What do I need to know about Vitamin D?

Each month a at Wheaton primary care physician will answer a health question impacting the western suburbs.

Q: I’ve heard a lot about vitamin D and I’m wondering if it’s really important or if it’s just the current “it” vitamin. What do I need to know?

Vitamin D is an important part of a healthy diet. Without it, the body cannot properly absorb calcium and bones become fragile. Recent research suggests there is a relationship between vitamin D and muscle function as well.  Severe vitamin D deficiency can lead to muscle weakness and falls. Many studies also suggest vitamin D deficiencies are associated with diseases like colorectal cancer, high blood pressure, kidney and heart disease.  Also, a recent study done here at Loyola has shown that vitamin D deficiency increases rejection rates in lung transplant patients.

We’ve heard a lot about vitamin D, but some may still wonder—what is it? Really, it’s more like a hormone than a vitamin. And it has quite a trip to become useful to the body. This often begins on the skin where it is naturally found in large amounts. When exposed to ultraviolet B radiation, from the sun, it’s then converted into previtamin that enters in the blood. Once it reaches the kidneys, it is changed to the hormone form of vitamin D, which is then distributed throughout the body. Very few foods naturally contain meaningful levels of vitamin D.  The most common are fatty cold-water fish like salmon, anchovies, sardines and tuna, as well as cod liver oil. Some foods are fortified with the vitamin, especially milk, infant formula, some orange juices, yogurt, cheese and cereal.

Now that you know where vitamin D is found, you might be wondering why people do not get enough. There are several reasons people are vitamin D deficient. The most common are lack of adequate sun exposure, malabsorption and low dietary intake. It’s also interesting to note that melanin in the skin acts as a natural sunblock. So, dark-skinned immigrants moving from warm climates to cold climates are more likely to be vitamin D deficient. For example, Asian Indian immigrants to the United States may have vitamin D deficiency even with an adequate amount of sun exposure.

If you are vitamin D deficient or have an insufficient amount of it there are many types of preparations available for treatment. The two common vitamin D supplements are ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). I suggest vitamin D3 when possible, rather than vitamin D2, because vitamin D3 is the naturally occurring form of the vitamin and it may raise vitamin D levels more effectively.

The recommended dose of vitamin D depends upon the nature and severity of the deficiency. The "ideal" dose of vitamin D is determined by testing the individual's 25OHD level, and increasing the vitamin D dose if the level is not within normal limits.

In people whose level is normal, a dose of 800 International Units of vitamin D per day is usually recommended.

During treatment for vitamin D deficiency, it is important to consume at least 1000 mg of calcium per day (for premenopausal women and men) and 1200 mg per day (for postmenopausal women).

Though vitamin D is important it is only a small part of a healthy diet. For optimal health make sure you are consuming a well-balanced diet, exercising, and to boost that vitamin D level, get outside and enjoy a little bit of sun.