Does vitamin D protect against cancer?

The Institute of Medicine (IOM), an advisory group established by Congress, was charged by the U.S. and Canadian governments to gather the existing evidence on the health benefits of vitamin D and calcium, and come up with revised guidelines to help the public and the medical community determine the recommend dietary allowance, or RDA, of each nutrient.

The IOM stated: “That’s not to say that vitamin D will not at some point prove effective in preventing or alleviating conditions other than bone-related fractures; Dr. JoAnn Manson, committee member is currently recruiting for a multicenter study, the Vitamin D and Omega-3 Trial, or VITAL, that aims to do just that. VITAL will involve more than 20,000 healthy subjects who will be taking either vitamin D or a placebo and then followed over a number of years for their risk of developing cancer, stroke and heart disease.

VITAL will be the first such large-scale randomized study to analyze witamin D supplementation in this scientifically validated way, so until those results are released, in another five years or so, the IOM committee declined to make any recommendations about vitamin D’s role in anything other than promoting bone health.

The committee also established upper limits of intake per day, since some studies suggest that megadoses of the vitamin D may not provide any additional benefit, and may actually “cause” harm. Even when it comes to bone health, for example, a recent trial showed that high doses of vitamin D supplementation did not lower the rate of fractures and other studies showed high levels of D increased the risk of kidney stones and other renal conditions.

“This perception that more is better and that everyone should jump on the bandwagon of high doses of vitamin D is of concern until we have evidence from randomized clinical trials that the benefits of such dosing outweighs the risks,” says Manson.

The Institute of Medicine (IOM) was under the direction of the U.S. National Institutes of Health and the Food and Drug Administration to limit their review of vitamin D evidence to randomized controlled trials and nested case-control studies with several years follow up between blood draw for 25(OH)D measurement and disease outcome. Thus, they could not include in their review over 90% of the evidence that UVB and vitamin D reduce the risk of up to 100 types of disease. Results from case-control studies for breast and colon cancer indicate a strong inverse relation with respect to serum 25(OH)D level of about 40 ng/ml. Several reviews by vitamin D experts recommend 1000-2000 IU/d or more of vitamin D3 and serum 25(OH)D levels of 30-40 ng/ml. The IOM recommendations and those in the recent joint UK report
http://info.cancerresearchuk.org/prod_consump/groups/cr_common/@nre/@sun/documents/generalcontent/cr_052628.pdf
should be considered the results of bodies reluctant to endorse vitamin D since they benefit from the status quo. Those wishing to maintain optimal health will generally ignore these reports except, perhaps, the portion in the IOM report admitting that there are no adverse effects of vitamin D intakes of 10,000 IU/d.

This is interesting: Tuesday, November 30, 2010, Time Magazine reported the findings for the new guidelines for vitamin D intake anounced by the Institute of Medicine (IOM), changed from 200 IU a day to 600 IU for the average adult. The new recommendations are based on data from more than 1,000 studies.

In addition, the report states that contrary to previous claims, most Americans are not lacking in vitamin D, and that the majority of adults are in fact well-supplied with the bone-building vitamin. The discrepancy can be traced to the lack of standardization among labs that test for blood levels of the vitamin.

Different facilities establish varying thresholds for what they consider to be sufficient levels of vitamin D and that can lead to a misleading perception that more people are deficient.

The mistaken belief that Americans are deficient in vitamin D has led some experts to suggest that adults spend more time in the sun, since UV exposure can trigger vitamin D synthesis in the skin. But the committee cautions against that practice, since UV exposure can increase the risk of skin cancer and that risk outweighs the need to boost vitamin D production in the body.

The committee’s advice also applies only to nutritionl requirements to maintain skeletal health, and should not, says committe member Dr. JoAnn Manson, be interpreted to suggest benefit for any other health condition. In recent years, studies have suggested a link between vitamin D supplementation and a lower risk of heart disease, as well as prevention of cancer, Alzheimer’s, diabetes and autoimmune conditions.

But after a thorough review of the existing evidence for those diseases, the committee determined that the data on such supplementation and non-bone conditions was “inconsistent, inconclusive as to the cause and effect, and insufficient to inform nutritional requirements. Most of the data drawing these correlations did not come from rigorous clinical trials that randomly assigned subjects to a vitamin or placebo group.”

I just found out from new research that as yet there is no definitive scientific support for the new model of cancer development, the authors of the study say that maintaining adequate levels of vitamin D could potentially halt the development of cancer at its very earliest stages.

Some people argue that we all need a lot more vitamin D and that this is one of the reasons Scotland’s health is so poor

Stuart: I am emotional but not biased. I’ve been studying the evidence for nearly 27 years. I sincerely think people, like my own Mom, believe what doctors write in print and don’t question the fact that doctors are just people and not necessarily smarter than anybody. And some, like Dr. Holick, are promoting themselves, selling ridiculous books and making money from the tanning bed industry.

The credible evidence comes from organizations like The American Cancer Society, The Cancer Institute, The Mayo Clinic and of course The Skin Cancer Foundation, among others.

The Skin Cancer Foundation writes: “The latest figures confirm that skin cancer, the world’s most common cancer, is truly an epidemic. There are more new cases annually than the combined incidence of cancers of the breast, prostate, lung, and colon. While skin cancer, particularly nonmelonoma skin cancer, is usually very treatable when caught early, it should not be taken lightly. Skin cancers have a high rate of recurrence, and anyone who has had one runs an increased risk of developing another skin cancer, including melanoma. Additionally, people who have had nonmelanoma skin cancer have twice the risk of developing other malignancies, such as lung, colon, and breast cancers. Melanoma, the deadliest skin cancer, may metastasize(spread) to distant tissues or organs, and can be life-threatening, if not detected and treated quickly.”

If these organizations are not credible to you, then you are the one that is biased.

Narek

With respect, you come across as emotive and biased. Relating anecdotal “evidence and discussing friends/relatives appears out of place in scientific debate.

Steve: No disrespect, I don’t think your information is BS. My oldest son is very intelligent with a very lengthy education and has argued with me about UVR for years. He agrees with you on all acounts. I think the bottom line to this arguement is: Is vitamin D3, aquired from the sun only, superior to food or supplements? I think not! There is no evidence of that.

Why get more UVR, which is cumulative, when the safe alternative doesn’t cause cancer? Most of us have already had way too much UVR; why keep getting more?

I know for me, I would be stuck in that cancer world if I had followed the UVR route to get Vitamin D3. Once you get skin cancer, you will most certainly get more. People my age are getting cancers cut off over and over. It’s no big deal to them but I think it means they are also more likely to get other kinds of cancer.

Also, Oxygen is not on the government cancer list. The reason is obvious. And how do you know what goes on behind closed doors in Hamilton’s life? He has the money to get the best fake tan available.

I have an aunt whom was also noted for her dark tan. What most people don’t know about: she has had numerous plastic surgeries to undo the horrible damage the sun did to her skin.

Maybe I am making too big of a deal about this because most people are going to get that glorious tan like I did many years ago but I think if I can get one person to think about what I’m presenting, it’s worth it..

Narek: Let’s not fall prey to comparing UV to tobacco, arsenic, 1,2,3-Trichloropropane or any other such item listed on the HHS Report on Carcinogens. Their order of appearance (sequence) has nothing to do with their severity. More importantly… there is NO dose relationship with their inclusion on the list.

Oxygen and water are toxic in high enough dosages. We do not “need” any tobacco or arsenic for survival… but we do need UV light in appropriate dosages (J/m2 Eeff). I take 5mg of rat poison (Coumadin) every day so my artifical aortic heart valve won’t clot. It’s all about dose – not dose rate – regarding UVR or warfarin or beer or everything else in life..

Is George Hamilton in mortal danger after 60 years of tanning without burning. I don’t think so. Was Dean Martin in mortal danger (like the Marlboro man was)for 60 years of cigarettes? Of course!

I sincerely hope your dad didn’t die of internal cancer metastasized from CMM. If so I certainly understand your position re UVR. Mine died from complications of surgery for a broken hip. If we’d taken him out in the sun more as he grew old… maybe his bones would have remained stronger. Albeit he’d probably have grown some more BCC’s.

Speaking of studying UV for many years… me too. If you google (or bing or yahoo) solarmeter or uv meters you will see my website ranked #1 after the paid ads. I know exacty what nm of UVR is effective for what response… EAS weighted or unweighted.

After 20 years of attending NIST/NOAA UV instrument intercomparisons in Boulder, CO… measuring UV on the roof of NIST in Gaithersburg, MD… and working with FDA re tanning bed regulations, etc, etc, I can assure you my replies re UVR are not BS.

Steve: The average lifespan only 100 years ago was about 40 years old. Mother nature creates numerous life killing elements and occurrences, from H.I.V. to volcanos. And how many lifeguards do you know personally, to know what the sun did to them?

Being born in 1953, I know way too many people who have had skin cancers and then other cancers after the skin cancer. I just watched my Dad die a painful, horrible death from cancer at the age of 78. He was still young and was not ready to die.

He had the same attitude about the sun that you do and I honestly believe he would be alive if he had just worn a hat while in the mountains he loved so much..Good for you if you have genes that protect you from the same fate but cancer, especially skin cancer, is an epidemic.

I’ve studied about UVR for many years and I’m certain these facts about it’s dangers are not sensationalized, unlike the tanning bed industry and quacks like Dr. Michael F. Holick and Dr. Mercola.

I’ve had way too much sun and paid a big price for it. Back in 1968 my dermatologist recommended sun exposure for my acne. Now days they say it makes it worse.

People are going to believe what they want but in the end, the truth is still the truth…Did you ever wonder what happened to the Marlboro man? The cigarette companies had doctors and scientists saying that tobacco did not cause cancer. How ironic is that?

Those positions certainly sound extreme… as if they were proposed by someone with a definate anti-UV agenda. Kinda like Algore warning (7 years ago) that New York would be underwater in 7 years if we don’t stop global warming.

How cruel of mother nature to allow humans to develop and thrive directly under that poisonous sun for thousands of years with no big pharma spf lotions.

What’s wrong with lifeguards’ immune systems? Nothing. Plus they have among the highest blood levels of 25(OH)D on the planet. Why do most articles declare UVA1 as immunostimulatory – not suppressive?

This was written by the American Cancer Society: “If you live in the mid-United States, being in direct sunlight for 30 minutes creates a buildup of a lethal dose of UVR for human cells not protected by sunscreen. The only other exposure to a carcinogen approaching this level of exposure is cigarette smoke in very heavy smokers.” http://www.cancer.org/docroot/PED/content/PED_1_3X_Radiation_Exposure_and_Cancer…9/15/2009

Written by the Bulletin of the World Health Organization-Immunosuppression induced by ultraviolet radiation: relevance to public health: “It was concluded that people could receive sufficient solar UV in about 100 minutes at mid-latitudes around noon to suppress their immune responses to microbes by 50% This amount of UV exposure is experienced frequently by many individuals and therefore the effectiveness of the immune system against pathogens may be compromised as a result.” http://www.scielosp.org/scielo.php?pid=S0042-96862002001100012&script=sci_arttext 9/14/2009

Steve: The Department of Health and Human Services released their Official Citation: Report on Carcinogens, Eleventh Edition, listing “after” 1,2,3-Trichloropropane is: Ultraviolet Radiation Related Exposures, Solar Radiation, Ultraviolet A Radiation, Ultraviolet B Radiation, Ultraviolet C Radiation. Then next on the list is Urethane. http://ehis.niehs.nih.gov/

Then try The American Cancer Society, listing UVR as one of the three top cancer causers. Look up the information about the dangerous kinds of radiation like UVR and what it does to immunity. The immune system is what kills cancer cells in every human body.

George Burns lived to be 100 and smoked cigars; does that mean tobacco doesn’t cause lung cancer? You really think all of these reputable, non-profit organzations are being bought and paid for but you would trust the huge tanning bed industry and all of the cosmetic companys that make billions off of sun damage?

My concern is that lots of people everywhere are suffering and dying from this backwards logic that people choose to promote without regard to the true human cost. I’ve seen that cost firsthand and it’s nothing to be flippant about.

And by the way, Bob Marley, the famous black reggae singer, died from Melanoma at a young age.

Does anyone on this right here blog know what percentage of melanomas occur on body areas where the sun don’t shine? I’ve read anywhere from 40-60% but have never seen any definitive data from AAD, etc.

Also, please, what percentage of CMM’s occur on people with type 1 skin (always burns never tans) and type 2A (usually burns rarely tans)? It appears that every melanoma poster girl (Australia, Miss NJ, the 20/20 person, etc) are type 1 and 2A… and they experienced significant outdoor sunburns before trying a few sunbed sessions. Then they blamed the melanoma on a tanning salon (aka parlor to the press).

My father and I (type 2B German/Irish skin) have both had some BCC’s frozen or cut off over the years…. having spent an above average time boating in the sun. Dad died last year from complications of surgery unrelated to skin cancer at age 94. I’m still boating every summer with no SPF at age 65. Tsk-tsk. Shame-shame.

Anyway – back on topic… if anyone knows answers to the questions above I’d appreciate hearing back. But please don’t quote something from skincancer.org, etc because they are hopelessly conflicted by big pharma sunscreen and beauty magazine funding support as seen on below link. Thanks.

http://www.skincancer.org/cosmetic-industry-board.html

Kevan,

If sunlight wasn’t harmful, animals wouldn’t have fur and humans wouldn’t develop deadly, disfiguring skin cancers. Humans developed and evolved for many different reasons in order to survive as a species. All animals have tails, including humans, who have one for 4 weeks before being born.

The Skin Cancer foundation wrote: “The tradeoff of vitamin D production today for photoaging and skin cancer decades hence may have made sense millennia ago, when life expectancy was 40 years or less, but it’s a poor exchange when life expectancy has doubled, skin rejuvenation is a $35 billion/year industry, and one in three Caucasians develops skin cancer.”

If you really think sunlight prevents Melanoma, good luck, you’ll need it. My husband’s uncle was a farmer with a 30 year tan that prevented him from burning. He came down with Melanoma and sufferered a horrible, painful ordeal and then died. He wasn’t ready to die, he had just retired from a very hard occupation..

Skin cancer is an epidemic and sun exposure is cummulative. Once you get skin cancer, you are more likely to keep getting it. People who have skin cancer are more likely to get other cancers. And The American Cancer Society and other reputable organizations state that UVR damages immunity.

And why do doctors treat vitamin D deficiency with supplements, not sun exposure?

Narek,

Melanoma rates are increasing in indoor workers but not those who work outdoors. Glass blocks UVB light but not UVA. D3 is stored in the skin and calcitriol, the active form of vitamin D, has many anti-cancer properties.

It looks increasing likely that UVA causes melanoma and UVB curtails it. Take one away, by working indoors, or have too much UVA, by using tanning beds which have a higher percentage of UVA, and the risk of melanoma increases.

Before sunlight is abandoned, research needs to establish if vitamin D supplementation is equivalent to UVB D3 for protection against melanoma (and other morbidities) and does supplementation protect against UVA when working indoors without increased pigmentation from a summer tan?

The ‘elephant is in the room’ is that evolution selected paler skin for living at latitude. It is highly likely that skin colour is matched with the UV exposure of a location for exposure typical of a pre-modern lifestyle. If sunlight was so terrible and had no benefits then we’d all be dark-skinned.

In the past, when people covered up, Melanoma was unheard of, until vitamin D through sun exposure was discovered to prevent rickets. It sounds like you got your information from Dr. Michael F. Holick, who was bought and paid for by the tanning bed industry. His book, The UV Advantage, is full of unfounded claims. Other Drs. have jumped on the band wagon, using his data. There is no scientific proof, at this time, that UVR induced vitamin D3 is better than safe alternatives. Maybe they should add vitamin D3 to soda-pop…

In reply to Johnny Bourdeux: I don’t doubt your enthusiasm in the probability that UVB rays (which creates Vitamin D3 through the skin) helps to prevent a number of diseases, including cancer, especially in light of the fact that you have Crohn’s disease.

I “am” doubting the science you are using to prove some of these claims. What you are presenting as proof is not valid science. Much of what you are writing sounds like the rhetoric that is written in Dr. Michael F. Holick’s book, “The UV Advantage”.

Melanoma was almost unheard of when people covered up from the sun and until 20 years after vitamin D through sun exposure (which was also added to the milk) was discovered to prevent rickets, the amount of time it usually takes Melanoma to develop.

I know there are a number of other scientists claiming the same conclusions about vitamin D3 through UVB exposure but Holick and or the Garland Brothers are used as a reference in most of their research.

Holick has been busy making a name for himself for years and presents himself as the respected vitamin D scientist but further investigation on my part, as well as others, tells me he is being paid thousands of dollars by the tanning bed industry, among other things.

I’ve been investigating this issue for many years. I’ve read countless scientific studies on both sides of the topic and also many different kinds of studies. I was hoping that a small amount of sun was a good thing but the credible evidence is clear. UVR “does” cause cancer. No ifs, ands or buts.

Also, I’ve been taking about 1000 IU’s of vitamin D for 37 years because I think vitamin D is very important and it was “easy” to get enough, even when I was very poor. You can also irridate vedgetables, like mushrooms and get 100% of the daily value.

Most people now days don’t drink milk; they drink soda-pop. I think it is a likely cause of the epidemic of vitamin D deficiency.

I used to believe that a little sun was good until I came down with an auto-immune disease, Ankylosing Spondylitis and a skin disease, Melasma. I had to stay out of the sun and wear a hat and I was not happy about it.

I have stayed out of the sun with sunscreen and a hat for 26 years. I had a complete bone composition test that proved my bones are in excellent condition. That alone tells a story. And before, when I was getting a little sun, my auto-immune disease would flare up and I would get sick.

If Dr. Holick was correct in any of his UVR theories, I wouldn’t be so healthy now. And my mother’s family, who still believes a little sun is necessary, have had everything that the UVR theory proclaims to prevent. My very health conscious “thin” mother came down with invasive breast cancer.

At this point, I can’t understand why anyone would risk radiation, that does cause cancer, because they think the only “real” protection against disease is from vitamin D3 through UVB exposure, the burning rays..The average life span was only 49 years at the turn of the 20th century. Skin cancer and other cancers usually don’t show up until after age 50..It’s not smart to risk skin cancer and auto-immune suppression now days when we know how to “safely” get vitamin D.

Dear Narek, the point is that _UVB_ radiation seems to have a protective effect on melanoma and there definitely exists evidence to back this up:

http://www.youtube.com/watch?v=eeXtGHSt-5o

The main points are that melanoma is the most dangerous form of skin cancer and that it’s occurence has risen far too much to be explained by increased sun exposure alone. The main question is that how changed habits aka HOW people get their sun exposure explain this and how sunscreens do seem to associate with an increase on melanoma occurence.

People who get their “sun fix” too fast and are exposured to mostly UVA without enough UVB radiation are in the melanoma risk zone, or so it seems. For example, wind shields of cars let some UVA through but none UVB.

The fact that UVB is very easy to block may be the main problem, because UVA is what causes the most problems _in absence of_ protective vitamin D (and therefore also melanin) on the skin.

Johny Bourduex P.H.D. is presenting the same arguement that has nothing to back it up. This information is backwards. For starters the vitamindcouncil.org is not a reputable web-site claiming, among others nonsence, that UVR actually prevents Melanoma.

It’s too bad that seemingly smart people steer others in dangerous directions. My hope is to save someone from the agony of cancer caused by UV Radiation and to take the time to find reputable information. It is not an easy task to find it on the internet.

There are many more skin cancers than any other type of cancer. The evidence is mounting against all radiation, especially the sun. UVR hurts immunity and damages the DNA of the skin. These two factors contribute to cancer. I’ve read that most cancers and STDs start in, or right after the summer because of lowered immunity.

These crusaders promoting sun exposure to be healthy are fighting against the very people who have been saving lives because of their personal dedication to finding the truth with the ongoing science that follows the “logical sequence of facts”.

Bottom line: All radiation is cumulative and most of us have already had way too much..

Nakek said:

“The American Cancer Society says over and over that the number one risk factor for cancer is obesity. Other factors at the top of the list are cigarette smoke and radiation.”

Obesity also seems to count for whopping 90% of variance regarding to Vitamin D dosing. So obese people may need even 10 times more vitamin D than thin people. Their bodies may use it more, but the real problem is that vitamin D binding protein “devours” cholecalsiferol to adipose tissue, where it remains fairly inactive. So real storage for vitamin d seems to be blood serum, in my eyes, for most people. And you MUST get the raw material, Vitamin D, pretty much all the time, probably preferably to the levels that nature uses. I have my take on that “nature” later in this post.

Regarding obesity, vitamin D has been linked to secretion and sensitivity of adinopectin ja leptin – two hormones that seem to affect fat metabolism ja hunger sensations greatly. People tend to be thinner during summer and fatter during winter. This has been observed in cultures that do not “take sun” compared to outdoor cultures. The Arabi women with their burkhas are often obese, believe me.

People who get cancer diagnosis during summer seem to have several times better prognosis than those who are diagnozed during winter. This has been shown over and over and realistically, the ONLY reasonable theory for this phenomenon revolves over Vitamin D.

“It’s easy to get your Vitamin D from food and or supplements!”

If and when we actually open our eyes for a second, what dose do you think that is relevant to human physiology – the “healthy level”? Do you realy think “we” are getting enough D3 from fish, milk and such? The dose we get from food is around 400-600 IU per day, which in my book is a dangerous joke. So supplements are a must and those supplements must be high-dose ones.

Heaney et al. did a landmark study in 2003, when they discovered that healthy humans use between 3000–5000 IU of vitamin D a day (if they can get it). This is approximately 10 times more than what the Food and Nutrition Board says is adequate intake. What’s even more interesting, Heaney himself commented that 3000-5000 IU still counts for only about 80% of vitamin D what we actually physiologically need.

I must assert that any talk about Vitamin D should maintain a context that takes it’s unique pharmacological profile into conversation.

Intentional, full-body sun exposure generates 10 000 – 50 000 IU vitamin D via minimal erythmeral dose towards maximum of several doses, ie the level that makes skin pink before burning.

Creighton trial was impressive, yet I think that unusually high rates of cancer in plasebo group could also be interpreted that vitamin D may have properties that make it even more versatile in cancer prevention. That is, if we believe that calcium alone ja vitamin D:s ability to help calcium bioavailability and absorption wasn’t the reason for diminished cancer count, why anyone wasn’t critisizing the STILL minuscule dose of 2000+ IU? Human body USES and very probably NEEDS at least 3 three to six times that amount, daily.

Where does the “excess” go to? Any ideas? It kills cancer cells! And we know several mechanisms as well. This isn’t rocket science.

I happen to have Crohn’s disease and as Ollie revealed, there are several clinical trials going on vitamin D as a possibel denominator in Crohn’s. Nice to know!

My Crohn’s went to 95% remission when I started to take vitamin D 100-200 µg per day and the change was fast – far faster (8-10 times) than on immunosuppressants. I even had brakes for several weeks 5-6 times and the effect was obvious, every time! More symptoms (even to the stage of going to hospital) when I was off, much less when start taking D3. Of course, no doctor here in my country wants I use or recommend vitamin D physiological doses, because vast majority of doctors still DO NOT read nothing about vitamin D, because it’s not a drug, it’s a vitamin. And vitamins overall are not hot topic these days.

Crohn’s disease is associated with the rise of TNF-alfa activity. Vitamin D affects (dangerously high) pro-inflammatory cytokine TNF-alfa levels in vitro and in vivo, even in humans. Actually, some of the most expensive medications on market for Crohn’s, the biological antibodies like infliximabi and adalimumabi, do the same thing and nothing else. Vitamin D on the other hand, IS a hormone after metabolizing process in the liver and has as many mechanisms of action as over 2000 genes it regulates.

Another epidemiological study came out just 3 months ago which positively linked Crohn’s with lack of sunlight (read: latitude). Somehow I’m not surprised.

Speaking from the topic again, vitamin D may lessen the risk of colon cancer far more than 5-ASA medications, which doctors recommended for years JUST FOR THAT effect on Crohn’s.

I could go on and on. Oliver’s great former text compared adequate sunlight exposure in Scotland and it’s calculated melanoma risk to vitamin D:s positive effect on falls and fractures. The comparison effect was 2000:1 in favor of sunlight/vitamin D. In EU, the same rate could be counted to be 160 billion euros per year. In Canada alone, providing people enough vitamin D would be about 8 billion dollars. Take your pick.

Now that vitamin D deficiency has been established (Mofazzarian et al.) as an INDEPENDENT and strong risk factor coronary heart disease, what are we waiting for here?

I could waste my time ranting about single effects of D3 but instead I pledge you to read just HOW far the vitamin D science has gone – mostly in the last 15 years. The results are nothing short of staggering:

http://www.vitamindcouncil.org/research.shtml

One last point on Vitamin D i want to make is it’s cutaneous production rate from sun. Prepare to be surprised:

“Studies show that if you go out in the summer sun in your bathing suit until your skin just begins to turn pink, you make between 10,000 and 50,000 units (250-1000 µg/d) of cholecalciferol in your skin. Professor Michael Holick of Boston University School of Medicine has studied this extensively and believes a reasonable average of all the studies is 20,000 units. (500 µg) That means a few minutes in the summer sun produces 100 times more vitamin D than the government says you need!”

Talking about any studies done on 10 µg (or 400 IU) doses, I would say just one thing:

“HOAX”

Oliver Gillie PHD is basing his Vitamin D evidence from the type of scientific evidence used by Dr. Linus Pauling, who advocated for years that Vitamin C prevented cancer. The big difference this time is sun exposure is radiation. Radiation “does” cause cancer. If this actually makes sense to any doctor, they are in the wrong profession.

Science can’t afford another scientist like Pauling. This type of evidence is dangerous. If what Dr. Gillie proclaims is true, for example, why are many of the new cases of Melanoma coming from young people who were regularly using tanning booths?

If you want the real scientific facts, go to skincancer.org or The American Cancer Society, cancer.org. Dr. Pauling died of cancer. And The American Cancer Society wrote that other vitamins, like beta carotene and folate, that were promoted in the past, actually caused more cancers!

Dr. Len Lichtenfeld from ACS wrote: “If we hadn’t done the research, we would all be taking large doses of vitamin C to prevent cancer (it doesn’t). We would never have found out that beta carotene leads to an increased risk of lung cancer in heavy smokers. We wouldn’t know that vitamin E and selenium–alone or in combination–did nothing to reduce prostate cancer in men. First folate was reported to reduce the risk of colorectal cancer. More recently, some research suggests that folate may promote polyp growth for people who already have colon polyps possibly resulting in an increased risk of colon cancer. Next on my list is vitamin D. Maybe we are looking for cancer prevention in all the wrong places.”

I am not only motivated by personal cases of Melanoma, which did not follow the protocol that Dr. Gillie presents. I am baffled by the collection of so-called wisdom of junk science and the countless people hurt by it in my 56 years of life.

And it wasn’t that long ago that cigarette companies had a host of doctors telling the public that cigarettes do not cause cancer.

The average person does not have time to do all of the research to make logical decisions about their health. And the vitamin D hype is a sea of madness when you try and find reputable information from the internet. This is truely scary!

Dr. Mercola, internet, modern day, snake oil salesman is selling sun lamps so people can get the natural vitamin D that you need to protect against cancer? Bullcrap…Junk science.

Thanks for your comments on logic PL Hayes, but this is not a philosophical competition. I am confident that readers interested in the facts and in scientific interpretation will understand me correctly. Why dont you say more and explain where you are coming from on this and why you are quibbling about linguistic usage.

Narek seems to be concerned about friends or family who have suffered from melanoma, which is very understandable. It is a tragic disease can be merciless once established.

However an understanding of how best to prevent melanoma has been hampered by dermatologists committed to one hypothesis and one way of trying to prevent it – by avoidance of exposure to the sun. This approach has overlooked crucial facts about the disease. It is has been known for a long time that outdoor workers get less melanoma than others and there is also evidence suggesting that those who have longer sun exposure without burning get less melanoma. These facts can only be understood by taking into account the role of vitamin D.

In short the explanation most consistent with all the facts we have is that melanoma is caused by burning of the skin by sun in people with low vitamin D levels. It seems that vitamin D, obtained mostly from sun exposure, prevents melanoma in the same way that the vitamin prevents a number of other cancers. People such as outdoor workers who are replete with vitamin D because they are regularly exposed to the sun seem to have least risk of melanoma. People who avoid the sun have very low vitamin D levels and so are likely to be greater risk of melanoma if they do by chance get burnt.

Advice from dermatologists promoted by cancer charities here and in Australia has created sun phobia and lowered vitamin D levels. This has put people at greater risk of cancers of all kinds and several other chronic diseases including heart disease, diabetes, raised blood pressure, stroke, arthritis, multiple sclerosis and much more. That is the compelling conclusion from much observational data, but it is also supported by a number randomised controlled trials.

Many more randomised controlled trials of vitamin D for prevention of chronic disease are now being undertaken or planned. Some 25 trials of vitamin D for prevention of cancer have been registered, 9 trials for prevention of heart disease, 13 for diabetes, 4 for arthritis, 5 for Crohn’s disease, 9 for other immune system disease, 4 for cystic fibrosis, 4 for muscular weakness, 7 for infection. We don’t know the results of these trials yet. But we do know that it is the opinion of the scientists planning these trials that vitamin D is likely to do something to prevent these diseases or they would not be undertaking the trials. Trials are expensive, laborious and difficult. Nobody undertakes a trial unless they believe there is a very good chance of a positive outcome.

You can be sure that most of these scientists and their families will be taking a vitamin D supplement and revising their view of risks and benefits of sun exposure.

Despite their sunny climate many Australians have a very low blood level of vitamin D. This is a result of the sun phobia induced by the slip, slap, slop campaigns. Scientists and health experts in Australia now realise that these campaigns have gone too far. To take just one telling observation: multiple sclerosis is five times more common in temperate Tasmania than in sub-Tropical Queensland. They all eat the same food and have the same Irish/English genetic background – the only difference between Australians living in the south and north of the country is the amount of sun they get.

So now Australians are being told to get at least some sun every day. In the past schoolchildren in Australia were not allowed out to play without a hat: no hat, no play. Now Tasmanian schoolchildren are being told to take their hats off in winter so they can benefit from the thin winter sun.

It is now widely accepted that insufficient vitamin D in pregnancy and/or early life is a cause of MS. In Scotland one in 500 people suffer from the disease compared with one in about 750 in England. This is almost certainly a result of Scotland’s cloudy, rainy climate. The prevailing westerly wind comes straight from the Atlantic into the lowland corridor linking Glasgow and Edinburgh where most Scots live. White skin makes vitamin D five to ten times faster than dark skin. The palest skin type of all, pink with freckles, has evolved on the Celtic fringe where the UVB is as low as it is within the Arctic Circle. Eskimos may get as much vitamin D from the sun as Glaswegians but they also benefit from all the oily fish they eat.

It is impossible for us to get more than about five percent of the vitamin D we need from our diet – unless, like Eskimos, we eat oily fish three times a day.

England gets more sun than Scotland, not only because it is further south but because much of the country obtains some protection from the Irish landmass to the west and the mountains of Cumbria and Wales which draw down precipitation. Even so the English climate is generally very cloudy and we need to take every opportunity to sunbathe without burning and obtain vitamin D.

Cancer Research UK has changed its advice in the last couple of years. It is less extreme than it was. Previous advice, if followed to the letter, would have made people seriously deficient in vitamin D with adverse health consequences for many. People really need to be told to go out in the sun and remove as much clothing as possible and expose their skin for at least a few minutes. Gradually the time of exposure may be built up safely so burning is avoided.

Those who don’t like the sun or remain worried about melanoma would be well advised to take a supplement of vitamin D – at least 1000 IUs per day are considered a safe dose by EU authorities and 2000 IUs is considered a safe daily dose by US authorities. The Canadian Cancer Society advises Canadians to take vitamin D in winter and all year round if they don’t get much sun – and most Canadians have the opportunity to get a lot more sun than most of us do in the US because of their continental climate and because many live at a latitude equivalent to the Mediterranean.

The information and ideas outlined here are explained in much more detail in two publications which are available as a free download from http://www.healthresearchforum.org.uk:

Sunlight Robbery – Health benefits of sunlight are denied by current public health policy in the UK. Sir Richard Doll, doyenne of health research commented on this book: “I am most impressed with the way Gillie has collected and presented the evidence”.

Scotland’s Health Deficit: an explanation and a plan. Sir Muir Gray, eminent health advisor, commented: “I was very impressed by the strength of evidence and by the conclusion…The work is of importance and a great achievement.”

Finally I think we should thank Bill Grant who has filed his research findings and thoughts with Cancer Research UK. It should provide the distinguished charity with an opportunity to think again about its policy in this area and help with the public debate.

With all do respect to Dr. Grant, I think your logistics are ridiculous. First of all, to get any information from landesbioscience, you have to subscribe to the magazine; second, pubmed.gov doesn’t proclaim that people “need” to get in the sun for Vitamin D requirements. Also, some of these scientists are writing books and literature and appearing in the media to promote themselves like, Dr. Michael F. Holick and the Garland Brothers, Cedric and Frank.

Dr. Holick posed in a tanning bed for USA Today Magazine. On pubmed.gov I noticed their report on the dangers of tanning salons. Drs. Holick and the Garland Brothers are using scientific evidence that the American Cancer Society reports has no credibility. People in Australia, for example, have very high levels of cancers and they are abundant with sunshine.

Personally, I would consider sueing Dr. Holick, the Reader’s Digest expert and Dr. Mercola, the modern day, snake oil, cyberspace salesman, because people I care about, who have followed their advice for years, are getting one thing after the other as time goes on. People who take very good care of themselves in every way are coming up with cancer, heart attack, atrial fibrillation, kidney infections, diabetes, leukemia, dimentia, arthritis, alcholism, depression and on and on.

The American Cancer Society says over and over that the number one risk factor for cancer is obesity. Other factors at the top of the list are cigarette smoke and radiation.

It’s easy to get your Vitamin D from food and or supplements!

Since we UVB/vitamin D/cancer scientists are still upset with the IARC Working Group 5 Report, Vitamin D and Cancer, fourteen of us wrote an open letter to the new IARC Director, Christopher P. Wild, Ph.D., which has just been published in Dermato-Endocrinology:
Cedric F. Garland, William B. Grant, Barbara J. Boucher, Heide S. Cross, Frank C. Garland, Oliver Gillie, Edward D. Gorham, Robert P. Heaney, Michael F. Holick, Bruce W. Hollis, Johan E. Moan, Meinrad Peterlik, Jörg Reichrath and Armin Zittermann. Open Letter to IARC Director Christopher P. Wild: Re IARC Working Group Report 5—Vitamin D and Cancer. Dermato-Endocrinology 2009 March/April;1(2):119-120.
http://www.landesbioscience.com/journals/dermatoendocrinology/article/8512/

Access to this open letter is free, but one must register to download the letter.

In Director Wild’s response, he defended the IARC Report, condidering it a balanced presentation of the current state of hte evidence. While he declined an offer to have his letter published alongside ours, why not read our letter and see whether you think his response was appropriate. You might also go to http://www.pubmed.gov and search using “vitamin D cancer” to find papers that have appeared since a few months before the end of 2008 and, therefore, were not included in the IARC Report preparation.

Why are doctors more worried about Rickets making a comeback than the very real epidemic of Skin Cancer, especially Melanoma? Most of the Rickets cases are among the black race, in the USA. In my life, I don’t know one child with rickets or one adult with Osteomalcia and I am 55 years old. I know lots of people who developed skin cancer and 4 with Melanoma, 2 died from it. Rickets are easily prevented and Osteomalicia, easily prevented and treated!

Doctors have responded to the Vitamin D hype that was originally sensationalized by Vitamin D experts, like Dr. Holick. Investigating his research, reveals how irresponsible and contradicting his advice is, which he has been promoting, actively, for years.

I believe Vitamin D (it’s really a hormone) to be essential to good health but doctors should get off the band wagon of promoting a “little” sun. Isn’t that the same as advising one cigarette a day to prevent weight gain? Are doctors just assuming people won’t stop drinking soda pop, instead of milk, so the sun is the lesser of two evils?

A little sun is all it takes to trigger Melanoma. Whether or not the perfect study with the high dose of Vitamin D proves Vitamin D prevents cancer, it’s irresponsible to promote “any” sun exposure. It does hurt immunity. That was proven many years ago. And it is cumulative, like all radiation. And what else don’t we know about the dangers of radiation? And why, in all these studies and treatments for low Vitamin D levels, do doctors and scientists always instruct to take the supplements and not UVR exposure?

I much appreciate the effort and concern that has gone into the posting of all these comments. However, at the end of the day, the question as to whether adeqaute vitamin D status should be ensured in order to provide measurable protection against various cancers and against the many other disorders with which poor vitamin D status is associated cannot be resolved satisfactorily without adequately powered RCTs using adeqaute doses of vitamin D being carried out across various communities and ethnic groups. The sooner everyone involved in these circular arguments uses all thier energy and drive to ensure that such RCTs get done the sooner we will have the facts necessary to provide valid answers on these issues. This said, one major reason for being concerned about this particular IARC report is that funding bodies could find it difficult to support such trials, which many commentators on this site clearly want, whilst this report stands as it is. Hence the push to ensure that this issue is examined from every point of view. If such an examination fails to provide definitive answers, then RCTs of vitamin D supplementation must go forward.
Rickets was wiped out world-wide within a generation by cod liver oil and ‘fresh air’ but rickets is now increasingly common due to lack of supplementationn and our retreat from the sun and inadeqaute vitanin D status is common at all ages across the globe, almost 100 years after vitamin D was discovereed. Let us make sure that it isn’t another 100 years before we have the answers we need as to whether non-bony disorders can be reduced as dramatically as rickets and osteomalacia, by supplementation, even if we have to continue to avoid getting sunburnt by limiting our exposure to ultraviolet light.

Barbara J Boucher

I think Ed Yong does an exellent job of making sence out of a confusing, contradicting issue about Vitamin D preventing cancer. If you analyze what these studies have and haven’t proven, the obvious conclusion is, there really isn’t any real evidence that Vitamin D prevents any cancers. And if people go ahead and expose their skin to UVR, in order to prevent cancer, the prevention might be worse than the disease.

Then William Grant presents that the scientists were obviously biased. But it’s obvious to me that he is the one that is biased with claims that haven’t been proven. Then “his” credible scientist happens to be DR. Michael F. Holick. Dr. Holick has been paid a huge amount of money by the Tanning Industry and his book, The UV Advantage, is riddled with flaws. He recommends using a lot of exposure to UVR from tanning beds in order to get the best kind of Vitamin D, from UVR instead of suplements. In “USA Today”, he posed in a tanning bed. How stupid is that?

The bottom line to all of this is, UVR is cumulative like all radiation. Your skin never forgets. Most of us have already had way too much. I think a great deal of the bias comes from people worshipping the sun like a religion. People want to believe it and it’s a quick fix. If Vitamin D is proven to be a cancer prevention, great! But why in the world expose our skin to the sun to get it?

At the beginning of the 20th century, the average life span was 49. Skin cancer doesn’t usual show up until after age 50. Every hour in this country, someone dies of Melanoma! It’s happened to people in my life. It is a truly horrible affliction!

I agree with Dr Grant-in addition, the pharma industry knew about the anti cancer effects of vitamin D in the lab many years ago and spent billions trying to produce analogues of vitamin D that could be patented, but the biochemistry of the body out smarted the chemists and they failed. At the very least all the epidemiolgy data on vitamin D provides a strong signal that it has anticancer effects. So do the controlled studies that are needed. The signals have been there for years and yet still the needed studies have not been conducted. And Dr Yong when you do the studies dont use 400IU. Use a dose that has a chance to show an effect!!!!

My detailed critique of the IARC report has been published with open access at
http://www.landesbioscience.com/journals/dermatoendocrinology/toc/1/1

Grant WB. A critical review of Vitamin D and cancer: A report of the IARC Working Group on vitamin D. Dermato-Endocrinology. 2009;1(1):25-33.

Along with an accompanying editorial:
Holick MF. Shining Light on the Vitamin D-Cancer Connection IARC Report
Dermato-Endocrinology. 2009;1(1):4-6.

And a previous paper:
Grant WB. How strong is the evidence that solar ultraviolet B and vitamin D reduce the risk of cancer? An examination using Hill’s criteria for causality. Dermato-Endocrinology. 2009;1(1):17-24.

“All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.”
~ Arthur Schopenhauer Quotes

It appears that the UVB/vitamin D/cancer theory is in Stage Two.

To answer your points:

Reason #1. The expert scientists were well-versed in the adverse effects of UV irradiance but not well-versed in the beneficial effects. Thus, they brought a bias to the review that was clearly evident in how they readily accepted observational evidence that UV increases the risk of melanoma and skin cancer but dismissed over 95% of the evidence that UVB reduces the risk of internal cancers. It seems apparent that they were trying to protect their message that UV irradiance should be avoided in order to reduce the risk of skin cancer and melanoma, even though vitamin D could be obtained from supplements rather than UVB irradiance.

The working group responsible for the report include over 20 experts in the field of vitamin D and many of them have been looking at the links between vitamin D and cancer with great interest. Your accusation of bias among the group’s members is not based on the evidence. In particular, the report states that some of the members were invited “because of their expertise in methodological issues”, which lends greater strength to the report’s analysis of the strengths and weaknesses of various studies.

Reason #2. The report did not fairly review the ecological studies. It is correct that latitude is not a good index of vitamin D production in Europe north of about 40˚, and that other factors such as diet, alcohol consumption, and smoking have more important impacts on cancer risk than does UVB (2). However, the Report did not reference or discuss an ecological study for the United States that used summertime UVB doses as well as indices for alcohol consumption, ethnic background, smoking, socioeconomic status, and urban/rural residence (3). This study, which used mortality rate data for two periods, 1950-69 and 1970-94, found inverse correlations with summertime UVB for 14 types of cancer, gastrointestinal tract, female other than cervical, urogenital cancers and lymphomas. In the United States, there is an asymmetry for summertime UVB doses with doses in the states east of the Rocky Mountains much lower than doses to the west due to higher surface elevation and thinner stratospheric ozone layer in the west. This pattern is readily apparent for most of the 14 types of cancer.

The report is not alone in criticising ecological studies in this area – several other reviews have pointed out the flaws in making causal conclusions based on such methods and we have nothing further to add regarding the weaknesses of these studies that we have not written about in the post. The future of research into vitamin D and cancer lies in clinical trials and large-scale observational studies that directly measure how much vitamin D people have in their blood (specifically, its metabolite, 25-hydroxyvitamin D).

Reason #3. Perhaps the most egregious error of the report was its summary dismissal of the only randomized controlled trial of vitamin D and cancer incidence in which sufficient vitamin D was used. This study involved over 1000 post-menopausal women in Nebraska who were divided into three groups and followed for four years. Those taking 1100 IU/day of vitamin D and 1500 mg/day of calcium had a 77% reduction in all-cancer risk between the ends of the first and fourth years (4). In comparison with those taking 1500 mg/day of calcium and those taking a placebo, a 35% reduction in all-cancer risk was attributed to the vitamin D dose.

The report’s analysis of the Nebraska trial was carefully considered and not, as you say, a “summary dismissal”. The trial’s weaknesses have been criticised elsewhere (see page 238 of the report for references) and the IARC report concludes that “the statistical analysis of the trial was not correct” and the “design of the trial was biased”. The group who received a placebo had unusually high rates of cancer, which would have increased the chances of finding that vitamin D supplements have a protective effect. The trial also found that calcium supplements alone reduce the risk of cancer to a similar extent as vitamin D and calcium supplements combined. The trial’s results were actually “negative for vitamin D”. We stress again that many of the scientists who contributed to the new report were chosen for their expertise in the methods used in scientific studies.

Reason #4. The Report considers the finding regarding vitamin D and bowel cancer to be a mere “association.” However, my review of the literature on vitamin D and cancer risk finds that UVB and vitamin D can be considered causal risk-reduction factors for cancer (5) when evaluated according to Koch’s postulates as enunciated by A. Bradford Hill (6). For example, the mechanisms whereby vitamin D reduces the risk of cancer are well known (7).

The report is very clear that the evidence for a causal link between vitamin D and bowel cancer is not strong enough at this stage. This is why they have called for clinical trials to demonstrate that restoring adequate vitamin D levels can lead to a lower risk of bowel cancer, or of dying from it. Note that we are not dismissing links between vitamin D and cancer. Elsewhere on our website, we say that there is growing evidence that vitamin D protects against bowel cancer. But we agree with the conclusions of the IARC report that the evidence regarding other cancers is weak and inconsistent. In contrast, the link between UV radiation and melanoma is readily accepted because it is supported by a large body of evidence from multiple types of research.

Reason #5. Finally, the Report was, in my opinion, disingenuous in pointing to vitamins that did not live up to their promise in reducing the risk of cancer as a reason to reject the UVB/vitamin D/cancer theory. After all, vitamin D supplementation did practically eliminate rickets.

The report did not, as you say, use the failed promise of other vitamins to “reject the UVB/vitamin D/cancer theory”. It did, however, suggest the unexpected results from these trials should give us reason to be cautious so as not to inadvertently cause public harm through unsubstantiated recommendations. The benefits of vitamin D in eliminating rickets was noted by the report but is irrelevant for discussions regarding cancer.

Vitamin D does protect against cancer

The IARC Report 5: Vitamin D and Cancer (1) should not be considered a definitive review of the evidence that solar ultraviolet-B (UVB) irradiance and vitamin D reduce the risk of cancer for the following reasons:

Reason #1. The expert scientists were well-versed in the adverse effects of UV irradiance but not well-versed in the beneficial effects. Thus, they brought a bias to the review that was clearly evident in how they readily accepted observational evidence that UV increases the risk of melanoma and skin cancer but dismissed over 95% of the evidence that UVB reduces the risk of internal cancers. It seems apparent that they were trying to protect their message that UV irradiance should be avoided in order to reduce the risk of skin cancer and melanoma, even though vitamin D could be obtained from supplements rather than UVB irradiance.

Reason #2. The report did not fairly review the ecological studies. It is correct that latitude is not a good index of vitamin D production in Europe north of about 40˚, and that other factors such as diet, alcohol consumption, and smoking have more important impacts on cancer risk than does UVB (2). However, the Report did not reference or discuss an ecological study for the United States that used summertime UVB doses as well as indices for alcohol consumption, ethnic background, smoking, socioeconomic status, and urban/rural residence (3). This study, which used mortality rate data for two periods, 1950-69 and 1970-94, found inverse correlations with summertime UVB for 14 types of cancer, gastrointestinal tract, female other than cervical, urogenital cancers and lymphomas. In the United States, there is an asymmetry for summertime UVB doses with doses in the states east of the Rocky Mountains much lower than doses to the west due to higher surface elevation and thinner stratospheric ozone layer in the west. This pattern is readily apparent for most of the 14 types of cancer.

Reason #3. Perhaps the most egregious error of the report was its summary dismissal of the only randomized controlled trial of vitamin D and cancer incidence in which sufficient vitamin D was used. This study involved over 1000 post-menopausal women in Nebraska who were divided into three groups and followed for four years. Those taking 1100 IU/day of vitamin D and 1500 mg/day of calcium had a 77% reduction in all-cancer risk between the ends of the first and fourth years (4). In comparison with those taking 1500 mg/day of calcium and those taking a placebo, a 35% reduction in all-cancer risk was attributed to the vitamin D dose.

Reason #4. The Report considers the finding regarding vitamin D and bowel cancer to be a mere “association.” However, my review of the literature on vitamin D and cancer risk finds that UVB and vitamin D can be considered causal risk-reduction factors for cancer (5) when evaluated according to Koch’s postulates as enunciated by A. Bradford Hill (6). For example, the mechanisms whereby vitamin D reduces the risk of cancer are well known (7).

Reason #5. Finally, the Report was, in my opinion, disingenuous in pointing to vitamins that did not live up to their promise in reducing the risk of cancer as a reason to reject the UVB/vitamin D/cancer theory. After all, vitamin D supplementation did practically eliminate rickets.

Thus, the IARC Report should not be used as the basis for health policies with respect to vitamin D and cancer.

Disclosure
I receive funding from the UV Foundation (McLean, VA), the Vitamin D Society (Canada), and the European Sunlight Association (Brussels). However, none of these organizations has reviewed this response.

References
1. IARC report: Vitamin D and Cancer (Nov. 25, 2008)
http://www.iarc.fr/en/Media-Centre/IARC-News/Vitamin-D-and-Cancer

2. Grant WB. An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates. Cancer. 2002;94:272-81.

3. Grant WB, Garland CF. The association of solar ultraviolet B (UVB) with reducing risk of cancer: multifactorial ecologic analysis of geographic variation in age-adjusted cancer mortality rates. Anticancer Res. 2006;26:2687-99.

4. Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr. 2007;85:1586-91.

5. Grant WB. How strong is the evidence that solar ultraviolet B and vitamin D reduce the risk of cancer? An examination using Hill’s criteria for causality. Dermato-Endocrinology, 2008 epub.
http://www.landesbioscience.com/journals/dermatoendocrinology/article/Grant2DE1-1.pdf

6. Hill AB. The Environment and Disease: Association or Causation? Proc R Soc Med 1965; 58:295-300.

7. Ingraham BA, Bragdon B, Nohe A. Molecular basis of the potential of vitamin D to prevent cancer. Curr Med Res Opin. 2008;24:139-49.