Ever heard the phrase, a little time in the sun will do you some good? It's true. That's because our skin produces vitamin D when it's exposed to ultraviolet light from the sun.

Studies have found that people with low levels of the vitamin are at greater risk for a number of conditions, including heart disease, cancer, depression, multiple sclerosis, and rheumatoid arthritis.

Vitamin D also prevents bone fractures, and the body needs it to absorb calcium.

It doesn't take much sun to get enough vitamin D. For most people, exposing your skin to the midday sun for just 10 minutes several times a week can do the trick.

But during winter in the us and canada, there's not enough ultraviolet light for the skin to make vitamin D.

So northerners may need to rely on a vitamin d supplement or on foods such as fatty fish or fortified milk.

The same goes for folks who are older or have dark skin. They may not be able to make enough vitamin D from the sun.

Just because a little sun is good doesn't mean more is better. If you're outdoors for more than a few minutes, always use sunscreen and cover up to protect yourself against skin cancer and sun damage. Remember that regardless of the sun's benefits, there's no such thing as a healthy tan.