Science Questions

When I was training to be a nurse, it was drummed into us that vitamin D comes from the sun. If we're all neurotic about putting sunblocks on, will we not have a lot of people suffering from SAD (seasonal affective disorder)? Margaret in Chelmsford

This is a really interesting debate. There are some people in the media who are saying that we need to get out in the sun as much as possible. It's really difficult because being exposed to too much sun, particularly burning, really does increase your risk of developing skin cancer. We know this from research and rates of skin cancer are set to treble in the UK as a result of too much sun exposure. But we do make vitamin D in our skin when sunlight hits our skin and we can also get vitamin D in our diet. Vitamin D is very important for building healthy bones and teeth and things like that. Deficiency in vitamin D can cause rickets and there's some evidence that it may help to prevent against cancer. So it's a difficult message to try and get across. Yes, it's important to be safe and not to burn in the sun, but at the same time you should try to be sensible about it. Don't go out in the middle of the day when it's really hot, but you'll still get enough sun to keep your levels of vitamin D healthy. SAD is another point, and it causes some people to become depressed if they don't get enough natural bright sunlight. It's not the same as not getting enough vitamin D or over exposure to the sun. It's a slightly different phenomenon.

July 2006