Vitamin D: The Sunshine Vitamin

Vitamin D, in the true sense, is actually a hormone, not a vitamin. The human body can synthesize vitamin D as long as we are exposed to enough sunlight. This is why vitamin D is known as the “sunshine vitamin.” We can also get it through specific foods in our diet and supplements.

When UVB rays from the sun hit our skin, an inactive form of vitamin D is produced. This inactive form then travels to the kidney where it is converted to the active form, known as 1,25-dihydroxyvitamin D, which the body can use for many purposes.

Health Risks of Vitamin D Deficiency

Researchers have discovered that there are vitamin D receptors in all tissues in the human body. This means that these tissues, including the heart, brain, muscle and intestines, all need vitamin D to function properly.

Vitamin D: The Sunshine Vitamin

We used to think that the only role of vitamin D was to regulate blood levels of phosphorus and calcium to keep our bones strong and healthy. Over the past several years, however, researchers have discovered that this hormone plays a much bigger role than just bone health. They now know that the sunshine vitamin enhances our immune system by creating a resistance to chronic diseases such as colon cancer, cardiovascular disease, obesity, diabetes, depression and Alzheimer’s.

In addition, low levels of vitamin D have shown to be a risk factor for cognitive decline in the elderly. One study looked at 6,257 elderly women and found that those with low vitamin D levels had an increased risk of cognitive impairment.

Causes of Vitamin D Deficiency

If vitamin D is so easy to obtain from sunlight, diet and supplements then why is it estimated that one billion people worldwide are deficient in it? Some researchers suggest the fear of skin cancer from UV rays is causing people to avoid the sun or use sunblock, or that our lifestyles have evolved to be indoors more often, all of which prevents vitamin D production. Ethnicity plays a role as well. The darker a person’s skin color, the more sun exposure they need to obtain sufficient levels of vitamin D. For example, in the United States African Americans have been found to have lower serum levels of vitamin D than Caucasians.

In addition, there are limited foods that contain naturally occurring vitamin D, mainly wild-caught oily fish (salmon, mackerel, bluefish, and canned tuna) and egg yolks. There are also fortified foods such as milk, baby formula, cereal and orange juice. If these foods are not consumed on a regular basis, levels could drop. Still, experts claim that 90 percent of our vitamin D comes from sun exposure alone.

Symptoms of Vitamin D Deficiency

Bone pain and muscle weakness can be a sign of vitamin D deficiency. However, the symptoms are often unnoticeable until a greater complication is present.

Know Your Vitamin D Levels

Now that we know the importance of maintaining optimal vitamin D levels, how do we find out our own levels? Fortunately, there is a blood test which can determine your status.


2.    Slinin Y, Paudel M: Association Between Serum 25(OH) Vitamin D and the Risk of Cognitive Decline in Older Women. J Gerontol A Biol Sci Med Sci. 2012; gls075v1-gls075.
3.    Holick MF, Chen TC, Lu Z, Sauter E.Vitamin D and Skin Physioology: a D-lightful story. J Bone Miner Res. 2007 Dec;22 Suppl 2:V28-33.

Vitamin D Sources

The best way to get vitamin D is through the sun. We absorb large amounts of vitamin D in a short amount of time when exposed to UVB rays. There are many factors that affect how much vitamin D we can produce from UVB rays, including the time of day, latitude, time of year, skin type and age. Someone above 60 years of age requires four times more exposure than someone in their 20s.

There are also vitamin D supplements. The amount of vitamin D necessary to raise levels from deficiency to a normal range is very controversial and many experts have varying opinions. Again, there are many factors that come in to play such as age, weight, sun exposure, other health conditions, medications and the quality of the supplement. When choosing a supplement, seek advice from a registered dietitian or other health care practitioner.

What works for one person may not work for another. The only way to tell if a certain regiment is working is to have your vitamin D levels measured and then occasionally monitor.

Find the original article on WellnessFX.

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