Springtime is here, and so once again is Vitamin D.
You may remember it was about a year ago when a lecture given at the American Association of Cancer Research annual meeting stirred considerable interest when the story was picked up by an astute Associated Press reporter.
By May, the newswires, television, and other media were awash with stories that we needed to get more sun to increase our stores of Vitamin D, and reduce our risk of cancer among many other maladies.
The fear among many of us was that the story would get muddled, and that a considerable amount of effort that has gone into cancer prevention relative to excess sun exposure would go by the wayside as everyone headed to the beach to increase their vitamin D, their tans, and their sunburns.
The main problem was that aside from a handful of advocates, there weren’t many in the scientific and medical community who were prepared to respond to these proclamations, some of which came from recognized and highly regarded researchers.
In short, we didn’t have a very clear and cohesive message to tell you what to do, how to do it safely, and what general agreements had been reached on the benefits of vitamin D.
It is now another year and we are once again “in season” for vitamin D. So, buckle up for this lengthy blog of current events on the vitamin D “scene.”
A couple of weeks ago I had the honor of participating in a conference in Toronto, Canada which brought together a number of experts in the field of vitamin D, sun exposure, and health.
(We have begun a process to identify consensus statements on what we learned from that conference. Unfortunately, it is premature to discuss our conclusions, since those discussions are still in progress. I am comfortable discussing my sense of the public presentations at the Canadian conference, since these were public and do not represent the opinions of those currently involved in the consensus discussions.)
What did I learn from this conference?
First, there is general acceptance that our current levels of vitamin D, as measured in the blood, are too low for general good health. We are not just talking about cancer here, but we are also concerned about bone health, cardiovascular disease, possibly multiple sclerosis and other illnesses.
My sense is that over time government agencies and others will strive to increase the amount of vitamin D we either “create” from sun exposure or take in vitamin supplements or in fortified foods such as milk and other dairy products. (I was surprised to learn that the amount of vitamin D we get from milk is minimal, and there is no vitamin D added or present in many other dairy products. Bottom line: if it isn’t labeled as containing vitamin D, it isn’t there.)
Second, there are three basic ways for us to get vitamin D: increased sun exposure, dietary fortification, or vitamin pills. (Look for vitamin D3 in this latter category, since this is the active form. It is also labeled as cholecalciferol on some bottles.)
There are no known adverse effects from fortification or supplements. However, my dermatology colleagues are caught in the conundrum that increased sun exposure leads to increased risk of skin cancers, both of the fatal type (melanoma) and the usually non-fatal (but potentially disfiguring) basal and squamous cell types.
In response to a specific question, some of the experts I rely on indicated that the risk of increased cancer is directly related to the total amount of sun exposure over time, implying that there is no definitely safe daily dose of sun exposure. Bottom line here is that damage accumulates over time.
The conundrum part is that people should be spending time out of doors. Exercise is good for us, and a “no sun” policy is simply not realistic.
All of this sunshine vs. vitamin pills debate is further complicated by the fact that there is not now (and I predict never will be) a one-size-fits-all recommendation for sunshine exposure that will answer everyone’s needs. (I am having difficulty with those who say a 15 minute walk down the street during the day is adequate to replenish your vitamin D.)
Science tells us there are many variables that influence how much vitamin D our bodies will make after being exposed to the sun. Where you live (think Canada, Maine and Florida), the type of skin you have (burn easily vs. tan without a problem), the amount of skin pigment (fair skinned vs. dark) all influence the amount of vitamin D you will make.
Fifteen minutes of sun can be one person’s dream dose and another’s skin cancer dose.
It is simply too complicated to provide a simple recommendation and the risks of long term damage remain.
So, for my money, it is going to be supplements and sunscreen. The risks of the alternatives are too great, and frankly I don’t have the time during the day to go walking around our neighborhood at the opportune times of the day.
As to the effect of vitamin D on reducing cancer risks, my sense from listening to the experts is that there really is something there. There are too many studies with too much data to ignore the suggestion that vitamin D may reduce the risk of developing some cancers. There is also intriguing evidence that increased levels of vitamin D may improve survival of people who are diagnosed with cancer.
Finally, based on what I heard at the conference, we are going to be hearing not only about how much we should increase our intake of vitamin D. There is going to be serious discussion about whether there is a real risk of danger in doing so. Some experts do not believe that would be a problem. The current “safe level” of vitamin D intake may well be revised upward in the not too distant future.
And that increasing understanding of what a safe level is, and what levels we should have in our blood, may then lead to making a measurement of vitamin D in your blood as much a part of your annual physical as measuring your blood pressure and your cholesterol.
The problem with all of this, if there is a problem, is that this is all based on inferential data.
In the past there have been reports about the benefits of various vitamins such as vitamin C, vitamin E, and beta carotene. When more detailed scientifically controlled studies were done no benefit was found. In fact, in the beta carotene study which was supposed to reduce the risk of lung cancer in heavy smokers, the exact opposite effect was found, namely MORE smokers who took the vitamin died.
The conclusion here is that what seems so obvious is sometimes not so obvious, and requires additional studies to demonstrate whether or not the effects are real.
Then this past week, a group of highly regarded epidemiologists from Harvard published a study in the Journal of the National Cancer Institute (JNCI) which was accompanied by an editorial, discussing a research study which tried to look at predictors of vitamin D exposure over many years and correlate that assumption with the risk of developing and dying from a number of cancers. (A technical malfunction on the JNCI website has prevented me from establishing a link at this time.)
Today, at the 2006 annual meeting of the AACR there were two more presentations that discussed the relationship of vitamin D to breast cancer risk, and what we need to do to get our vitamin D levels within range of what the scientists claim is necessary to achieve that risk reduction.
The article in the JNCI looked at an implied measure of vitamin D based on factors that would probably reflect levels of vitamin D in the blood.
Here, the authors followed almost 48,000 thousand men over many years and asked them questions regarding their diets and activities, among other indicators. For the vitamin D research, they determined that dietary and supplementary vitamin D intake, skin pigmentation, adiposity (fat), geographic location, and leisure time physical activity would reflect higher vitamin D levels in the blood.
Those who had higher levels of vitamin D had a 17% decreased risk of developing cancer and a 29% decrease in their risk of dying from cancer. In particular, for digestive system cancers, there was a 43% decrease in the risk of developing one of these cancers and a 45% decreased risk of death. Among the cancers with the most significant decreases was pancreatic, esophageal and colorectal cancer.
Oral cancers also were fewer in those with predicted higher vitamin D levels.
Some other cancers, including leukemia, lung cancer, advanced prostate cancer, renal cancer and non-Hodgkin’s lymphoma were also decreased, but the data were suggestive rather than “significant.”
The authors also noted the information reported in the recent WHI study, where blood levels of vitamin D at the time of entry into the study were associated with a decreased risk of developing colorectal cancer in the women who participated in the study.
How much vitamin D will achieve this benefit? I suspect this may differ from person to person, but 1500 units per day is what these experts recommend.
And I would be remiss if I didn’t emphasize their comments that African Americans in general may need to be especially aware of this recommendation, since darker skin pigmentation interferes with natural vitamin D prediction. The authors comment, as have others, that this vitamin D deficiency may in fact explain some of the higher incidence and worse prognosis for African Americans for several cancers.
The two abstract presentations from the current AACR meeting are more difficult to comment on because they are just what they are: abstracts. There is little information in an abstract, and it really represents an early presentation of data from research that is frequently in progress. (To access these abstracts, go to this link--which is a search engine--and enter 4008 for one abstract, and 4009 for the other where it says "abstract number".)
Based on the information I have been able to obtain, one study (characterized as “preliminary” by the authors) which measured various physical activities and dietary intake of vitamin D could reduce the risk of breast cancer by about 40%. Also, these authors suggested that higher vitamin D levels earlier in life were the key to the beneficial effects they observed.
The other study looked at a “meta-analysis,” which a statistical way of pooling data from a number of previously reported studies, and concluded that at the highest blood levels of vitamin D compared with the lowest levels there was a 50% reduction in the risk of developing breast cancer
The caution here is that the authors state in their abstract that to get to the “good” level of vitamin D you would have to take 2700IU per day which exceeds the current national “safe” intake of 2400IU. (The press release which accompanied the abstract stated that a woman would have to take at least 1000IU every day. I cannot explain this significant discrepancy at this time, but 1000IU is certainly easily achievable through a multivitamin containing 400 IU, calcium supplements that are fortified with 400 IU, and a vitamin supplement containing another 400 IU).
So that’s the latest information on vitamin D.
What should you do?
I have tried to outline my thoughts above, but will repeat them here:
I don’t think there is harm in increasing your vitamin D intake. I would be cautious with regard to excess sun exposure, and I would realize that your personal characteristics make this approach a bit chancy in terms of getting the desired effect without getting the undesired harms.
I wouldn’t take megadoses of vitamin D, unless you are one of those folks with bad osteoporosis under the care of a physician who understands the benefits and risks of high dose vitamin D (I recently answered the question of a lady who heard that she should be taking several thousand units of vitamin D daily when the doctor meant every several weeks).
Whether or not there is real benefit from these recommendations remains uncertain, until more definitive studies are done.
But that doesn’t diminish my enthusiasm to move forward quickly in getting clinical trials started where we can best determine what the right level of vitamin D is, and whether or not it really will have the impact on reducing the risks of cancer, or improving the survival of patients with cancer, as has been strongly suggested by the research noted above.
As a “P.S.”:
I pointed out at the Toronto conference that several years ago the same Harvard researchers published a study in the Annals of Internal Medicine that looked at a large number of nurses and found that the vitamin folate also had a significant impact on the reducing the risk of colorectal cancer, if taken over many years. Despite what appeared to be the same type of evidence we are now seeing for vitamin D, I am not aware that the recommendation to take folate on a daily basis has received much attention. Yet here is a simple, safe and readily available supplement that may also have a significant impact on decreasing your risk of developing colon cancer if you are a woman.
By the way, I did go to a beach during my vacation, and I did use sunscreen, stayed under an umbrella during peak sun hours and wore a hat and a T-shirt. No sunburn, no tan, but a very nice time with my family.