Most of us know that vitamin D is crucial to bone health, but now it's been shown that insufficient levels can cause or increase the risk of developing a number of health problems, such as high blood pressure, diabetes, metabolic syndrome, and low HDL cholesterol (good cholesterol). Recent studies report that about 70% kids in the United States have low vitamin D levels.

It's believed that vitamin D is also crucial for maintaining the body's immune system, and that low levels increase the risk of heart disease and other cardiovascular health problems, as well as some cancers.

The two main forms of vitamin D are D2 (or ergocalciferol, the main form of vitamin D in foods), which is made by plants and fungi, and D3 (cholecalciferol), made by the body when our skin is exposed to ultraviolet light.

A few foods are rich in vitamin D, such as cod liver oil, egg yolks, cheese, and fatty fish (like salmon, mackerel, and tuna or sardines canned in oil). Vitamin D-fortified foods include milk, orange juice, margarine, and some cereals. Traditionally, milk has been the main source of vitamin D for kids, but fewer kids now drink much milk every day.

Another likely risk factor for low vitamin D levels is the 3-4 hours of TV and computer time many kids get each day. Vitamin D is called the "sunshine vitamin" because ultraviolet rays absorbed by the skin help the body make a usable form of vitamin D — so kids who are parked inside day after day aren't getting these natural "doses" of vitamin D the way kids did in the past.

What This Means to You

Low vitamin D levels can be harmful to a child's health, so parents should try to get kids to drink more milk or take a vitamin D supplement — and decrease the hours they spend indoors in front of a screen.

Although the body also makes vitamin D when the skin is exposed to sunlight, it can be hard to gauge just how much sunshine is safe and effective for an individual child. So shoot for giving your kids three servings of low-fat or fat-free fortified milk, which has about 125 IU of vitamin D added.

Supplements are available as vitamin D2 or D3, and while both raise vitamin D blood levels, D3 supplements appear to be more effective and long lasting.

From KidsHealth.com