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Vitamin D supplements may slow prostate cancer


3 Star

Vitamin D supplements may slow prostate cancer

Our Review Summary

This story describes a small study designed to see if taking vitamin D pills would slow or reverse low-grade prostate cancers. Since the results from a study like this are likely to generate a lot of interest and could influence patient decision-making, we’d like to see the claims evaluated and explored very thoroughly. The report perhaps too easily accepts the researcher’s conclusion that inflammation “is a driver of cancer,”  fails to adequately quantify the benefits seen in the treatment group, and doesn’t ask tough enough questions about how the study was conducted and its limitations. But although men and women who love their vitamin D may still read this article and run right to the supplementation aisle, the article does make a good faith effort to put the brakes on any runaway optimism over the benefits of the sunshine vitamin.


Why This Matters

As the story points out, men frequently opt for quick (and potentially unnecessary) surgery to remove their prostates even when physicians recommend watchful waiting and careful Gleason Score monitoring of low grade or presumably less aggressive tumors. The reason for the leap onto the operating tables is understandable anxiety over any risk of cancer progression, despite the clear risks of surgery, including infection, incontinence and erectile dysfunction. Preventative steps that might ease anxiety have a long and uncertain history, from soy-based diets to nutrient supplementation, but most of the evidence for their value has been based on problematic observational studies, rather than well controlled clinical trials. This new study, while very small and as yet unpublished in a peer reviewed journal, nonetheless gathers more rigorous information in a randomized study, and establishes some foundation for further and larger studies of vitamin D.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

The story doesn’t address cost. While it can be argued that most patients have a rough idea of the price of vitamin D supplements, a quick word on the monthly cost of supplements, or the potential cost-effectiveness of supplementation as part of a larger watchful waiting approach, would have been useful. The article does point out that vitamin D is available in fortified dairy products and directly from El Sol.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The story says, “many who received vitamin D had improvements in their prostate tumors, while the tumors in the placebo group remained the same or got worse.” It adds some quantification with this quote from a researcher: “In greater than 60 percent of those taking it, vitamin D actually made the cancer better.” But this is not enough information for a satisfactory rating here. How much “better” were the cancers in the vitamin D group? How was this measured? Would the size of the difference be considered meaningful for the patient, or is it merely a “statistically significant” difference? Since findings like this are likely to generate significant interest, the story had an obligation to explore these questions more thoroughly.

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

The potential harms from taking vitamin D supplements were not mentioned (nor were those of surgery).  While toxicity is rare, studies suggest that long-term intakes of high doses are associated with adverse health effects. Perhaps more importantly, what about men possibly taking vitamin D when they really ought to have surgery because they have an aggressive tumor type?

Does the story seem to grasp the quality of the evidence?


The story clears our bar here. It offers a strong rebuttal to the implication that vitamin D is clearly slowing or reversing prostate cancer by quoting a physician not connected to the study. And it does point out this was a small study, not yet published in a journal or subjected to full peer review, that needs to be replicated in a larger sample. Of course, there are many issues that the story could have delved into to increase readers’ understanding of the study. Were the patients and researchers blinded to who got what? How were tumors measured before and after surgery? Was compliance with vitamin D intake monitored? And how can a 60-day study tell us anything meaningful about cancers that may take a decade to impact the health of patients? But for a short piece, we think the story provided the right bottom-line message.

Does the story commit disease-mongering?


No evidence of disease mongering.

Does the story use independent sources and identify conflicts of interest?


The article quotes the chief of radiation oncology at Brigham and Women’s Hospital in Boston in the strongest possible way concluding that the study was too small to establish any value of vitamin D supplements and prostate cancer prevention or therapy. There is no indication that the vitamin supplement industry had any role in the research. However, the article might have pointed out that the researcher, Bruce Hollis, has been conducting studies about the benefits of vitamin D for decades and is a widely quoted expert on the potential benefits of the vitamin in disease prevention. Hollis was quoted elsewhere on this study saying that “doctors should be recommending vitamin D₃ for men with low-grade prostate cancer,” and we’re glad to see that HealthDay did not pass along those overly enthusiastic comments.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

There are options other than surgery or watchful waiting for prostate cancer (e.g. radiation). The story did not mention them.

Does the story establish the availability of the treatment/test/product/procedure?


Vitamin D is ubiquitous in stores, food and sun exposure, and that fact was made clear.

Does the story establish the true novelty of the approach?

Not Satisfactory

While the article successfully avoids promoting this research as anything resembling a “first,” it also offers no historical context. Of which there is plenty, including previous studies and inappropriate promotion of vitamins to men who fear or who have prostate cancer.

Does the story appear to rely solely or largely on a news release?


The article makes ample use of some of the language and information in the news release, but appears to have interviewed the researcher and an outside source to inform the story.

Total Score: 5 of 10 Satisfactory

Comments (1)

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James Hightower

July 31, 2015 at 11:30 am

I had a psa of 14,5, and 2 other psa tests after, which were close to it from 2 other docters that I see. One being a pain clinic for my lower back pain (inflamation in the vertabrae requiring steroid shots). If vitaman D helps with inflamation, which cancer loves, then I understand how my prostrate cancer became aggressive with a high gleason scale suddenly. Being agoriphobic and in my room, when I saw my doctor and did a blood test a few years ago, my vitami D was 9. I was given prescription of vitamin D to take once a week for 4 weeks to raise it. It was probably too late by then because the extremly low D let the cancer get a hold. That is my theory. I should have had a psa done every year, but you have to request it from your doctor, or they will not add it to your blood test until you are 55. A psa should be mandarory for males 40 and up when blood test is done when doing a physical, in my opinion.