All you need to make the Vitamin D you need: Sunshine on bare skin.
"Everybody's low in Juneau - unless they're eating salmon a couple of times a day or they've been off somewhere sunny," said Justine Emerson, a family nurse practitioner at the Valley Medical Clinic in Salmon Creek.
Emerson has given several talks this year to tell people about the accumulating evidence of Vitamin D's importance. And the likelihood that they're deficient.
Emerson and other health providers say it's no cure-all.
"If we all take Vitamin D, will we not have breast cancer? Nobody's going to say it's that black and white," said Carolyn Brown, a Juneau physician. "There are so many environmental things that go into that. You have to plug in the rest of a person's life."
Nonetheless, Brown and Emerson present an array of health problems that may be prevented with the help of Vitamin D, which regulates more than 2,000 genes, helps you absorb minerals like calcium and phosphorus for healthy bones and blood, regulates normal cell development, promotes blood sugar regulation, and bolsters your immune system.
"It really is amazing," Emerson said.
A sampling of diseases for which risk is associated with low Vitamin D levels include: osteoporosis, multiple sclerosis, psoriasis, rheumatoid arthritis and Type I diabetes in children, along with a host of other autoimmune disorders.
Cancers linked to D deficiency include: breast, colon, prostate, lung, pancreatic, ovarian, Hodgkin's lymphom, non-Hodgkin's lymphoma, bladder, esophageal and uterine.
Rickets, a children's disease of soft, painful bones is caused by D deficiency. That's how D was discovered - when a Polish physician learned that mere sunbathing cured rickets.
Lack of Vitamin D also has been linked to depression, of the seasonal-affective variety.
Brown said that some of her patients upped their Vitamin D intake and ended up spending less time staring at light boxes and cutting down on antidepressants.
"The night didn't bother them," she said.
Vitamin D deficiency really picked up in Europe and America around the time of the Industrial Revolution at the end of the 18th century. People moved to cities with thick air and started spending more time inside.
That's still the case: The average adult, said one study, is indoors 93 percent of the time. Sunscreen, clothes and window glass all block the ultraviolet-B rays that cause humans to synthesize Vitamin D.
Not that it matters this far north. A Norway study showed people only produced Vitamin D with exposure to the sun from 11 a.m. to 4 p.m. April to September. Another study in Boston showed people didn't make any Vitamin D from November to mid-March.
The government set an upper limit of 1,000 IU a day for infants and 2,000 IU for everyone else in 1997, which more and more studies are beginning to suggest is low.
Overdosing is hard to do, whether naturally or by pill. An adult might make 10,000 to 20,000 IU in enough sunshine to turn light skin pink.
How to get it
Milk has been supplemented with Vitamin D since the 1940s. But one Boston University study sampled 79 brands of millk and found one-third of them had less than 5 percent of the Vitamin D per cup they claimed. Fatty fish and eggs are it for natural food sources of D, at about 350 and 20 IUs each per serving, respectively.
Emerson said in this town, people should consider taking a supplement.
But the news media seem to love to bill a single substance as the latest miracle. For years, people considered Vitamin C a cold curative. Decades later, the evidence didn't look so strong. Is this just a fad?
Look it up, said Brown - carefully.
"Don't just go Google 'Vitamin D,'" she said. "You'll get some good stuff from the NIH (National Institutes of Health), but you'll also get garbage from Snake Oil Inc. ... Be vigilant and look for credible sources."
Contact reporter Kate Golden at 523-2276 or firstname.lastname@example.org.