The importance of vitamin D
Vitamin D is known as the sunshine vitamin because your body makes it when your skin is exposed to sunlight (the sun’s UVB rays promote the synthesis of vitamin D3 in our skin). The good news is sunshine is something we can get more of as the summer’s hotter months kick in – as long as we’re sensible about our sun exposure and protecting ourselves from the risk of skin cancer.
It’s important for us to maintain healthy vitamin D levels for things like the health of our bones and teeth, and to help regulate the absorption of minerals like calcium and phosphate in the body. Vitamin D also plays a role in boosting the function of our immune system, as evidenced in this 2011 article from the Journal of Investigative medicine.
What is vitamin D and what does it do?
There is a group of D vitamins, as outlined by DermNet.
- Vitamin D2 is made from ergosterol in plants that are exposed to the sun’s UV rays.
- Vitamin D3 comes from different types of foods (in small amounts) and produced in skin when sun acts on the compound 7-dehydrocholesterol.
- Calcitriol is the bio-active hormonal form of vitamin D, which is converted from vitamin D3 by our liver and kidneys.
The skin is uniquely important in synthesising, storing and releasing vitamin D to circulate in our bloodstream, it says.
According to the Ministry of Health, about 5% of New Zealand adults have a vitamin D deficiency and another 27% of our adults have less than the recommended level of vitamin D in their blood.
If you get lower levels of sun exposure, or regularly wear clothing that covers more of your body, you’re more at risk of having a vitamin D deficiency. You might also be deficient if your skin is very dark, if you’re an older adult, are breastfeeding, you have a liver or kidney condition, or take medication that affects your levels of vitamin D, the ministry says.
Fortunately sun on your skin isn’t the only way to get vitamin D – although there are few foods contain it, there are some you can add to your diet to boost your vitamin D levels:
- Oily fish such as salmon, tuna and mackerel, eel, and fish liver oils
- Beef liver
- Some mushrooms
- Fortified dairy products and cereals (have vitamin D added)
- Vitamin D supplements