Shine on Me

Are You Getting Enough “D”?

In the midst of summer, getting some sun exposure — sans sunscreen — may be just what you need. That may sound crazy, in light of what dermatologists are saying, but Americans are currently facing a vitamin D deficiency. 

Vitamin D, a.k.a. “the sunshine vitamin” was once thought simply to prevent rickets in children and severe bone loss in adults. However, recent research suggests that vitamin D plays a major role in overall health.

In 1919 vitamin D was discovered and classified as a fat-soluble vitamin. Today we know it’s actually a hormone that sends chemical messages in the body. For example, vitamin D signals the small intestine to absorb calcium from food and regulates its uptake in bone cells. No other vitamin does what vitamin D can do.

Vitamin D’s Role

In the 1930’s, milk was fortified with vitamin D, effectively eradicating rickets in the US and Europe. Most people thought this resolved the problem, but rickets, which can cause growth retardation and skeletal deformities and increase risk for osteoporosis later in life,1 is only the tip of the iceberg of health problems if you’re deficient in vitamin D.

Vitamin D’s role is to maintain blood concentrations of calcium and phosphorus, producing strong, dense bones, which was once thought to be the only role of vitamin D.2  Within the past 10 years, scientists have determined the role vitamin D plays in chronic diseases, including cancer, autoimmune disease, heart disease, and other infectious diseases.1

Why the Deficiency?

Since the major source of vitamin D is exposure to sunlight, anything that diminishes that exposure will affect the body’s ability to produce vitamin D3, the active form of vitamin D. This includes air pollution, clothing, sunscreen, and tall buildings. Dark skin is another factor; African Americans with very dark skin essentially have an SPF of 15, resulting in a reduction of vitamin D production by as much as 99%. Other common causes include aging, obesity, living at higher latitudes (above 40° N. latitude — Denver is right on the line) and medication.3

Vitamin D and Health

Muscle weakness is also associated with vitamin D deficiency.4  An analysis of five clinical trials concluded that increasing vitamin D intake reduced the risk of the risk of falling in older persons by 22%. This same study showed that vitamin D intakes of 800 IU per day, plus calcium, decreased the frequency of falls.5 

Several studies report living at higher latitudes (above 35 to 40° N. latitude) may increase the risk for cancer, autoimmune diseases such as type 1 diabetes, multiple sclerosis, and Crohn’s disease, compared to people living at lower latitudes who receive more sun exposure. In addition, the risk for high blood pressure and heart disease also increases for those who live at high latitudes.

What Amount is Recommended?

The 1997 adequate intake recommendations for adults are:

Vitamin D, amount/day	Age, years
200 IU (5 mcg)	19–50
400 IU (10 mcg)	51–70
600 IU (15 mcg)	70 & up

Vitamin D is very limited in food sources (see table, below).  A diet high in oily fish (salmon, tuna, and mackerel) and fortified foods may prevent deficiency.

There is considerable research that suggests the current adequate intakes are too low and the levels should be increased to 800 IU/day (20mcg/d).3  However, it is difficult to consume this much through diet, even when consuming fortified foods; consequently smart sun exposure and supplementation may be required to reach the suggested intake. It only takes about 5 to 30 minutes of sun exposure on the arms or legs, twice a week, for sufficient production of vitamin D. This is dependent upon time of day, season, latitude, and skin pigmentation.6

Bottom Line

A simple blood test, called 25 hydroxyvitamin D, is not only the predictor for bone health; it is a predictor of risk for cancer and other infectious diseases.5 The mounting scientific evidence is intriguing, and continues to evolve, showing the many positive health aspects of vitamin D. If you are diligent with a healthful diet that includes foods fortified with vitamin D, consuming oily fish and getting sensible sun exposure, you should be able to maintain adequate vitamin D levels. Work with your dietitian and health care provider to determine if supplementation is right for you.

Vitamin D is not a miracle cure for all that ails you — that pill hasn’t been invented yet! Nevertheless, vitamin D deficiency is underdiagnosed.4

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