Sun or No Sun – The Debate Over Sun Exposure and Vitamin D

We have all been told that over-exposure to the sun is not healthy; it can cause medical problems including skin cancer. However, sun exposure is essential for the proper functioning of most living beings (except cave dwelling animals and deep sea creatures). Ironically, it is the very same ultraviolet rays which help the body produce vitamin D that can also lead to skin cancer.

The Role of Vitamin D

The major function of vitamin D is maintaining normal blood levels of calcium and phosphorus in our bodies. Vitamin D aids in the absorption of calcium which forms and maintains strong bones. If blood levels of calcium and phosphate become too low, the body produces hormones which can cause calcium and phosphates to be released from our bones. This often causes the bones to become thin, brittle, soft or even misshapen.

Vitamin D is a prohormone. It has no hormone activity itself, but is converted to an active hormone through the ultraviolet light produced by the sun. Three major forms of vitamin D are: vitamin D2 (ergocalciferol); vitamin D2 (cholecalciferol) and vitamin D3. These are made in the skin as it reacts to ultraviolet light that has an UV index greater than 3.

Getting the Right Amount of Vitamin D

The proper amount of vitamin D each day is 1,000 units. There are a variety of ways in which the body can obtain the correct daily amount. Here are some examples: food sources such as a glass of milk provide 100 units and a multivitamin provides 400 units. The remaining 500 units need to come from the ultraviolet rays of the sun.

Sunscreens can actually reduce vitamin D production by excessively restricting ultraviolet rays. Medical data on people who applied sunscreen before venturing outside shows that these people were, in fact, deficient in vitamin D by the end of the summer. The evidence shows that adults who use sunscreen and avoid direct sun exposure but drink milk and take a multivitamin supplement were still at risk of developing a vitamin D deficiency.

Vitamin D Studies

Studies continue to investigate vitamin D, nicknamed “The Sunshine Vitamin”, for all of its benefits. Four separate medical studies found that vitamin D helped protect against lymphoma, prostate, lung cancers and colon cancer. This same study also found that vitamin D also helped protect against skin cancer.

Many scientists recommend “safe sun” exposure for good health; i.e. 15 minute exposures to the sun without sunscreen a few times a week. Dr. Edward Giovannucci, Harvard University professor of medicine and nutrition stated the importance of “safe sun” in a lecture to the American Association for Cancer Research. His research shows that vitamin D could prevent 30 deaths for each one death caused by skin cancer.

American Cancer Society’s chief epidemiologist, Dr. Michael Thun states, “There is now intriguing evidence that vitamin D may have a role in the prevention as well as treatment of certain cancers.” (USATODAY.Com May 21, 2005). Still remaining, however, is the lack of consensus among scientists as to how much daily vitamin D is actually needed and what the best way is to get it.

Choices, Considerations and Risks

Supplements may seem like a great idea, however, the amount of vitamin D provided from supplements and food is just not adequate. In fact, Dr. Giovannucci states that supplements containing vitamin D may not raise the vitamin D levels in our systems very much at all, and too much of a supplement can cause a dangerous buildup of calcium in the body.

People at risk are:

  • The elderly, as their skin produces less vitamin D
  • Black people have a higher rate of cancer than whites; their greater skin pigmentation prevents the making of vitamin D
  • Obese people have lower levels of vitamin D as the vitamin gets trapped in their fat cells
  • Diabetics are prone to cancer; their kidneys have trouble converting vitamin D for the body to use
  • People who live in the northeastern or Scandinavia have higher cancer rates than those who get more sunshine year-round

It has been thirty years since the landmark discovery about vitamin D works was made. Leading scientists have since been urging people to get enough sunlight in order to make the proper amounts of vitamin D. Common sense is crucial; prolonged sunbathing or tanning salons are not advised.


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