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Taking vitamin D, along with calcium supplements, may reduce your risk of breaking a bone, but there's not yet enough evidence to say whether it may lower your risk of cancer, a new analysis concludes.
People who were taking vitamin D and calcium supplements were 11 percent less likely to fracture a bone than people not taking the supplements, according to the study.
There was an even larger reduction in fractures — about 30 percent — among elderly people living in institutions who were taking vitamin D, said study researcher Mei Chung, a nutritional epidemiologist and assistant director of the evidence-based-practice center at Tufts Medical Center.
Chung's analysis was requested by the U.S. Preventive Services Task Force, and was the only study the group requested be done in advance of their draft statement on recommendations for vitamin D intake, set to be issued in January, she said.
As to the studies examining the vitamin's role in cancer prevention, "We just don't have good enough information," Chung said, and factors such as how much vitamin D people were getting in their diets, and how much sun exposure they got were not well-controlled in the previous studies she reviewed for her analysis.
The results of the new study are published online today (Dec. 19) in the journal Annals of Internal Medicine.
Vitamin D in the body
Vitamin D is present in very few foods, though some foods are fortified with it, according to the National institutes of Health. Fish such as salmon and tuna, and egg yolks are good sources of it. It's also synthesized by the skin when we're exposed to ultraviolet rays in sunlight.
Research has shown that vitamin D is involved with the depositing of mineral in bone, Chung said, but its potential role in cancer is less clear. Some research has suggested it may promote cell division and other processes that may lead to cancer, but other work has shown it may have the opposite effect, she said. The vitamin's effect of the vitamin may vary across different parts of the body — it could promote some cancers, but inhibit the development of others.
Chung's analysis included 19 studies examining the effects of vitamin D on bone fractures, and 28 studies of its effects on cancer.
In terms of reducing fractures, vitamin D only reduced the risk when taken in conjunction with calcium, the study showed. The benefit was seen among people taking from 300 International Units (IU) to 1,100 IU daily, according to the study.
The studies she examined conflicted in their findings about whether vitamin D might prevent cancer, Chung said. Three of the studies were prospective randomized controlled trials — considered the strongest type of scientific evidence, in which participants are divided into two groups at the study's start and asked to either take vitamin D or a placebo — and these studies suggested that high doses of vitamin D (1,000 IU a day) may reduce cancer.
However, the levels of vitamin D in the blood of participants in those studies were not measured, Chung said, and without such measurements, conclusions cannot be drawn. Some people in the placebo group may have in fact been taking vitamin D supplements, perhaps as part of a multivitamin, and study participants could vary greatly in terms of the levels of vitamin D in their diets, and their sun exposure.
Some of the prospective, observational studies Chung analyzed — in which researchers did measure blood levels of vitamin D, and tracked those levels with cancer cases — suggested that people with higher levels may have a lower risk of colorectal cancer, but also showed that higher vitamin D levels brought an increased risk of having any type of cancer in general. Therefore, a general conclusion about vitamin D and cancer risk could not be made, she said.
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20 Comments
Add CommentI believe that my dad's pancreatic cancer was caused by high aspirin doses . He took it for his back pain. His back pain likely was related to shingles. A bad case of shingle can be related to a VIT D deficiency.I know that he was vit D deficient even without a test .
Reply | Report Abuse | Link to thisI don't know where you're getting this from, but there's nothing in the published medical research to support claims of a link between vitamin D deficiency and shingles. Shingles is caused by a virus, Varicella zoster (formerly known as Herpes zoster), the same one that causes chickenpox. And studies have actually shown that aspirin may PROTECT against cancer, including pancreatic cancer (see http://www.ncbi.nlm.nih.gov/pubmed/21803981)
Reply | Report Abuse | Link to thisI have shingles for the last 6 months . I take up to 20,000 i u a day in the winter. My shingles is mild....so far (with no pharma). Why would I believe a government study.
Reply | Report Abuse | Link to thishttp://articles.mercola.com/sites/articles/archive/2011/05/25/this-common-otc-painkiller-found-linked-to-cancer.aspx
Reply | Report Abuse | Link to thisAnother crap study which uses small doses of Vit D to come to completely false conclusions.
Reply | Report Abuse | Link to thisThey call 1,000 IU a "high dose"- it would be laughable if it weren't so serious!
Health professionals who use natural treatments, recommend a daily dose of Vit D of
5,000 to 10,000 IU per day.
No wonder this "study" finds that the Vit D role in
cancer prevention remains "unclear"!
I agree with Jamie Oz. 1000 IU is not a high dose. In fact there are many more studies than credited in the article. Similar low dose-studies (that were erroneously labelled as high-dose studies) have been done concerning the effects of vitamins, such as B. I took a really high dose of B6 (pyridoxine) for 20 years daily = 3 times 300 mgs per day, and I still live without the neurological damage conventional medicine would predict. I felt, in fact, much better. And I am not alone. A close friend did the same. As for vitamin D I take daily 4000 IU, but I may go up to 6000 IU any day now. In addition to the cancer problem there is evidence that vitamin D prevents influenza and other viral infections, which for some reason plague us mostly during the darker season. That vitamin D +calcium is a good thing against breaking a leg has been known for so long that this article seems pathetic.
Reply | Report Abuse | Link to thisI've never seen a good rebuttal of the Creighton University study. It was a prospective study, randomized cohort of post-menopausal women. From the Creighton website, "The four-year, randomized study followed 1,179 healthy, postmenopausal women from [six counties in] rural eastern Nebraska. Participants taking calcium, as well as a quantity of vitamin D3 nearly three times the U.S. government’s Recommended Daily Amount (RDA) for middle-age adults, showed a dramatic 60 percent or greater reduction in cancer risk than women who did not get the vitamin."
Reply | Report Abuse | Link to thisThink about it! This study says that over a four year period three out of five cancers in the Vitamin D group never happened!
Even more dramatically the report points out, "On the premise that some women entered the study with undiagnosed cancers, researchers then eliminated the first-year results and looked at the last three years of the study. When they did that, the results became even more dramatic with the calcium/vitamin D3 group showing a startling 77 percent cancer-risk reduction." (i.e., three out of four cancers didn't occur!)
Go to grassrootshealth.org for more similar studies (associated with UCSD).
It seems that possibly something important was observed here.
yes, this is a BS study and report. 1000iu is not a high dose, and 30 minutes of full body exposure around noon time in Florida where I live will produce about 10,000 iu or more. There is a good reason why exposure to the sun produces that much, and as ancient people we were exposed much more. I have taken 10,000 iu for several years and my blood tests put me around 80 ng/ml, way way below toxicity levels of 125-150 ng/ml. Check mercola.com and lef.org and vitamindcouncil.org for better info.
Reply | Report Abuse | Link to this
Reply | Report Abuse | Link to this1)If you had bothered to read the information I linked to, you would have noticed that the research was conducted by the Mayo Clinic, not the government.
2)The site you linked to is about a supposed connection between ACETOMINOPHEN and cancer, not ASPIRIN. Big difference.
and 3)Dr. Mercola is a quack and who makes unsubstantiated claims that - at best - border on criminal:
http://www.quackwatch.com/11Ind/mercola.html
I expect he'll be on his way to jail before much longer.
(also @ Andira & drchiptravis)
Reply | Report Abuse | Link to thisThe USRDAs for Vitamin D & the B vitamins are what they are for a reason. These are water-soluble vitamins, which means that anything you take in that's over what your body can use is excreted in your urine. You're all literally pissing your money away!
Don't believe vitamin D is water soluble. C and B vitamins are. Vitamins D and A are fat soluble and therefore can be toxic if too much is taken. (if water soluble, how can serum levels build up over many months?) However, the lower limit for long term toxicity appears to be greater than 20,000 IU for Vit D. Read the major data collection study done by grassrootshealth.org and studies by Reinhold Veith. Somewhere between 20,000 and 40,000/day seems to be the point at which reversible toxicity can, but doesn't always, begin.
Reply | Report Abuse | Link to this"Don't believe vitamin D is water soluble."
Reply | Report Abuse | Link to thisYou are correct. My mistake on that one. But according to the docs at the Mayo clinic (http://www.mayoclinic.com/health/vitamin-d-toxicity/AN02008), toxicity risks start at doses as low as 4,000IU/day, not 40,000. It should be noted, however, that the risk of toxicity only applies to vitamin D obtained through supplements - the body has feedback mechanisms to prevent toxicity from food and/or sunlight.
Taking megadoses of B vitamins, while harmless, is still a big watse of money.
Just googled Mayo clinic and vitamin D toxicity to see where you were coming from. Your source appears to be a nutritionist, a licensed dietician, who wrote:
Reply | Report Abuse | Link to this"The main consequence of vitamin D toxicity is a buildup of calcium in your blood (hypercalcemia), causing symptoms such as:
Vomiting
Polyuria (frequent urination)
Weight loss
Poor appetite
Constipation
Weakness
Heart rhythm abnormalities
Kidney stones
Treatment of vitamin D toxicity includes stopping vitamin D supplements and restricting calcium intake, as well as taking medication. In severe cases, hospitalization may be necessary.
Supplements can be a reasonable way to meet recommended levels — as long as you pay attention to how much you take. The recommended daily allowance of vitamin D is 600 international units (IU) for children and most adults. The recommendation for adults over age 70 is 800 IU daily. Above 4,000 IU a day the risk of adverse effects increases."
The last statement is simply unsupported pablum! It is not substantiated by any data whatsoever. By contrast, read "Vitamin D supplementation 25-hydroxyvitamin D concentrations and safety" by Reinhold Vieth, published in the Amer J Clin Nutr 1999, 69:842-56. This is a summary of the entire state (as of 1999) of Vitamin D research, complete with 135 references. It is a very scholarly work. In it, Vieth summarizes dose vs. circulating vitamin D levels, showing graphically the results of numerous authors. Figure 2 shows, with the exception of a single outlier, daily doses of up to 20,000 IU do not produce serum levels above 100 ng/ml, and since that is a naturally occurring level from sunlight alone AND no adverse effects have ever been documented at that level, it is reasonable to say that dosage is not a problem. (the outlier involved a single monthly dose of 300,000IU, reported as 10,000IU/day. Oh!)
Dr. Vieth also points out studies show that the amount of Vitamin D produced per unit dose of UVB declines as serum levels increase. This response is the same whether serum levels increase from sun or from supplements. this strongly suggests that the body does not distinguish between sun and supplements, and I'd suggest you try to track down the basis for claiming they are different. A lot of work has gone in to establishing equivalency.
Go to MSSociety.ca websites and read the studies linking low levels of Vit D in mothers with increased risk of developing Multiple sclerosis in their children. In fact there is no Vit D in breast milk unless mother is taking 4000 IU per day either through sunlight or supplement. 4000 IU in te mother means 400 IU for the breastfeeding infant.
Reply | Report Abuse | Link to thisSee the Website for the Canadian Pediatric Society.
Low levels of Vitamin D linked to increased risk of developing Type I diabetes.
Interesting article recently on BBC news linking increased risk of Chicken pox with low Vit D. Noted that increasing risk of chicken pox in India of all places because of air pollution (ozone blocks UVB rays at ground level not just in the stratosphere.)
The Mayo Clinic wouldn't have its reputation as one of the finest medical fiacilties in the world if it employed staff who spouted "unsupported pablum".
Reply | Report Abuse | Link to thisOn the other hand, Dr. Veith's introductory statements about the Vitamin D levels of prehistoric humans clearly ARE unsupported pablum - pure speculation. Whe I saw that I immediately suspected that I was about to ready some shoddy work. And I was right. Much of his condclusions are based on patient-supplied ancedotal reports (now 3rd-hand reports, since Veith is reviewing others' research)of their sun exposure and supplement intake in uncontrolled settings. It included unasubstantiated assumptions like "The highest individual serum 25(OH)D concentration obtained from sunshine was 225 nmol/L (23); in a farmer in Puerto Rico—there is no reason to think that he was taking a vitamin D supplement."
Additionally, most of the studies he references for high-dose supplementation appear to have been of short duration (1-3 months). (His entries on the Davies and Stamp at the bottom of Table 4 are so disorganized as to be unreadable - it's impossible to be sure which entries belong in which column.) Since Vitamin D is - as you pointed out - fat-soluble, any excess will be stored in the liver, where it could build up over time to toxic levels.
The "gold standard" for medical research is the long-term controlled, double-blind study. Present a well-documented one of those that supports the safety and efficacy of megadoses and I'll take it seriously. What you've provided so far is junk.
For support no the non-pablum see: http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx
Reply | Report Abuse | Link to this4000IU/day was established by the Institute of Medicine (part of the national Academy of Sciences) as the Upper Intake Level after a study commissioned by the US & Canadian governments.
As one critique of the IOM REPORT stated:
Reply | Report Abuse | Link to thisIn their review of the scientific studies the IOM panel concluded that the evidence supported a role for vitamin D exclusively in bone health. The vast body of new research supporting the health benefits of vitamin D for a reduction in the incidence of various cancers, cardiovascular disease, hypertension, diabetes, metabolic syndrome, falls, immune response, autoimmune disease, and the like were deemed inconclusive and unreliable. Thus, the IOM panel chose to base its new vitamin D reference intake solely on their evaluation of the role that vitamin D plays in bone health.
This is an unfortunate misstep for several reasons. Most importantly, it flies in the face of mounting documentation of multiple, life-supporting health benefits of higher vitamin D levels. A colorful graphic representation of these data (see www.grassrootshealth.net) has been compiled by distinguished vitamin D scientists Drs. Cedric Garland and Carole Baggerly.
Secondly, dismissing the new non-bone vitamin D research allowed the IOM to set a much lower apparent level of adequacy. Numerous studies on cancers, heart disease, diabetes, multiple sclerosis, and other diseases clearly indicate that vitamin D levels higher than the minimum required for basic bone health are needed. In fact, a panel of 41 expert vitamin D researchers and medical practitioners has set the evidence-based vitamin D target level at 40–60 ng/mL. We at the Center for Better Bones concur with the target level.
To summarize, the IOM said it could make no evaluation of non-bone benefits and then concluded a low level is adequate because they believe bone benefits are met by that low level. This is illogical in the extreme. After restricting themselves so narrowly the only logical conclusion is that they can make no statement about adequate levels of intake.
Setting a "no-harm level" is far different than suggesting harm occurs above that level. No harm level says only "we know this to be safe. Above this we don't feel as confident." The reality is there is still no evidence of harm for 10-20,000IU.
I'm curious, do you seriously doubt that naturally (sun exposure) occurring levels of vitamin D reach 80 ng/ml (200 nm/L)? Do you doubt the studies that show short sun exposures (one hour) can produce the equivalent of 10-20,000 IU? It seems to me one has to reject those ideas in order to believe more than 4000 IU is harmful.
Reply | Report Abuse | Link to thisReinhold Veith is a PhD scientist specializing in Vitamin D. Correct me if I'm wrong, but the last time I checked, licensed dietitian is not in the same league.
"The vast body of new research supporting the health benefits of vitamin D..."
Reply | Report Abuse | Link to thisWhen I search PubMed for articles about vitamin D & the conditions you mentioned, I find several that suggest correlation between low vitamin D and illness, but none clearly demonstrating CAUSATION. I do, however, find a paper implicating HIGH vitamin D in rheumatoid arthritis: http://www.ncbi.nlm.nih.gov/pubmed/22190273.
And another that SUGGESTS vitamin d supplementation may slightly decrease colorectal cancer risk, but had no impact on prostate or breast cancer and INCREASED the risk of kidney stones: http://www.ncbi.nlm.nih.gov/pubmed/22184690.
Additionally, the great majority of studies conducted on the hypothetical benefits of vitamin D beyond bone health have been conducted among the institutionalized elderly and can't necessarily be applied to the general population.
Excessive exposure to our main natural source of vitamin D - the sun - has been known for years to CAUSE melanoma, which makes vitamin D's role as a cancer preventer rather suspect.
Vitamin D's bone-health benefits have been well-documented, as have the levels needed to obtain these benefots. But it's still very far from clear whether the potential benefits of megadoses outweigh the risks. Unless/until more conclusive eveidence is found, the IOM is entirely correct to be conservative.
Regarding Dr. Veith's work, as I said before, short-term data for megadoses cannot be used to infer long-term safety. And the letters after a person's name do not guarantee academic diligence or integrity. Andrew Wakefield had a PhD and an MD after his, but that didn't stop him from making fraudulent claims that MMR vaccines caused autism.
"We at the Center for Better Bones concur with the target level."
Reply | Report Abuse | Link to thisOf course you do, because you're SELLING SOMETHING. And people won't shell out the $169.50-209.00 starter price unless you can make them believe they need it.
http://www.womentowomen.com/programs/bonehealth/default.aspx