Study: Vitamin D May Promote Brain Health
JOHN YDSTIE, host:
In a moment, we'll visit a glacier in the Himalayas that scientists are studying for signs of climate change. But first, science news from sunny California, where a new study shows how vitamin D may help promote the health of your brain.
ALLISON AUBREY: When there's more sunshine outside, it's easier to soak up those rays and make vitamin D. Researcher Joyce McCann of the Children's Hospital of Oakland's Research Institute says their home climate make give her an advantage, but there's a hitch.
Ms. JOYCE McCANN (Oakland Research Institute): We're all covered up of clothes and people like me spend a lot of the day hunched in front of our computers, and so many of us don't get enough vitamin D.
AUBREY: When sunshine is not an option, there are fortified foods or vitamin supplements. Researchers have long understood that vitamin D and calcium act as a sort of lock and key with D unlocking trapped calcium, helping it circulate around the body. Studies show that when people are deficient in D, they are more susceptible to bone fractures, and a developing body of evidence suggests deficiencies also put people at higher risk of colon cancer.
McCann's study focused on evidence linking vitamin D to brain health. She explains once D is converted in the body to its active form, calcitriol, it binds to receptors in the brain.
Ms. McCANN: The very interesting biological observation is that these vitamin D receptors are located throughout the brain. So that means that vitamin D is working in the brain.
AUBREY: Those at the highest risk of vitamin D deficiencies include people with dark skin, who don't absorb the sun's rays as quickly, and older folks.
Ms. McCANN: Because the conversion in the skin also decreases with age.
AUBREY: By age 65, there is a fourfold decrease in the ability of the skin to make vitamin D compared to 25-year-olds. So even though it's not exactly clear how a lack of D may impair the function of the brain, experts say it's prudent to supplement. Lots of foods already do, and many multivitamins now include more than two times the daily recommended dose.
Allison Aubrey, NPR News, Washington.
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