Your Skin, Vitamin D and the Sun
Vitamin D is essential for maintaining strong, healthy bones. In humans, vitamin D is mainly produced in the skin when exposed to sunlight.
A small amount of vitamin D is absorbed through diet, and is found in higher amounts in certain foods:
- 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
A well-functioning liver and kidneys are also necessary to produce vitamin D.
Low vitamin D is called vitamin D deficiency. In adults, persistent vitamin D deficiency over a long period can lead to osteoporosis, where the bones are fragile and can break easily. Osteoporosis is a severe problem, particularly in the elderly, as even minor falls can lead to serious injury.
In children, severe vitamin D deficiency can cause a condition called rickets which causes bowing of the legs and other bone deformities.
Certain groups are at higher risk of vitamin D deficiency:
- People with naturally dark skin
- People who cover themselves for religious or cultural reasons
- People with chronic medical problems, advanced age, or who are housebound
- Babies who are breastfed by mothers with vitamin D deficiency
- People with medical conditions affecting the production of vitamin D (obesity, liver disease, kidney disease, cystic fibrosis, coeliac disease, inflammatory bowel disease)
- People with indoor occupations or night-shift workers
- People who avoid sun exposure for medical or other reasons
A blood test can easily check your vitamin D level.
The sun is the best natural source of vitamin D, but too much sunlight damages the skin and increases the risk of skin cancer. The challenge is getting enough sunlight to produce adequate vitamin D while minimising skin cancer risk.
You don’t need to tan or burn your skin to get enough vitamin D. Most Australians will achieve enough vitamin D just through their normal lifestyle. The duration of recommended sunlight exposure varies based on several factors like the time of day, where you live in the world, your skin tone and the season.
A shorter period of exposure of extensive areas of skin is more efficient at producing vitamin D than long or intense periods of exposure. People with darker skin tones will require longer periods of exposure to have adequate amounts of vitamin D.
During summer when the UV index is 3 or more, you should use a combination of sun protection measures (e.g. sunscreen, broad-brimmed hat, long sleeved clothes) if going outside for more than a few minutes.
In late autumn and winter in parts of Australia where the UV index is below 3 for most of the day, sun protection is not required.
The SunSmart app is available for free (Google Play or Apple App Store) and is a great way to check the UV index and whether sun protection is required.
Vitamin D supplements are oral tablets or capsules which are usually reserved for people who are institutionalised or taking other medications for osteoporosis and have a diet low in calcium. Routine use of vitamin D supplements is not recommended.