimal requirement for vitamin D is dependent on many factors such as latitude, personal lifestyle (including smoking and body mass index) skin type and the season. It is thus not possible to give a precise figure of dietary supplementation to avoid vitamin D deficiency but the range of vitamin D intakes required to ensure maintenance of wintertime vitamin D status of 20 to 40 year old adults, considering a variety of sun exposure preferences, is between 7.2 and 41.1 micrograms/day. Government guidelines say people between the ages of 51 and 70 should get 400 International Units (IU) (10 micrograms) of vitamin D daily, and those ages 71 and older, 600 IU. In adult patients at high risk, daily vitamin D3 intake should be 800–1000 IU or 50,000 IU vitamin D3 per month (Kullavanijaya and Lim 2005).
v) The need for balance
There are clear and robust data linking skin cancer and UVR. The data regarding the health benefits of vitamin D are emerging, but are still unclear. Sun safety messages must therefore be tailored to take into account this growing area of research, and should influence but not replace sun safety messages.
People should not be advised to forsake photoprotection for cutaneous vitamin D supplementation. Oral supplementation of vitamin D, through diet or dietary supplements is an additional means of achieving adequate vitamin D levels.