Vitamin D for longevity, but watch the dose.

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As Vitamins Go, D, You Are My SunshineBy Sally SquiresTuesday, September 18, 2007; HE05http://www.washingt onpost.com/ wp-dyn/content/ article/2007/ 09/14/AR20070914 02124.htmlVitamin D is best known for building strong bones, but it may have anotherbenefit: longevity.In a recent analysis of more than 18 studies involving nearly 60,000people, those who took vitamin D supplements had a 7 percent reduction inmortality from all causes compared with those who didn't take the vitamin.The numbers improved slightly for people who took vitamin D for threeyears or more. They had an 8 percent lower risk of dying."The results are remarkable," notes Harvard School of Public Health'sEdward Giovannucci in an editorial published in the Archives of InternalMedicine, where the study also appeared this

month.Even better, the study found no "negative surprises" from taking vitaminD, as long as doses were kept between 300 to 2,000 international units(IU) per day.That's key because recent excitement over the health benefits of vitaminshas been tempered by sobering results: Scandinavian studies, for example,found that smokers who took beta carotene -- converted in the body tovitamin A -- had an increased risk of developing lung cancer compared withthose who didn't take the supplements.These new findings add to the growing interest in vitamin D -- oftendubbed the "sunshine vitamin" because in its natural form, the vitamin isproduced by the skin under the sun's ultraviolet rays.Beyond its proven bone benefits, vitamin D is critical for immunity,prompting production of antimicrobial substances that seem to act likenatural antibiotics and antiviral agents.Some experts think that

the reduced sun exposure during winter could helpaccount for the seasonal ebb and flow of colds and influenza. "It's alwaysbeen a mystery why influenza disappears in the summertime," notes John J.Cannell, a psychiatrist at Atascadero State Hospital in California whoheads the nonprofit Vitamin D Council.Emerging research also points to a role for vitamin D in cancerprevention, particularly against breast, colon, prostate and lung tumors.Vitamin D could help with cancer treatment. One recent study found thatlung cancer patients who either got a lot of sun or had a high intake ofvitamin D had three times the survival rate of their counterparts withlower vitamin D levels.Another possible benefit of vitamin D is prevention of Type 2 diabetes,which affects an estimated 17 million Americans. And in an upcoming paper,Cannell speculates, based on population studies, that vitamin D deficiencyduring

pregnancy may play a role in the worldwide increase of childhoodautism.So how could one vitamin have so many potentially wide-ranging effects?Unlike other vitamins, D acts both as a vitamin and as a hormone that canbe activated as needed by the body.This wider role of vitamin D has led scientists to weigh whether thecurrent recommended daily intake is high enough. In the meantime, agrowing number of experts, including Harvard's Giovannucci, advise routinemeasurement of vitamin D blood levels to detect deficiencies that aren'tsevere enough to produce clinical signs."Given the high probability of benefit, and the low likelihood of harm, itseems prudent that physicians measure" levels in their patients, hewrites.Doing that will be costly: Vitamin D testing runs at least $100 per test.There are other drawbacks, too. No optimal blood levels have been set forthe vitamin. (Unlike the

international units used to gauge intake ofvitamin D, blood levels are measured in nanograms per milliliter.)Giovannucci proposes 30 to 40 nanograms per milliliter as a "reasonabletarget."Others aren't so sure. "At the moment, it's really difficult to be able topinpoint whether a particular level can be used in all circumstances tosay this person has the best level of vitamin D that they can have," saysAnn Prentice, director of the Medical Research Council's Human NutritionResearch Laboratory in Cambridge, England. "Most of the work has been inthe disease of old age and largely in Caucasians. We really don't knowthat those levels of vitamin D would provide the same benefits in childrenand pregnant women, or in different ethnic groups. There are lots ofreasons to think that they probably wouldn't be."So for now, Prentice lets her skin produce vitamin D by having brief boutsof sun exposure

both in the U.K. and in Western Africa, where she doesresearch.But she advises her mother to take a vitamin D supplement. That's becauseher mother doesn't get much sun exposure, and with age, the skin's abilityto produce vitamin D drops significantly. Adults 65 or older make only 25percent of the vitamin D produced by those ages 20 to 30.Here's how you can make sure you get enough vitamin D:¿ Eat salmon or mackerel. Just 3.5 ounces of either provides 90 percent ofthe daily value for vitamin D. Other foods naturally rich in vitamin Dinclude sardines, tuna, eggs and liver. Foods fortified with vitamin Dinclude milk, margarine and some breakfast cereals.¿ Grab a few rays. Emphasis here is on "few," since prolonged sun exposureincreases risk of skin cancer significantly. Just 20 minutes of sunexposure without sunscreen enables the skin to produce about 20,000 IU ofvitamin D. "You'd

have to drink about 400 glasses of milk to get that sameamount," Cannell notes. And contrary to taking mega doses of dietarysupplements, it appears that sun exposure does not cause toxic levels ofvitamin D.¿ Take a vitamin D supplement. The National Academy of Sciences sets 200IU per day as the adequate intake for those 19 to 50 years old; 400 IU foradults 51 to 70; and 600 IU for those 71 or older. In the latest studythat showed the 7 percent reduction in mortality, the average intake wasabout 500 IU per day.Too much vitamin D can be toxic -- the reason the National Academy ofSciences sets 2,000 IU per day as the tolerable upper limit for adults.Multivitamins provide vitamin D, but the amount varies widely, so read thelabels: Men's One-A-Day contains 400 IU; Centrum Silver has 500 IU;Women's One-A-Day contains 800 IU; and Nature Made Multivitamins provides1,000 IU.Many calcium

supplements also contain vitamin D, providing between 200 and400 IU. And single vitamin D supplements are another option. Just makesure that the combination of dietary supplements and food sources ofvitamin D don't exceed the upper limit. Signs of toxicity, which includebone loss and kidney problems, begin at about 10,000 IU daily.View all comments that have been posted about this article.© 2007 The Washington Post Company------------ --------- --------- ---

If I came to you and said, "I'm going to perform a little sexual assault on you---a small rape---because, one day you could meet a rapist and you could be raped. But, it won't be as bad the second time as the first time." This is exactly the same thing as giving someone a vaccine, or a little bit of disease. It's nonsense! An Interview With Guylaine Lanctot, M.D. By Kenneth & Dee Burke

 

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