Vitamin B6 and B12 Supplements Appear to Cause Cancer in Men

But the article says:

> Among people who smoke, the effect appeared to be synergistic, with B6 usage increasing risk threefold. The risk was even worse among smokers taking B12. Using more than 55 micrograms daily appeared to almost quadruple lung-cancer risk.

> There was no apparent risk among women—which is not to say it doesn’t exist, only that it wasn’t apparent.

Which would appear to rule out smoking as a confounder, except until you realise that people who smoke more might be more likely to take vitamin B6 - maybe because they are actually diagnosed deficient and not just trying to make themselves feel better - and that maybe B12 deficiency might be associated with higher levels of smoking as compared to lower levels (if higher levels of smoking are required for B12 deficiency than B6 , and the deficiencies are similarly diagnosed and not just feel-good vitamin supplementation). i.e. "smoking" isn't a binary category.

And the gender thing would be really surprising if the cancer was only caused by smoking - unless we know that smoking doesn't cause B6 or B12 deficiency in women, then that would also appear to remove smoking as a confounder.

In conclusion, maybe.

Something else that seems to be overlooked here is that the cohort were folks who already had heart disease. Since smoking is heavily correlated with poor cardiac outcomes, I imagine a significant swath of that 6,837 cohort were likely to be smokers.

Even if they aren't smokers, taking an already sick test group and trying to draw general conclusions about certain inputs is madness. Epidemiology can be a great way to form hypotheses, but this entire discipline of research has been misapplied for the better part of a century now.

This is obviously my own anecdata, but up until about 2 years ago I smoked for close to 20 years. I've never once heard that B12 did anything to prevent cancer. No smoker I ever interacted with - and I interacted with thousands over the years I'm sure - has ever said or implied they took vitamins to offset their tobacco use.

Another issue is, they don't seem to differentiate between which B12 supplement. Cyanocobalamin may or may not have long term effects, and probably should be avoided as a supplement ingredient.

Although, someone always pops up and says "but there isn't enough cyanide to matter"; we don't know what supplementing with cyanocobalamin does over a decade actually does.

How many smokers are health conscious enough to know that they have a B12 deficiency but not health conscious enough to quit smoking?

Lung cancer doesn't just affect smokers, though. People who have never smoked still have a lifetime risk of about 0.5%-1.0%. And the study was studying self-reported non-smokers in addition to smokers.

"We found that B6 and B12 had sex- and source-specific associations with lung cancer risk. In addition, the association in men was more pronounced in cigarette smokers."

http://ascopubs.org/doi/full/10.1200/JCO.2017.72.7735

Same aplies to drinking beer.

This really needs to be at the top. It is something 40-60% of the population have MTHFR mutation. Given the size it is kind of surprising the marketing departments haven't started touting MTHFR safe foods on their packaging.

After learning about it from my 23andme results I now avoid regularly eating foods with added folic acid and take a supplement which can't be found at the grocery store because they will sell the lab created variety which can't be processed. After these changes various symptoms I have had all my life went away. But I can only guess what would happen if someone with MTHFR were taking the lab versions supplements every day for years.

Thanks for pointing this out. It was the first thing I thought of after seeing the headline. I have family that mentioned they have a MTHFR mutation so I checked my 23andme results through genetic genie and I did indeed inherit a mutation from one of my parents.

I changed multivitamins to one without folic acid and supplement with methylfolate and methylcobalamin.

I feel like it has helped a bit, but not exactly sure. I am still experimenting with the amount of methylfolate I use. I think if I want to take is serious, I need to cut out caffeine completely. I definitely notice stamina issues when I drink coffee and take methylfolate. Caffeine also prevents B12 absorption with kind of defeats the point also.

I would definitely like to see more research done as it all kind of feels uncertain.

If you use 23andMe, you can get a methylation analysis here: https://geneticgenie.org/methylation-analysis/

I'm not connected with Genetic Genie, I'm only sharing a way I found to discover if I have the MTHFR mutation.

Not only that, but B12 isn't actually produced by any of the animals which make up those "animal products" which allegedly have "plenty" of B12 in them. The animals, if they have B12, get it from eating vegetables which have bacteria on them.

These days, however, many animals destined for the dinner table are pumped full of antibiotics (which may kill those B12-producing bacteria), are fed other animals or sterilized grains/vegetables. So it is quite possible that the animals themselves aren't getting adequate B12, and as a result even animal eaters might have a B12 deficiency.

My own doctor recommends all his patients, whether or not they're vegetarian, take B12 supplements.

It is interesting that B12 in sufficient quantities is actually made by bacteria in the gut, but as it is not absorbed there (only small intestine can absorb that) it became a waste. It is probably one of the reasons that animals like dogs or gorillas eat their feces.

[1] http://www.veganhealth.org/b12/animal

My Crohn's disease impairs my ability to absorb nutrients, and so my doctor has instructed me to supplement several things, including B vitamins and calcium.

In the past he's given me prescriptions for these supplements, but these are vastly more expensive than the equivalent OTC versions (and yes, I've checked that it really is the equivalent molecule). So I'd hate to see new regulations that would increase my expenses just because some people believe in some kind of voodoo nutrition contrary to best practices.

I'm a single data point in this story.

I've been vegan since 1991. I also have Crohn's disease.

I had a bowel resection in 2001 and subsequently my B12 blood tests revealed a deficiency. I was then prescribed a course of monthly B12 injections. These went down to 3 monthly and for the last 5 years my yearly blood test have deemed them unnecessary.

However, I now have Vitamin D deficiency instead. Plus ça change.

Its worth noting that there are people who have b12 absorption deficiencies. My family has a history of it and a few are prescribed b12 injections once a month.

These injections are usually much higher than what you would take in pill for, as your body absorbs it easier and stores some for later.

Would be interested in more real science about the injections.

most factory farmed animals get their B12 from an injection

More likely that long-term consumption may be unhealthy for you due to the elevated levels of Red Bull sugar-free you're getting.

Try water.

Alternative milk types(soy,rice..etc), breakfast cereals also have a lot of B12 supplemented

I'd be more worried about the caffeine, which we know increases demand for calcium and magnesium, and causes an increase in water excretion, among other negative effects.

I'd be more concerned that you are basically drinking poison.

IMO, Likely just statistical noise, but clearly worth further study.

Link only found among Men. 'Results from previous studies of an association of B vitamins with lung cancer risk are inconsistent.'

Go about your day. This is not at the level of certainty to be actionable.

Tim Spector's book The Diet Myth: The Real Science Behind What We Eat has a chapter on B12 deficiency in vegetarians. He anecdotally found using himself as a trial that he couldn't retain B12 in blood level tests while on his usual vegetarian diet despite taking large amounts of supplements. He had to get injected B12 to get the same levels in his blood that consuming a rare steak once a month would provide. From a geneticist's viewpoint he ponders if this is some kind of trait left over from evolution. It's a good book if not 'over-written' meaning way too many flowery and very long anecdotes shoved into the research. He has a chapter on 'Vitamin supplement X causes cancer' studies as well.

By vegetarian do you mean vegan right? I have been an ovo-lacto vegetarian (commonly referred to as "vegetarian" in the US) for 15 years, have never taken any supplements, and my b12 levels are perfectly fine.

In general terms, I agree. Since B vitamins are mostly water-soluble[1], generally it has been assumed that excess would be excreted, and research that suggests that some of them are not so harmless is news.

1: https://en.wikipedia.org/wiki/Vitamin#List_of_vitamins

You're confusing milligrams (mg) and micrograms (mcg or µg). The recommended daily intake is a few micrograms; those tablets contain 1000 times that amount.

The reason people take 1000x plus etc is often due to absorption issue.

Many people have problems absorbing B12. That's why they have a deficiency to begin with. In order for these people to get normal B12, it requires extreme doses just for their bodies to absorb normal amounts.

There is little evidence that "a lot of supplements" are doing more harm than good. That is speculation. If you search pubmed there are thousands of studies looking at potential benefits.

However, if you are going to regulate based on real evidence of harm, then you would do the same for fast foods. There we have substantially more evidence of harm than we currently have with supplements.

Or we could decide to live in a free country and stop criminalizing what people decide to put into their bodies of their own free will. We are trending to free access to marijuana, I would find it ironic to then start restricting supplements.

April 22, 1976, Cogress passed an act prohibiting the FDA from doing just this and in 1996 additional legislation resulted in vitamins being classified as food, not drugs.

The FDA has wanted to do something about this for a long time. They clearly see supplements as dangerous (especially things like 6000% RDA).

I think it would be better of the goverment just let anyone eat or take anything they want. Though they should fund extensive research into food, vitamins, home remedies, etc. and publish them in easy to understand guides and warnings. This could empower the people to protect themself.

BigPharma would love this.

Why stop there though. I think we should require a prescription. You shouldn’t be putting stuff into your body without medical supervision.

I’d even consider it for Foods heavy in certain vitamins. Pineapples have a mega load of vitamin c. Put those behind the counter as well. Why let people risk their health.

Wait: this was downvoted??

I can understand down voting snark and off-topic comments.

I can understand (though disagree with) down voting unpopular opinions.

But this is simply a comment (well, two comments) on sources of B vitamins in the human diet.

I know complaining of down voting is itself poor form, but really??

vegemite contains almost no B12.