PAMF Health Blog

Be Well, Be Well Informed

Vitamin D Deficiency: What to Know

Posted on Nov 5, 2014


Vitamin D  colorful word on the wooden background

Are you fully protecting your bones? If you’re not getting enough vitamin D, you’re not – no matter how much calcium you or your kids get from milk, cheese or yogurt.

Sayali Ranadive, M.D., a specialist in pediatric endocrinology at the Palo Alto Medical Foundation, explains the important role vitamin D plays in our health, and why many Americans — both adults and children — suffer vitamin D deficiency, but don’t know it.

“Vitamin D is so important because it allows our bodies to absorb calcium,” says Dr. Ranadive. “Even if we get enough calcium in our diet, without vitamin D, we cannot efficiently absorb the calcium from our intestine.”

Vitamin D deficiency does not cause any outward symptoms, but over time, it leads to weak bones, and increases risk of fractures.

In addition, ongoing research suggests that vitamin D may help protect against cancer, improve immune function, and stimulate insulin production, Dr. Ranadive says.

Why do we have trouble getting enough vitamin D?

Our bodies primarily get vitamin D from exposure to sunlight. Ultraviolet B rays trigger vitamin D synthesis in our skin. In the U.S., low vitamin D levels are common because at our latitude, the angle at which the sun’s rays are received does not allow for enough UVB exposure. Also, dark skin, sunscreen, age over 50, and certain medical conditions and medications reduce the skin’s ability to make vitamin D.

Very few foods naturally contain vitamin D. Milk and other dairy products are fortified with vitamin D. Still, Dr. Ranadive says most people do not consume enough foods that are rich in vitamin D to meet their daily needs.

How much vitamin D is enough?

The National Institutes of Health’s daily recommendation for most most children and adults is 600 IU of vitamin D a day. But the only way to really know if you’re getting enough is to look at the level of vitamin D in your blood.

There is a lot of confusion and debate about what level of vitamin D in the blood is sufficient to meet all the body’s needs, Dr. Ranadive says. However, doctors do know that the body’s requirement for vitamin D is higher during times of rapid change such as growth spurts, puberty and pregnancy. As a result, The Endocrine Society recommends that children be screened for vitamin D deficiency during growth spurts and puberty. The guidelines suggest that adults be screened if their dietary history, lack of sun-exposure or medical conditions increases their risk.

How do you prevent vitamin D deficiency?

“Most people in the U.S. need to eat foods with vitamin D and take a supplement to maintain a healthy level of vitamin D for the long-term,” says Dr. Ranadive.

If you’re concerned that your children are not getting enough vitamin D, ask the pediatrician to test their blood levels. The doctor can also advise whether your children should take a supplement or simply up their vitamin D through fortified foods.

Ranadive Sayali Ranadive, M.D., is a pediatric endocrinologist at the Palo Alto Medical Foundation.