This study then showed, not just that people got cancer, but they got lung cancer. This study was not a randomized trial that can show causation: it was a cohort study, where they ask a bunch of questions about peoples' past or ongoing behavior and then look for correlations from which you can try to guess at potential causes.
In a cohort study, there are attempts to predict confounding variables and "control" for them, but this involves essentially assuming the result and backing out the math, and assumes you trust that the participant is giving you correct data anyway.
A really fun confounding variable you get in these kinds of studies is that people who even bother to do your study correctly are also people who probably listen to their doctor and brush their teeth and wear their seatbelts and generally lead a safer life. (I am forgetting the name of this, but it is something like "compliance effect"?)
Further, if you have participants who don't just answer poorly but actively lie in ways that are correlated with the variables you care about (maybe "another way I make myself feel better about my smoking habit is to pretend I smoke half as much as I do or also smoke cigars and not count them"), you are effectively going to have no hope of "controlling" for that in the way you can with a blinded randomized controlled trial.
Given this, I read this and only think "that's an interesting hypothesis that is now worth digging into with real science to figure out what is going on", not "OK, everyone should stop taking B12 supplements if they don't want to end up randomly getting lung cancer"... that is just way too specific and too predictable of a cancer to be associated with this particular supplement.
> 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.
Researchers themselves excluded never-smokers from more detailed stratified analysis because of their small number.
There were only 60 cases of lung cancer in never-smoker category (out of 36,381 people => 0.16%).
In comparison there were 748 cases of lung cancer in smoker categories (former + recent + current) (out of 40,737 people => 1.84%).
So there is 11.5x higher risk of lung cancer simply by smoking (including people who stopped smoking).
For comparison the highest hazard ratio from this study was 3.71x for a category of current smoker taking >55ug/d B12 vs current smoker who is non-user of B12.
Also curiously, the worse risks seem to be associated with people who stopped taking vitamins than people who currently use vitamins (B6: 1.97x vs 1.38x, B9: 1.65x vs 1.05x, B12: 2.58x vs 1.19x - individual supplement use status former vs current).
Plus smaller doses of B6/B9/B12 shown in this study to pretty much universally lower lung cancer risk by a bit (hazard ratios of 0.8-0.9x ranges; one noticeable outlier >600ug/d B9 in recent smokers halving risk of cancer).
For those of you who want to do your own analysis, assuming their data are authentic, take a look at their Table I:
Out of those 60 non-smokers with lung cancer apparently just 20 were men (out of 14,208 study participants who were men and non-smokers => 0.14%)
Curiously this also means non-smoking women have 1.28x higher chance to get lung cancer than non-smoking men (unrelated to vitamins).
For never-smokers vs smokers men risk ratios are then (again unrelated to vitamins):
- current smoker: 31.7x higher risk
- recent smoker (stopped < 10 years ago): 21.3x higher risk
- past smoker (stopped > 10 years ago): 8.9x higher risk
Take home message: stop smoking!
Precautionary principle: if you take B vitamin supplements, you can continue (for slight decrease of cancer risk), just make sure you aren't taking mega-doses (especially if you still smoke), but really - stop smoking - the sooner you do less cumulative harm you get.
Maybe it's just denial as I take one, but this study is a bit hard for me to believe.
Just from checking supplements I have at home:
Supplement #1 (all B vitamins):
- B6: 4.2mg
- B9: 600ug
- B12: 7.5ug
Supplement #2 (just B6 + B9 + B12):
- B6: 75mg
- B9: 800ug
- B12: 150ug
Recommended daily doses are:
- B6: 1.7 mg/day (men)
- B9: 400 ug/day in US, 330 ug/day in EU (men + non-pregnant-non-lactating women)
- B12: 2.4 μg/day in US, 4.0 μg/day in EU (men + non-pregnant-non-lactating women)
Tolerable upper intake levels are:
- B6: 100 mg/day in US, 25 mg/day in EU
- B9: 1000 ug/day
- B12: no sufficient evidence for setting upper level
From the study:
Beneficial effects (for men):
- B6: 1.41 - 3mg/day, multivitamins
- B9: 200 - 400 mg/day
- B12: 0.1 - 55 ug/day
Harmful effects (for men):
- B6: > 20mg/day
- B9: 400 - 600 mg/day
- B12: > 55ug/day
Also something to keep in mind: apparently the majority of people in this study who got lung cancer were heavy smokers for many years, even if they stopped smoking.
Lung cancer by years of smoking:
- 0 years: 60 cases
- 1-35 years: 169 cases
- > 35 years: 568 cases
Lung cancer by pack-years of smoking:
- 0 pack-years: 60 cases
- 1-25 pack-years: 178 cases
- > 25 pack-years: 555 cases
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.
Humans are so complicated but these studies try to boil them down to some simple cause and effect relationship.
The way I did this was by making it a bit harder/uncomfortable to get my cigarettes, and by tring to smoke just 1 cig less every period.
E.g. I would usually carry around a pack in my jeans, so I started leaving them at the car, so if I wanted to smoke it would be harder for me, so that would reduce the impulse when I was very busy or just didn't have the time. After some time doing that it was no longer a problem so I had to up the ante: I would only bring so many cigarettes with me and leave the rest at home. So if I knew I only had say 10, I would try to spread them over my working hours.
Then I would bring only 5 and so on. At some point, some 2 years later I would only smoke 1 in the mid-morning, 1 after lunch and 1 in the afternoon.
Then I would set myself to only have 1 after lunch. Then 1 every other day.
After that it was easier to go several days without smoking until one day I just didn't feel like buying more and I stopped.
Also, I think what worked quite good for me was to avoid "punishing" myself if for some reason I didn't make it one week and smoked a couple more, as long as I was kept reducing it overall the other weeks.
Doing it like this was easier for me I believe, because my own body was breaking the addiction so I just enjoyed smoking less and less, which I think it's why I couldn't do it cold turkey: my craving was stronger than my will. However reducing the craving over a long period allowed me to weaken that craving until my will to stop was stronger.
I know my method sounds a bit stupid if you phrase it like "how to quit smoking in 3 years", because everyone wants to do it NOW. But by avoiding such an unreachable (to me) goal, I managed to quit even if it took that long, so I am happy with the results :)
Hooe that helps.
Also for him he did the "don't break the chain" method. Bought a paper calendar, a pen, and a red and green marker. Week one was 8 cigarettes per day, week 2 was 7 cigarettes per day, etc. You write down that number with the black pen through the calendar so you know what your goal is. Exception being for 2 weeks you do 2 cigarettes per day, and for 3 weeks you do 1 cigarette per day because when it's that low you are fighting more of the mental aspect.
Then every day at the end of the day, exactly midnight you can put a a big green checkmark if you kept to the number, or a big red X if you didn't.
The idea is that you never want to break that chain of green checkmarks.
He hasn't smoked in a few years now. :)
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.
My doctor also instructed me to eat more red meat. Anemia runs in my family (on the feminine side) to the point where my mother has had to have blood transfusions to save her life. I'm a male with a similar problem to a far lesser degree. While I aim to eat enough iron-rich foods, to boost the absorption I was also instructed to up my B12 intake as iron has traditionally been understood to be a bit easier to overdo. Food was always recommended over supplementation as well, but it's often not enough.
I used to be a smoker. After quitting and having some tests done by my doctor he said that my lungs should be back to functioning/health as if I'd never smoked inside of 4-5 years (so long as I didn't relapse. That hasn't been a problem). We didn't discuss chances of lung cancer in spite of that. If it's true that the supportive effects of B12 supplementation even on ex-smokers exponentially increases chances, then it becomes even more concerning.
I'll be watching for developments.
"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."
No mention was made whether the participants had MTHFR mutations, perhaps because the cohorts started 20 years ago and cheap sequencing wasn't yet available.
All it tells is that more actual science needs to be done here. Also the article was classic poor science reporting with obvious bias.
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.
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.
I'm not connected with Genetic Genie, I'm only sharing a way I found to discover if I have the MTHFR mutation.
Also, what led you to your curiosity of MTHFR? Are there other services you use to “hack your health”?
As a side note: B12 is created by micro-organisms in the soil, making our vegetables and fruits completely covered of it. With our modern lifestyle, the soil is terribly poor of these micro-organisms and having cleaned-as-hell vegetables reduces even more the B12 we can find in these vegs.
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.
"Ruminants, such as cows and sheep, absorb B12 produced by bacteria in their guts"
Pre-seeded during breast feeding, as happens across all mammals. How many billions of years do you want to go back on this question?
> And are the bacteria killed off by the antibiotics they're given?
Evidently not, as in developed country sick animals don't get turned into meat foods on principle and by law --- so they don't show up deficient. If they lived for 9 decades like we do, they might (or not). But they don't.
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'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.
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.
here's what they give them:
Long-Term, Supplemental, One-Carbon Metabolism–Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort
Link only found among Men. 'Results from previous studies of an association of B vitamins with lung cancer risk are inconsistent.'
Or it doesn't exist, or it even lowers the risk of cancer in women, or ...
I hate when something "not found" in some study is streched to fit some specific tone that the article wants.
> Deficiency can also mean genes that should be inhibited are no longer inhibited, also potentially meaning cancer. Sufficiency of certain vitamins is important in cancer prevention, but avoiding excess appears to be similarly important.
Less Vitamin X today is not going to kill you. It's probably better than, "oh I need 1000mg so I'll just take 5000 and let the body handle it."
In 20 years of looking I've never seen a study that links recommended daily allowance amounts to anything harmful.
Yes 1000x RDA vitamins should be banned, but incendiary titles muddy people's thinking.
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.
I think there's another limitation in how much the liver can capture and process per day, and I don't know what that limit is, but it's higher. In any event, once it is processed (and after excess is eliminated), it is highly conserved in your body -- a few micrograms can last years, IIRC.
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.
The FDA has wanted to do something about this for a long time. They clearly see supplements as dangerous (especially things like 6000% RDA).
1. You can't advertise any benefit without having a clinical trial (funded by the company) showing that benefit.
2. A strict (every 6 months) inspection of manufacturing facilities.
3. You're required to list the ingredients, and the inspections make sure you're using them.
4. All known side effects are required (found during aforementioned clinical trials) to be listed.
By contrast, the FDA is specifically prohibited from applying these regulations to the supplement industry. Unsurprisingly, many studies have found that the companies involved don't even bother to put the active ingredients in the pills.
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.
Neither you nor the government should be telling me what I can put in my body.
> Why let people risk their health.
Because it's their health to risk, not yours.
Seriously, most people with a western, meat-dominated diet likely get sufficient B automatically.
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??