The Download On Vitamin D

By Laura Kruskall, PhD, RD

With summer in full swing and everyone enjoying more outdoor activities, I thought it would be timely to share a complete download on the “sunshine vitamin.”

What does Vitamin D do?

Everyone knows that Vitamin D helps build and maintain strong bones, but recent research findings suggest that Vitamin D also plays a role in an increasing number of vital bodily functions, including cellular growth, immunity, protein synthesis, nutrient absorption, pregnancy/nursing, and influences the risk and/or progression of medical conditions such as cancer, diabetes, influenza, hypertension, cardiovascular diseases, periodontal disease, Parkinson’s Disease, depression, autoimmune disorders, and chronic pain. From this newfound appreciation for Vitamin D, the Institute of Medicine (IOM) increased the Dietary Reference Intake (DRI) for vitamin D to 600 IU/day for individuals less than 70 years of age and 800 IU/day for those over 70 years of age.

But can’t I get enough Vitamin D from sunlight?

Vitamin D is commonly referred to as the “sunlight vitamin” because it is the only one known to be synthesized in the body in response to direct sunlight exposure. This process involves the coordinated activity of the skin, liver, and kidneys. As long as these organs are working properly and you get sunlight exposure, then your body can make sufficient Vitamin D to promote optimum health. In order to get adequate Vitamin D from sunlight, your face, arms, or legs must be exposed to the sun for five to 30 minutes for at least two days per week. Unfortunately, there is a potential drawback to obtaining all your Vitamin D from sunlight exposure, specifically your risk of developing skin cancer increases in proportion to the amount of time your skin is exposed to the UV rays in sunlight. Of course, you can reduce your risk of getting skin cancer by wearing a high-SPF sunscreen, but this will also reduce the amount of Vitamin D you produce.

I want to extra cautious when it comes to skin cancer, now what do I do?

In lieu of repeated direct sunlight exposure, you can consume Vitamin D in foods and/or dietary supplements. Although not abundant, there are some foods that naturally containing Vitamin D, including fatty fish, eggs, and mushrooms. There are also foods that are fortified with Vitamin D, such as milk, some dairy products, orange juice, and cereals. While it is possible to consume the DRI for Vitamin D with natural and fortified foods, one must eat these foods on a regular basis. For those of you that choose not to eat these foods regularly there is another option, you can take dietary supplements of Vitamin D, which are readily available and relatively inexpensive. Vitamin D in the supplemental form is often found with calcium since both nutrients are important for bone health. The supplemental form seems to be just as effective as that found in food, so this may be a preferred intake route for many individuals.

How can I tell if I’m getting enough Vitamin D?

There is a blood test that can estimate the level of Vitamin D in your body, however it is a relatively expensive test that is often not covered by insurance and it must be requested by your physician. One reason for this is that there still exists some controversy about what is an appropriate level of Vitamin D in blood serum for optimal health, so routinely conducting this test has not yet become widely accepted in the scientific/medical community. For example, the IOM says that a serum Vitamin D content of 20 ng/mL is considered healthy, but many research scientists feel that a much higher level is required for optimal health.

What’s the Bottom Line?

Vitamin D participates in a myriad of body functions and must be consumed in the diet and/or synthesized by your body. The Institute of Medicine recently increased its recommendations for the amount of Vitamin D needed by most people and even suggested how much Vitamin D in your blood is considered healthy. Until more research is completed and a more definitive conclusion about optimal serum levels of Vitamin D can be made, it is probably prudent to use the Institute of Medicine’s conservative recommendations for Vitamin D intake (600 IU for those under 70 years and 800 IU for those over 70 years of age). It is your individual choice whether to receive Vitamin D from food/supplements or sunlight.

For more information, visit:

National Institutes of Health Office of Dietary Supplements

The Mayo Clinic

National Dairy Council

National Cancer Institute at the National Institutes of Health