VOA标准英语2010年-Studies Find Increasing Health Benefit（在线收听）

Michael Irwig gives staff lectures on Vitamin D at George Washington University Hospital

The U.S. Institute of Medicine is involved in a study that will likely result in an increase in the recommended daily intake of vitamin D.  Research shows vitamin D affects nearly every area of the body and low levels of vitamin D can have serious consequences.

It's the vitamin associated with the sun that we absorb through our skin, and increasingly block out when we use sunblock, to avoid getting skin cancer.

Vitamin D is also available in some foods, but as the world gets fatter, Vitamin D gets trapped in body fat.

What doctors are now discovering is that many people don't have enough vitamin D.

That's why Dr. Michael Irwig gives lectures on Vitamin D to the staff at the George Washington University Hospital.

"Vitamin D has become a very hot topic in medicine now as we are discovering very high levels of vitamin D deficiency in our population, not only in the U.S., but worldwide," said Dr. Irwig.

Vitamin D helps our bodies absorb calcium and helps form and maintain strong bones.  Extreme vitamin D deficiency causes deformities in children and weak bones in adults.

Doctors rarely see these conditions.  But studies have linked vitamin D deficiency to a number of serious health problems, including heart disease, several types of cancer, osteoporosis, diabetes, Alzheimer's disease and some autoimmune disorders.

Low levels of vitamin D are even associated with high blood pressure.

"What's very interesting about vitamin D is that it's involved all throughout the body, and it's involved on a local level, so you can have vitamin D active in the breasts, in the prostate, in the colon, and it's thought that the locally-acting vitamin D is helping to protect the body against these cancers, regulating how cells grow and how cells die," added Dr. Irwig.

Doctors are also finding connections between vitamin D and pregnancy. 

"There have been some studies showing that if you give pregnant women 4,000 units of vitamin D a day, their rates of complications in pregnancy are much decreased," noted Dr. Irwig.  "If you look at things like infection, pre-term delivery, even gestational diabetes mellitus, they are all reduced with givng pregnant women higher doses of vitamin D."

The Institute of Medicine, which advises the U.S. government on health, is expected to update its recommended amount of vitamin D by September.  It currently recommends 200 to 600 units of vitamin D daily.  But many experts, including Dr. Irwig, recommend adults take 1,000 to 2,000 units a day, an amount only possible to get though supplements.