The Sunshine Vitamin

Vitamin D seems to have gotten more media attention than any other vitamin in recent years. Research has shown the importance of this vitamin in bone health, immunity, and prevention of diseases such as breast, prostate, and colon cancers; multiple sclerosis; rheumatoid arthritis; and autoimmune diseases.

How much do we need?

Appropriate intake levels of this vitamin are constantly under debate. The Institute of Medicine currently recommends 600 IU as the RDA (Recommended Dietary Allowance) for everyone ages 1 – 70. Many researchers and healthcare professionals recommend much higher daily doses of Vitamin D for disease prevention. The Tolerable Upper Intake Level is the highest amount of a nutrient that can safely be consumed on a daily basis (these are also set by the Institute of Medicine). The following are the Tolerable Upper Intake Levels for Vitamin D:

Ages 1 – 3            2500 IU

Ages 4 – 8            3000 IU

Ages 9 & up            4000 IU

Where can we get Vitamin D?

There are two ways to obtain Vitamin D: diet and sun exposure. UV light that reaches unprotected skin (skin that is not covered by clothing or sunscreen) results in Vitamin D synthesis. Increased use of sunscreen is protecting us from sunburn and the risk of skin cancer; however, it is also preventing us from getting adequate levels of Vitamin D. Generally, 5 to 30 minutes of unprotected sun exposure to the face, arms, legs, or back between 10 am and 3 pm will make about 200 IU of Vitamin D. (This will depend on your skin’s sensitivity to the sun and the strength of the sun.)

Since it is difficult to judge how much Vitamin D you are getting from sun exposure, it is also tricky to determine how much you need in your diet. Very few foods naturally contain Vitamin D. Fatty fish (salmon, sardines, herring and mackerel) and fish liver oils are the best dietary sources, providing between 40 and 400 IU per serving. Other foods that contain small amounts of this vitamin are egg yolks and mushrooms.

The majority of the Vitamin D in our diet comes from fortified food sources, the main source being milk. One cup of milk will provide approximately 120 IU. Other fortified foods may include orange juices and breakfast cereals. Food labels will show the % of the Daily Value of Vitamin D in one serving. The Daily Value on the food label is outdated; consuming 100% of the Daily Value would provide 400 IU, which we now know is inadequate for disease prevention.

In general, individuals with limited sun exposure must choose to include good sources of Vitamin D in their diet or take a supplement. Supplements and fortified foods may be fortified with either Vitamin D2 or Vitamin D3. Of the two, Vitamin D3 is the better choice as has much higher bioavailability. If you feel that a Vitamin D supplement is necessary for you or your child, talk to your doctor about a safe daily dose. While it is physically impossible to reach toxic levels of Vitamin D from sun exposure, it is certainly possible to ingest dangerous levels of it from taking supplements.

The bottom line is that in order to get enough Vitamin D, you should get yourself and your kids outside for a few minutes in the sun before applying sunscreen. Drink a few glasses of milk each day, try to have fish 2 to 3 times per week, read food labels, and ask your doctor if a Vitamin D3 supplement is a good idea.

 Sources:

National Institutes of Health. “Dietary Supplement Fact Sheet: Vitamin D.”http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

Institute of Medicine, Food and Nutrition Board. “Dietary Reference Intakes for Calcium and Vitamin D.” November 30, 2010.http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D.aspx