Vitamin D or the ‘Sunshine’ vitamin is essential for normal bone formation and to prevent osteoporosis. Normal levels are also needed for the proper functioning of virtually every organ in our body, including the brain, heart, muscles, skin and also the immune system. Of particular importance, it has a protective effects, helping to decrease virtually all types cancer including skin cancer.
There are only 3 known sources of Vitamin D:
- Vitamin D Supplements
It is shorter wavelengths of the light that converts 7-dehydrocholesterol into Vitamin D3 in the skin. Whole body exposure to UVB radiation for 15-20 minutes is able to induce the production of approximately 10 000 IU (international units) of Vitamin D and it is able to be stored in the liver for some months.
There are only a few natural sources of Vitamin D including cod liver oil, cheese, egg yolks, mackerel, salmon, tuna and beef liver. As it is not always easy to obtain adequate Vitamin D levels from natural dietary sources alone, many countries fortify foods such as orange juice, milk, yoghurt and cereal with Vitamin D. Most multi-vitamin tablets contain a small amount of Vitamin D or it can be taken on its own, preferably as Vitamin D3.
How much Vitamin D is produced in your skin by sunlight will depend upon various factors such a geographical latitude, season, time of the day, weather conditions and the amount air pollution. It can also depend on the colour of the skin. A paler skin is up to 6 times more efficient in the production of Vitamin D than a darker skin. Those most at risk of a Vitamin D deficiency would include people with a darker skin type who live in dark, cold climates – they would need to take Vitamin D supplements. Also at risk are elderly people who have a thinner skin which is not as efficient in the production of Vitamin D and they generally spend more time indoors.
Other factors such as clothing, lifestyle, workplace and sun avoidance practices all have a strong impact on Vitamin D synthesis. UVB is not able to penetrate through glass so sitting in a sunny spot indoors will not increase your Vitamin D levels.
Can sunscreen prevent me from producing enough Vitamin D?
Most sunblocks block UVB but it is questionable if sunscreen in practice can cause any Vitamin D deficiency. It is very rare that we cover our whole bodies with sunscreen and some areas of the skin are almost always left out i.e. the scalp, around the eyes, etc. Most sunbeds produce mainly UVA radiation which can cause skin cancer and ageing of the skin but do not in fact produce UVB.
How much sun do I need to produce enough Vitamin D?
South Africa has a very sunny climate so we generally only need 15-20 minutes of sun exposure twice a week to our scalps and forearms to produce enough Vitamin D. In winter, it is best to go outdoors in the middle of the day when the UVB radiation is at its highest to get adequate levels of Vitamin D.
If you have any doubt ask your doctor to check your Vitamin D levels in the blood or if you feel you may be in a high-risk category for a Vitamin D deficiency, it is important to take a supplement.
Vitamin D is an essential nutrient for the body to function healthily and it is vitally important to avoid becoming Vitamin D deficient. However, one does not want excessive sun exposure causing premature ageing of the skin and skin cancer. It is therefore a fine balancing act and each person is unique and should take responsibility for ensuring adequate Vitamin D levels while avoiding the known risks associated with too much sun exposure.