Vitamin D Getting Enough Impact of the Sun Media
Your skin is vitally important in the production of vitamin D, which is essential for bone and muscle health, and for preventing osteoporosis. Vitamin D deficiency has also been implicated in some cancers and higher levels of Vitamin D have been associated with decreased rates of multiple sclerosis.
Your skin contains a form of cholesterol known as 7-dehydrocholesterol. When this is exposed to sunlight, it is converted to become an inactive form of vitamin D, called cholecalciferol or vitamin D3.
That vitamin D3 is then picked up by the blood stream and carried to the liver where it is converted to calcitriol (also known as 25-hydroxycholecalciferol), which is the biologically active form of vitamin D. That then circulates in the blood stream to regulate the concentration of calcium and phosphate in your blood.
Vitamin D can also be obtained in some foods, but food only contributes a relatively small part of any person's vitamin D level. Vitamin D3 (cholecalciferol) is present in small amounts in a limited number of foods, including:
- oily fish, such as salmon, trout, mackerel and tuna
- meat, particularly liver
- mushrooms - especially if you leave them in the sun for 15 minutes (!)
- fortified milk
There is some evidence that obtaining Vitamin D naturally from the sun is more efficacious for the body than taking supplements.
Getting enough Vitamin D
How much sun exposure do I need for enough vitamin D?
The sun is the best natural source of vitamin D. Generally, only incidental exposure is needed. How much vitamin D is produced from sunlight depends on the duration of sun exposure, time of day, the date, where you live (specifically the latitude) and your skin tone.
You don't need to tan or burn your skin to get enough vitamin D. Over-exposure can stop the natural production of vitamin D in your skin.
People are at increased risk of low vitamin D may need a slightly increased daily exposure to sunlight. Depending where they live, most Australians will achieve enough vitamin D just through their normal lifestyle.
The easiest way to ensure that you achieve appropriate sun protection AND adequate Vitamin D production is to check the UV levels (this refers to UVB). This is easily done with the use of the Cancer Council SunSmart app or with weather forecasts from the Bureau of Meteorology. You should not get more than 15 minutes direct sun exposure when UV levels are 3 or higher. However, outside of these times, you can obtain direct sun exposure safely and hence manufacture Vitamin D, regardless of the temperature. The more skin you expose, the more Vitamin D will be manufactured.
In southern Australia, winters are cool, so people naturally cover up. In Victoria and Tasmania, there will be almost 4 months (May to August) without appreciable UVB. It is worth exposing skin to winter sun in these regions.
Dermatologists generally recommend use of a facial sunscreen all year around. Even when there is no appreciable UVB in the winter months in southern Australia, there will be exposure to UVA, which also contributes to skin ageing. Therefore, areas of the skin besides the face should be exposed to the sun to generate Vitamin D.
CAUSES OF VITAMIN D DEFICIENCY
Generally, vitamin D deficiency is found in:
- those with naturally dark skin tones (as their skin pigment reduces UV penetration and they need more exposure to sunlight to produce adequate levels of vitamin D)
- people who cover themselves for religious or cultural reasons
- people who are housebound
- the elderly, who are less efficient at making Vitamin D
- babies who are breastfed by mothers with a vitamin D deficiency
- patients with conditions, or who are on medications that affect the production of vitamin D (obesity, liver disease, kidney disease, cystic fibrosis, coeliac disease, inflammatory bowel disease).
If you are in one of these at-risk groups, or are concerned, then see your GP. Your vitamin D levels can be checked with a simple blood test.
Vitamin D supplementation may be required and might be more appropriate than sun exposure in some cases.
CAN I INCREASE MY LEVELS OF VITAMIN D WITHOUT EXPOSING MY SKIN TO THE SUN?
Generally, this is not necessary as your body will produce sufficient vitamin D through incidental exposure to sunlight (your skin will stop producing vitamin D with over-exposure). Your body will store sufficient vitamin D for 30-60 days without sunlight.
Keep in mind that shorter periods of exposure of larger areas of skin to UV radiation are more efficient at producing vitamin D than long or intense periods of exposure. Long periods in the sun do not improve vitamin D levels but certainly increase the risk of skin damage and skin cancer.
Sunscreen and Vitamin D
Using sunscreen will NOT put you at risk of a vitamin D deficiency.
There has been a considerable amount of scientific research conducted on this issue. The results of this research have consistently shown that regular use of sunscreen by people does not affect their levels of vitamin D.
Nevertheless, if you are very sun protected, with use of clothing, hats and sunscreen, your body will not receive the UVB it needs to make Vitamin D. Hence the safest approach to obtain adequate Vitamin D is to expose skin outside the times when the UV index is 3 or more.
How the sun sees you
Produced by Thomas Leveritt, this is an excellent video that demonstrates how the sun's UV rays can affect your skin, and how you can protect it.
Credit: Thomas Leveritt, 2014.
Music: 'Summer in the City - Starcadian remix' by Freedom Fry
- ABC News: 'Vitamin D guidelines revised to help clear up mixed messages with skin cancer risk'
- SBS News: 'Experts warn of sun protection as Aussies boost vitamin D levels'
- Sydney Morning Herald: 'Myth buster: Experts warn our understanding of Vitamin D is just skin deep'
For more information, see also a joint statement issued by the Australasian College of Dermatologists, Cancer Council Australia, Osteoporosis Australia, Endocrine Society of Australia, and the Australian and New Zealand Bone and Mineral Society:
Craig Sinclair, Chair of Cancer Council Australia's Public Health Committee:
"During summer, most Australians have adequate vitamin D levels just from doing typical day-to-day activities, such as walking for a couple of minutes to the car or the shop. However, if you are going outside for more than a few minutes and the UV Index is 3 or above, you need to protect yourself - slip, slop, slap, seek shade and slide on sunnies."
Associate Peter Foley, from the Australasian College of Dermatologists:
"Prolonged sun exposure does not cause vitamin D levels to continue to increase, but it certainly does increase the risk of skin cancer."
Professor Peter Ebeling AO, from Osteoporosis Australia and the Endocrine Society of Australia:
"If you have adequate Vitamin D during summer, then your body can rely on this storage for one to two months."
"For most of the population, any reduction in Vitamin D levels experienced in winter can be corrected at other times of the year when UV levels are higher."
- Media Release: 'How much sun is enough? Experts agree on sun protection and vitamin D'
- Position Statement: Sun Exposure and vitamin D - Risks and benefits