Thursday, January 20, 2011

What's The Real Deal On Vitamin D?

What are the myths and facts surrounding this "miracle" vitamin? Is it too good to be true? Is its reputation all hype and no substance?
Vitamin D surprisingly is not only a vitamin but classified as a steroid hormone, - a fat-soluble hormone! When vitamin D is in your body, it's called 1.25 dihydroxy vitamin D which starts when your skin is exposed to ultraviolet light, then manufactured into 7 dehydrocholesterol by reacting with cholesterol.
Then, it will be absorbed by the gastro intestinal tract and enters the blood stream through the liver. It is then mixed with calcium to help bones and then expelled through the kidney. Vitamin D has a half life in the body of about 2-3 weeks.

Most people that specifically need vitamin D are infants who are breast fed because human breast milk doesn't give them vitamin D that they need, the reason why it is highly recommended that they should receive vitamin D supplementation.

The following groups may be unable to synthesize vitamin D efficiently:
  • breast fed infants
  • Americans who are 50 years old and more (as we age, the skin is less able to synthesize vitamin D efficiently as well as the kidney's ability to produce vitamin D diminishes.
  • people with limited sun exposure (like those from the northern latitudes and women who are covered from head to toe because of religious beliefs.)
  • African-Americans are at risk for vitamin D defficiency.
  • individuals with fat malabsorption (Crohn's disease, cystic fibrosis, some forms of liver diseases)
  • obese individuals or those who have undergone gastric bypass surgery.
It's good to get vitamin D from sunlight but that doesn't mean you have to go out and lie under the sun without sunscreen protection every weekend.
Some doctors recommend sunlight 10-15 minutes at least 3x a week.

Vitamin D is naturally found in very few foods. The majority of it is found in fish; - like salmon, mackerel and cod liver oil. We also get it from milk and cereal that have been fortified with nutrient.

The recommended amounts of Vitamin D for both men and women are;
  • birth to 50 yrs. - 200 IU
  • 51-70 yrs. - 400 IU
  • 71+ yrs. - 600IU
It is rare to have vitamin D toxicity, but too much of it can cause nausea, vomiting, poor appetite, weakness, constipation and weight loss. It might also raise blood calcium levels which can cause altered mental status, confusion and heart rythm abnormalities.
There are no recommended dietary allowances established, so that what might be too much for one individual may not be too much for another.

According to Deborah Kotz in the article in U.S. News & World Report in June 8, 2007, vitamin D is also believed to ward off cancer and protect against tuberculosis, diabetes, colds and the flu.
There are also evidences that vitamin D maybe useful in preventing certain types of cancer, although research is still limited.