I have mentioned before the current fad in vitamin D related papers in the medical literature. It's also broken into the pop culture Zeitgeist as well, I regularly get forwards on the topic. Here is a Google Trends chart for the United States:
The history of medicine is, unfortunately, rather similar to the history of astrology. In fact for much of history doctors are likely to have increased, rather than decreased, mortality, thanks to an ignorance of germ theory and false paradigms such as Humorism. The demand-side pressures for cures & prevention seems to still exert a powerful push toward the rise & fall of fads (see google trends for "low carb" for example). A difference between pre-modern and contemporary fads though is that they're not all capricious today. Unfortunately though medicine is still complex, and the demand-side pressures often require an Answer. You have rafts of correlational studies, with each correlation adding to a positive feedback loop until the fad crests, and a new "it-cure" emerges on the scene (and no surprise that the beer industry is supposedly behind some of the studies which show that drinking in moderation is correlated with greater life expectancy).
All this is why papers like this are important, Vitamin D controls T cell antigen receptor signaling and activation of human T cells:
Phospholipase C (PLC) isozymes are key signaling proteins downstream of many extracellular stimuli. Here we show that naive human T cells had very low expression of PLC-γ1 and that this correlated with low T cell antigen receptor (TCR) responsiveness in naive T cells. However, TCR triggering led to an upregulation of ~75-fold in PLC-γ1 expression, which correlated with greater TCR responsiveness. Induction of PLC-γ1 was dependent on vitamin D and expression of the vitamin D receptor (VDR).Naive T cells did not express VDR, but VDR expression was induced by TCR signaling via the alternative mitogen-activated protein kinase p38 pathway. Thus, initial TCR signaling via p38 leads to successive induction of VDR and PLC-γ1, which are required for subsequent classical TCR signaling and T cell activation.
ScienceDaily has a good summary. This schematic represents the biochemical steps:
Update: Another datum that vitamin D is "hot," already retweeted 10 times in 2 hours.
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Never underestimate the power of epidemiology. Epidemiology pointed out the relationship between latitude and illness of many types (eg cancer, MS) many years ago. However, it has taken until now for scientists to go looking for the reason. The problem with the fad is that trials that were not designed specifically for the study of vitamin d are publishing data that is suspect, due to poor design. We are also seeing work published for vitamin d supplementation so low that it can have no effect.
I think it was Roy Porter (historian of medicine) who wrote that it wasn't until circa 1900 that doctors were finally saving more people than they destroyed. That's a lot of centuries of doing damage.
"publishing data that is suspect, due to poor design"
Probably worse than that outright criminal intervention by Pharma and Physcians who like their current income levels!
Just look at the latest US Gov study which uses 2,000 IU/D3/day, when 4,000 IU [depending on weight and body fat] is minimum repeletion dosage.
20,000 IU per day is normally UV-B created by outdoor farmers/field hands and lifeguard. Numerous studies done 15 years ago.
Vit D3 is not linear and the body fat must be saturated before the circulating levels can do much good
Designed To Fail from the onset.
Always look at the dosage before trusting any part of a negative Vitamin D3 study!
What needs to be made especially clear is that "vitamin" D is not a vitamin at all. Metabolized "vitamin" D becomes the steroid hormone calcitriol. Comparisons to the previous alphabetical vitamin pantheon flameouts are invalid and should never enter the discussion.
To call vitamin D research a "fad" is to fundamentally miss the boat. We are talking about a steroid hormone that plays the decisive role in everything from fertility to practically all known causes of premature death. Vitamin D receptors are found in EVERY cell. Seems to me if we are "few quarts low" we are going to blow up the engine and all moving parts...sooner than later.
Fortunately not one scintilla of vitamin D research has ever been refuted. This includes the almost nonstop reports of miraculous revelations. In the end the modern world's inability to extirpate all of the biggest killers will ultimately is resolved when it is learned that most, If not all, are diseases of vitamin D deficiency.
Read the body of evidence as have some and rethink the word âfadâ.
Fortunately not one scintilla of vitamin D research has ever been refuted.
This makes vitamin D research unique in the entire history of science back to Thales. This is big. Someone should write a book or something.
Note also that VItamin D is toxic. A gram taken in a single dose would be fatal, and excess vitamin D isn't immediately excreted like vitamin C, so with continued overuse it can build up to toxic levels.
Google this: A male patient was admitted to the Dept. of Pediatrics of the Cook County Hospital because of nausea, vomiting, weight loss, and abdominal pain. Anorexia began three weeks prior to admission, followed by vomiting which was associated with vague intermittent abdominal pain. During the week prior to admission, he started to have severe nausea with frequent vomiting and was unable to attend school. He lost 11 pounds of weight during this period. Muscle weakness and frequency of urination were noted. The childâs 35 year old mother was admitted simultaneously, with severe abdominal pain, anorexia, vomiting, and weight loss of two weeksâ duration. The patient was thin, moderately dehydrated, and appeared chronically ill.
Vitamin D poisoning.
I remain unexcited. Remember when vitamin E was the big thing, C, beta-carotene? Year after year another bogus magic cure. Maybe D will pan out. Maybe, like beta carotene it will actually turn out to be harmful.
I'm just wondering where I can get a gram of vitamin D. I have someone in mind. Surely no court would convict someone who went a little overboard on his health kick.
"Vitamin D is toxic" is a bit of a straw man, so is water at a high enough dose.
Maybe vitamin D should be licensed as a controlled medicine - it's certainly a concern when one hears of people taking 50,000 IU/d - but then maybe the authorities should work harder to determine better dosing advice, other than an RDA of 400 IU or a maximum of 2,000 IU/d both of which are unhelpful.
Of more concern, and not often reported, is that vitamin D levels above 50-60 ng/ml may increase the risk of mortality (1).
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1. Melamed, M. L., Michos, E. D., Post, W. & Astor, B. 25-hydroxyvitamin d levels and the risk of mortality in the general population. Archives of internal medicine 168, 1629-1637 (2008). URL http://dx.doi.org/10.1001/archinte.168.15.1629.
"Vitamin D is toxic" is a bit of a straw man; water is toxic at a high enough dose.
Maybe vitamin D should be licensed as a controlled medicine - it's certainly a concern when one hears of people taking 50,000 IU/d - but then maybe the authorities should work harder to determine better dosing advice, other than an RDA of 400 IU or a maximum of 2,000 IU/d both of which are unhelpful.
Vitamin D is a steroid? Will this hurt my NFL chances? I need to stay clean.
That was quick - an RCT that demonstrates the T-cell / vitamin D link in action:
Urashima, M. et al. Randomized trial of vitamin d supplementation to prevent seasonal influenza a in schoolchildren. The American journal of clinical nutrition (2010). URL http://dx.doi.org/10.3945/ajcn.2009.29094.
Mills: The Institute of Medicine is currently evaluating the daily required intake (DRI) and tolerable upper intake limit (TUIL) for vitamin D. Currently the DRI is 400 IU for middle age adults and the TUIL for all is 2000 IU. They will announce the new level in May 2010. If history is any indication, they will grossly understate the need for vitamin D like they did in 1997.
John Emerson: Yes, a gram is toxic. Even a milligram taken every day for a year is likely to cause harm. That's 40,000 IU or about half a bottle of vitamin D pills. I don't know anyone dumb enough to take half a bottle of pills every day for a year. If rare accidental overdoses cause harm, that doesn't negate the health-giving properties of smart dosages. That would be like outlawing golf because Tiger Woods' wife used a golf club as a weapon.
John, regading the steroid issue, calcitriol, the active form of vitamin D, is the most potent steroid hormone known. It is believed to affect about 10 percent of the body's 23,000 genes although the real number varies person to person. If people really understood the positive effect of having a blood level over 50 ng/mL everybody everywhere would do it. There is no credible counter-argument. Good luck in your NFL testing.
Tom Bri: Your critism is a logical fallacy called "guilt by association". Your argument is less than compelling.
Kevin Gelling: Your suggestion that 50-60 ng/mL blood level may increase mortality is clearly wrong, except for a miniscule fraction of the population with rare sensitivity. Every expert who has been studying vitamin D for decades says your chances of mortality drops sharply if you have that blood level. Further, your suggestion to make vitamin D a controlled substance tells me you favor public policy that ensures a steady stream of sick and dying patients to feed the 2 trillion dollar per year US medical industry.
For the record, I take 11,000 IU a day and have a blood level 55 ng/mL. Kevin, according to you, I should be dead by now, however I firmly believe I will outlive you by a wide margin. I hope I get invited to your funeral so I can tell the greiving group what I think of you and your ideas.