Your skin, Vitamin D and the Sun
Your skin is vitally important in the production of Vitamin D, which is essential for bone and muscle health, and for preventing osteoporosis.
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 calcidiol (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 phospate 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 (cholcalciferol) is present in small amounts, in a limited number of foods, including:
- oily fish, such as salmon, trout, mackeral and tuna;
- meat, particularly liver, and
- fortified milk and orange juice.
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.
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;
- The aged, chronically ill people, or others who are housebound;
- Babies who are breastfed by mothers with a vitamin D deficiency; or
- 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.
How much sun exposure do I need for enough vitamin D?
The sun is the best natural source of vitamin D. However, only incidental exposure is needed. You don't need to tan or burn your skin to get enough vitamin D. You only need small doses of sunlight. Over exposure can stop the natural production of vitamin D in your skin. How much vitamin D is produced from sunlight depends on the time of day, where you live in the world and your skin tone.
As mentioned earlier, some people are at increased risk of low vitamin D, so they may need a slightly increased daily exposure to sunlight. Otherwise, the majority of Australians will achieve enough vitamin D just through their normal lifestyle.
During winter, those in northern Australia will need less exposure than those in the south. Much will depend on the UV levels in those regions.
You will need sun protection when UV levels are 3 or higher, so check your weather forecasts in newspapers or online at the Bureau of Meterology.
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). And your body will store sufficient vitamin D for 30-60 days without sunlight.
If you are concerned about vitamin D, talk to your GP. Your GP can order a simple blood test to check if vitamin D levels are low and can advise you about sun exposure, diet and vitamin D supplements.
Keep in mind that shorter period 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.
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 Zealans Bone and Mineral Society
- 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
- 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'