Why Does My Body Need Vitamin D?

Back in the 1920s, people prevented rickets by taking cod liver oil. Lucky for us, these days milk is fortified with vitamin D! But vitamin D does more than prevent rickets — do you know what this vitamin does for your body?

Vitamin D helps your body absorb calcium and phosphorus — two minerals that are important in bone and tooth growth. But it doesn’t only help you absorb the minerals; vitamin D helps your body regulate their use. In other words, the vitamin helps tell your body whether to deposit these minerals into your bones or take them out of your bones. If more goes out than goes in, your bones can become soft and weak. Vitamin D is used in treating osteoporosis to help the body retain calcium.

With enough exposure to sunlight, your body can produce its own vitamin D. A fair skinned person can make plenty of vitamin D with just twenty to thirty minutes of sunshine. The darker your skin is, the more sun time you need — up to three hours for extremely dark-skinned people. Why? Skin pigments can filter out ultraviolet rays. Sunscreen, clouds, clothing, and even window glass can filter out UV rays, too.

If you can’t get your vitamin D from sunlight, you can get it from foods. Butter, cream, egg yolks, eggnog, and liver are rich in vitamin D but not necessarily good for you to eat frequently. All milk, from whole milk to skim milk, is fortified with vitamin D. Cod liver oil has plenty of vitamin D, but is also high in vitamin A, which can be bad for you in doses that are too high. You can also find vitamin D in yogurt and tuna fish.

A vitamin D deficiency causes rickets — bone softening. You may lose calcium and protein from bones, leaving them soft and weak. But if you get too much vitamin D, you can end up with calcium deposits in your kidneys, heart, and other organs. Your body will regulate vitamin D production from sun exposure; however, ingesting too much vitamin D bypasses your natural ability to regulate intake.

Vitamin D is also useful in slowing the reproduction of certain types of cancer cells. It is currently being used in research settings only, because it is difficult to use the vitamin therapeutically. Vitamin D may also be helpful in preventing multiple sclerosis — the connection between sunlight exposure and MS is currently being explored. Researchers are also working on using vitamin D to treat psoriasis, some forms of arthritis, and diabetes in young children.

Read about vitamin D and breastfeeding.