without a vitamin D blood test you can not know how your level is at the moment, and therefore you also can't know how much to take. it's that simple. see here: http://www.vitamindcouncil.org/health/deficiency/am-i-vitamin-d-deficient.shtml

I think it might be important to add, that according to the Vitamin D Council, Vitamin D on it's own might actually cause some problems, as there some co-factors that play an important role.

Vitamin D has co-factors that the body needs in order to utilize vitamin D properly. They are: magnesium, zinc, vitamin K2, boron, a tiny amount of vitamin A. Magnesium is the most important of these co-factors. In fact, it is common for rising vitamin D levels to exacerbate an underlying magnesium deficiency. If one is having problems supplementing with vitamin D, a magnesium deficiency could be the reason why.

I take 5,000 iU per day and my levels are still just fine. Here's a good write-up: http://www.proteinpower.com/drmike/supplements/sunshine-superman/

It's tough to "OD" on D3...claims of the danger of that are extremely exaggerated.

You want the 25-hydroxy vitamin D test, I believe, to check your levels.

I think 4k IU is generally safe for most applications

"my chiropractor suggested I take 35/IU per pound?" Uhh....does he read what we read or does he follow old outdated studies and conventional wisdom?

I've seen recommendations as high as 10,000 IU per day. Dr. William Davis recommends dosages to bring your 25-hydroxy blood level up to 60 - 70 ng / (deciliter?), whatever the unit.

http://heartscanblog.blogspot.com/

grassroots.org has a cheap test as well.

most docs order D these days per patient demand/requests because of the raised awareness.

contraindications to vitamin D supplementation include: --sarcodoisis (trevor marshall is correct on this one -- errant transformed cells will produce their own sources of vitamin D and 1,25OHD -- which can be tested as well) --elevated 25OHD or elevated 1,25OHD

good resources here: http://www.grassrootshealth.net/documentation

vitamin D improves athletic performance via a variety of mechanisms and the Russians took advantage of this by putting their athletes on UV light boxes during the winter months!

vitamin D raises steroidogenesis b/c it's a cholesterol derivative...

here is a good wall street discussion for URI/flu protection today (THANK YOU GOD FOR SOME REASONABLE MAINSTREAM) despite recent institue of medicine retardness... http://online.wsj.com/article/SB10001424052748704156304576003531437073192.html?KEYWORDS=flu+vitamin+d#printMode

Can Vitamin D Replace Flu Shots?
By LAURA JOHANNES Vitamin D, long known for its beneficial effect on bones, is increasingly being studied to see if it helps prevent colds and flus. Based on early research results, some doctors are recommending high doses to help stave off the upper respiratory infections, with some even speculating it could be a substitute to the annual flu shot. But while it's well established that vitamin D boosts the immune system, many scientists say so far there's insufficient evidence that taking it will help keep a cold or flu away.

Until recently, scientists have blamed the higher prevalence of flu cases during winter to the tendency of humans to congregate inside or the low humidity of cold weather, which makes viruses survive in the air longer. Increasingly, scientists are exploring another possible explanation: During the wintertime, we are outside less, resulting in lower vitamin D absorption from the sun.

"Unless you are out there in the sun all the time, which hardly anyone is doing in wintertime, it's impossible to get enough," says James R. Sabetta, director of infectious diseases at Greenwich Hospital in Greenwich, Conn., who has studied the effect of vitamin D on respiratory infections.

Vitamin D is naturally present in few foods, such as salmon and herring, so humans need to get it either from sunlight or dietary supplements. In a recent report, the Institute of Medicine tripled the amount of vitamin D recommended for most Americans to 600 international units a day. The IOM is an arm of the National Academy of Sciences, which sets government nutrient levels.

But, based in part on early evidence that vitamin D helps prevent upper respiratory infections, some scientists recommend daily levels of 2,000 to 4,000 IUs or even higher. The Vitamin D Council, a nonprofit scientist group supported by vitamin makers and other commercial interests, recommends 5,000 IUs daily—but warns that this dose doesn't replace the conventional recommendation of a flu shot. "I recommend vitamin D and a flu shot to cover all your bases," says the council's executive director John Cannell.

It's true that basic science shows that vitamin D boosts innate immunity, or the body's first line of defense against pathogens, says Pennsylvania State University scientist A. Catharine Ross, chairman of the IOM committee that made the latest recommendations. But the recommended increase was based on vitamin D's proven positive role in bone health, she says. The panel reviewed the studies and found "no strong evidence that supports the idea that increased levels of vitamin D are going to be protective" against upper respiratory infections, she adds.

Vitamin D boosts immunity by stimulating production of cathelicidin, an antimicrobial protein that serves as a "natural antibiotic" in the body, says Michael Zasloff, a professor of surgery and pediatrics at Georgetown University Medical Center in Washington, D.C.

But so far studies looking directly at whether higher vitamin D levels help prevent upper respiratory infections have had mixed results. A Japanese study of 167 schoolchildren first published online in March in the American Journal of Clinical Nutrition, found that vitamin D supplements helped reduced incidences of influenza A but not influenza B.

Influenza A and B are the two main types of flu viruses responsible for seasonal flu epidemics every year, according to the Centers for Disease Control and Prevention. Swine and bird flus are specific subtypes of influenza A.

In an observational study published in June, Dr. Sabetta and colleagues followed 195 people during winter and found that people with a blood serum concentration of 38 nanograms per milliliter of vitamin D had half the risk of getting an upper respiratory tract infection as those with levels below that threshold. The people with higher vitamin D levels hadn't gotten any more flu shots and weren't taking more of other vitamins than those with lower levels, according to the study. The study, however, didn't rule out the possibility that the group with higher vitamin D also had better overall nutrition.

"We're very confident and we think this is going to be verified" by other studies, says Dr. Sabetta, an associate clinical professor at Yale University School of Medicine.

A 167-person study by researchers at Winthrop University Hospital in Mineola, N.Y., puts something of a dent in the vitamin D claims. The study found people taking 2,000 IUs a day of vitamin D got about the same number of upper respiratory infections as a group who got a placebo during the three-month flu season.

If vitamin D has a small positive effect, a large randomized trial will be needed to see it, says author John Aloia, chief academic officer at Winthrop University Hospital. "We found no evidence that vitamin D was protective," he says. It's also possible that it's necessary to start taking vitamin D several months before flu season to build up levels in advance, he adds.

Vitamin D is generally safe, but in high doses scientists say it can pull calcium from bones, causing kidney problems and heart disease. The IOM report says vitamin D may be toxic if you take more than 10,000 IUs a day, and warns the risk of harm may begin to increase at 4,000 IUs daily.

Write to Laura Johannes at laura.johannes@wsj.com

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