Q. I'm worried I might not be getting enough vitamin D, but should I cut back on or stop using sunscreen?

A. Although it may be true that you're not getting enough vitamin D, cutting back on sunscreen is not the answer—especially in Australia where even limited sun exposure increases our risk of developing skin cancer. That said, vitamin D is a critically important hormone our bodies require to maintain healthy bones and blood calcium levels, and indications are that many Australians aren't getting enough D due to lifestyle factors. Along with the more widespread use of sunscreen, we drive more than we walk, we spend more time at work than we used to, and we play indoors rather than outside.

We need vitamin D to help prevent osteoporosis, depression, high blood pressure and many forms of cancer. You can absorb a very small amount of D by eating oily fish, but the skin produces most of our vitamin D upon direct exposure to the ultraviolet radiation (UVB) in natural sunlight. Even weak sunscreens (SPF 8) or glass block the skin's vitamin D production; however, it's unnecessary to sunbake, as exposure of the hands, face and arms for approximately 10 minutes a few times a week ensures that you produce sufficient vitamin D. Hang up the washing outside, walk to the letterbox to post a letter or water the garden—these are the kinds of brief activities that can give you an adequate dose of vitamin D. Work such tasks into a few mornings or afternoons; I certainly don't advise sun exposure in the middle of the day during summer, and I still recommend avoiding sunburn with sunscreen and other measures.

Despite our climate, certain Australians can't get enough casual exposure to the sun to produce adequate amounts of vitamin D. This is particularly true of the elderly, those who avoid the sun due to skin conditions and people with dark skin. Once produced in the skin, vitamin D needs the liver and kidneys to create the active form, calcitriol, so people with diseases of these organs are also at risk of vitamin D deficiency. If you can't get adequate amounts of D naturally, I recommend a supplement of at least 400 IU (10 mcg) per day.

By Dr Marc Cohen, professor of complementary medicine at Melbourne's RMIT University.