Megadoses of Vitamin D have no effect on prostate (or any other) cancer

My pcp told me the same thing last week. He said some recent studies can’t even determine just how low is low but it’s lower than once thought. “too much can make ya sick and if I’m gonna take it, monitor it.”

I quit that day. An internist put me on it a year ago.

It is interesting and also somewhat disturbing to learn over time that our doctors don't know any more than we do about these supplemental treatments. A half-dozen years ago my primary care doc recommended I take fish oil, which I soon discontinued after the studies showed it added no benefit to heart health and might actually be detrimental for prostate cancer patients. A couple of years ago my RO recommended high daily doses of vitamin D3 which I declined to do because I was skeptical of its potential benefit and understood it could increase incidence of kidney stones.

That is interesting. I've always doubted the effect of vitamin D.

I have throughout the years tried supplements, after reading something and then sometime later stopped always remembering one doc who said generally it won't hurt you and it just makes expensive pee!

I choose to manage my diet which has clear evidence of impact on health.

Cigafred-

As I mentioned in the blog, there have been inconsistent results from observational studies, like the one you mentioned. In fact, if you follow the links in my blog, you will find examples of studies that showed a harm to supplementing Vitamin D, a benefit, and no effect. That's why this study was so important - it was a randomized clinical trial (RCT). RCTs are considered to be the highest "level of evidence" and it trumps all studies like the one you cited.

You can hardly get more evidence than a level 1 study.
Also this quote looks like a good argument for giving up on D for men with PCa.

Tall Allans blog said...
Vitamin D may prevent early growth of prostate cancer but may accelerate metastases

Vitamin D is a potent hormone (like testosterone) and we maybe should not take light of its effects on PCa cancer cells? Not all effects will be positive, I assume.
A mystery if US doctors recommend it for PCa patients.

DJBearGuy said...
Dr. Brooks at Stanford told me he used to do research on diet and prostate cancer. But there were so many conflicting results that he gave up and got out of that field.

Good thinking! Very hard to publish on the relationship between nutrition and oncology that is not junk science. And without publications, tenure at Stanford U is out of the window.

Post Edited (Sr Sailor) : 7/23/2018 4:47:05 PM (GMT-6)

I do wonder why they would choose to give a staggering 200K IU's followed by 100K per month. Sounds exceedingly Un-physiologic, considering I think about the most you can get from sunshine in one day is about 10K, and normally a lot less than that? Could harm actually be done in some unknown way with such a staggering 1 time dose, then not any more until next month? As oppose to a few thousand a day? I don't know, maybe. But at least it shows that even staggering doses do no harm, at least for anything they were looking for, or at least as far as any cancers they were looking at. Imagine if you decided one day to take 100 pills of 2000 units! Still, no apparent U shape curve I guess? The HR was no better, but also no worse? Is that right?

I have wondered before why, as they rarely do a study period, why when they do, they do one in what seems a very odd way, such as a 1 time dose of 200K. Like when the guys up in Canada did the vit D RCT on kids for colds(later repeated in almost the exact same way in China), announcing "no benefit". But did they do a plain old Placebo? Of course not. Their idea of a placebo was a lower- but still way more than adequate for small children- dose of Vit D. So though their conclusion was"no benefits to large dose", we are not told anything about whether the already large(but smaller) dose had significantly lowered the incidence of colds. Because if you got a significant reduction- maybe even large reduction- from the 1st dose, how much more would you really expect from an even larger dose?

However, in both studies, almost hidden in the small print(you had to dig for it, the headline was "no benefit for colds"), was an additional Flu reduction of 50%. I.E., another 50% on top of whatever the smaller dose may have already provided. (and compared to last years flu shot of what? 10% effective?) A FAR greater benefit than provided by flu shots most years. But no need to put that in their head line, I guess. Sometimes I just wonder why they decide to do some studies in the fashion that they do, leaving things unanswered that could have easily been answered(like was there a benefit compared to placebo, or at least compared to zero supplementation?). Such actions can not help but make me wonder if their biases are the reason why. But no doubt they have their good reasons, and it is just all over my head. Regardless, I found an additional flu reduction of another 50% over whatever the smaller dose might have provided worthy of mentioning in a prominent way, even if they didn't.

There has also been an interesting RCT on vitamin D vs diabetes. Also, a very interesting study with breat cancer. NOT an RCT of course, but still very interesting considering that there was a straight line improvement for each 10 ng increase up to 60 ng. Which begs the question: how do you get to 60 ng with out either LOTS of sunshine or supplementation? I need to go back and add that study to my thread on Vitamin D vs diabetes.

Tall Allen said...
This constitutes Level 1 evidence, which supersedes all others.

Understood. Very well understood, actually, drawbacks and all.



Peter, the greatest risk of “megadosing” is those who take very high levels outside of a doctor’s care, and/or without knowing & monitoring their levels regularly. I’ve heard of some crazy, out of control situations where people were following the mantra “more is better,” and doing so totally blindly and on their own. That is, in my opinion, a terrible mistake.

100,000 IU per month is equivalent to a daily average of 3,333 IU per day. Vitamin D is stored in fat and the liver. so a big dose stays in the body for use as needed. That's why it doesn't matter if you take a bigger dose less frequently or a smaller dose more frequently. They felt that they would get better compliance with 1 pill per month, and they did. They randomly did blood tests on men in the study and found that serum Vitamin D blood levels consistently increased by at least 20 ng/ml.

Your analogy with propofol doesn't work. Vitamin D has no sudden effects, other than to draw calcium out of bones and into the serum. It is held in storage to be let out into the serum as needed. That's why it takes so much to measurably raise serum levels. 100,000 IU only raised serum levels by 20 ng/ml - your body controls how much it lets out into the serum.

For BB and others who obviously don't understand the concept of levels of evidence, here's a good starting point for learning about it:

/www.cebm.net/2009/06/oxford-centre-evidence-based-medicine-levels-evidence-march-2009/