Vitamin D

Vitamin D is the only vitamin the body is capable of making with the help of ultraviolet rays from the sun. It is a fat soluble vitamin, so the body can store vitamin D that it doesn’t need immediately for later use.

How it helps

Vitamin D helps the body absorb calcium, which is essential in forming and maintaining strong bones and teeth. It also helps preserve normal blood levels of calcium and phosphorus and plays a role in keeping the immune system healthy. Cod liver oil and vitamin D fortified foods are excellent sources.

What happens if you don’t get enough?

■ bone pain
■ tenderness
■ muscle weakness
■ diarrhea
■ insomnia
■ myopia (nearsightedness)

Vitamin D deficiency in children is seen as rickets, a condition in which the bones become soft and weak, causing the arms and legs to bow, resulting in deformities.

The sun’s UV rays trigger the skin to produce vitamin D. However, as we age, our body’s ability to manufacture vitamin D decreases. People who are confined indoors or who live in northern climates have a higher risk of developing a vitamin D deficiency.

Babies who are breastfed may require vitamin D supplements, because human milk is not a good source of this vitamin.

How much (dosage) should you take?

Males:
■ over 70 years: 15 mcg per day (600 IU)
■ 51 to 70 years: 10 mcg per day (400 IU)
■ 9 to 50 years: 5 mcg per day (200 IU)

Females:
■ over 70 years: 15 mcg per day (600 IU)
■ 51 to 70 years: 10 mcg per day (400 IU)
■ 9 to 50 years: 5 mcg per day (200 IU)

What happens if you take too much?

Too much vitamin D can cause nausea, vomiting, poor appetite, constipation, weakness and weight loss. It can also raise blood levels of calcium, causing mental changes such as confusion and heart rhythm abnormalities.

While supplements may lead to toxic levels of the vitamin, sun exposure and diet are unlikely to cause a reaction.

Can drugs interact with it?

Drugs that can reduce blood levels of vitamin D include:
■ phenytoin and carbamazepine
■ rifampin

Sources of Vitamin D