Vitamin D Health Immune System

You know that you need vitamin D for strong bones, but did you realize that vitamin D might also help keep your immune system strong? Scientists now suspect that vitamin D plays a much larger role in keeping your body healthy than previously thought, including regulating immune system health.

A number of studies have shown an association between immune health and vitamin D. Immune system health seems to be negatively affected by low levels of vitamin D, though the exact nature of the relationship in unclear, and some of the studies that have been done are inconclusive.

However, given its known and suspected health benefits, it’s a good idea to make sure that you are getting enough vitamin D, either through sun exposure, dietary sources or supplements.

Vitamin D and the Immune System

How Vitamin D Regulates Your Immune System

Vitamin D appears to play an important role in regulating the functions of your immune system. For example, there is some evidence that people with low vitamin D levels may experience a weakened immune system. In addition, there may be a connection between vitamin D and certain autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis (MS) and diabetes.

One recent study found that patients with MS who took high doses of vitamin D suffered fewer relapses. Doctors suspect that vitamin D helps to diminish the autoimmune response that is thought to cause MS. Other research indicates that people with vitamin D deficiency may be more likely to develop type 1 or type 2 diabetes, and a vitamin D deficiency early in life may also increase the chance of a person eventually developing type 1 diabetes.

Vitamin D and Common Illnesses

There is also evidence that getting an adequate amount of vitamin D can help prevent common illnesses, like the flu and the common cold. In one study, people with vitamin D deficiency were more likely to suffer from colds and the flu than those who got adequate amounts of the vitamin. In addition, low vitamin D has been linked to a great likelihood of respiratory infections in people who also suffer from asthma or COPD (chronic obstructive pulmonary disease).

Currently, the Institute of Medicine recommends that adults get between 200 and 600 international units (IU) of vitamin D each day, depending on age. However, some doctors have suggested that even these recommended amounts of vitamin D are insufficient, and that as many as 1,000 IU of vitamin D each day might be needed for optimal health benefits. If you’re concerned about your vitamin D intake, talk to your doctor about things you can do to address a possible vitamin deficiency.


Johns Hopkins Arthritis Center. (n.d.). Do vitamin D levels affect disease outcomes in rheumatoid arthritis? Retrieved December 17, 2009, from the Johns Hopkins Arthritis Center website:

Lite, J. (2009). Vitamin D deficiency linked to more colds and flu. Retrieved December 17, 2009, from the Scientific American website:

Mathieu, C. et. al. (2005). Vitamin D and diabetes. Retrieved December 17, 2009, from the website:

National Institutes of Health, Office of Dietary Supplements Staff. (2009). Dietary supplement fact sheet: Vitamin D. Retrieved December 15, 2009 from the National Institutes of Health website: