4 ms·
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 s
by cjbillington 9y ago
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.
- bd 9y agoHard to tell much about B vitamin supplement effects on non-smokers from this study. 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).
- jxy 9y agoSome people hate statistics for a reason, and this is the exact reason. It is outrageous how the author conveniently manipulated the data to support the claim in their paper. For those of you who want to do your own analysis, assuming their data are authentic, take a look at their Table I: http://ascopubs.org/na101/home/literatum/publisher/asco/journals/content/jco/2017/jco.2017.35.issue-30/jco.2017.72.7735/20171005/images/large/jco.2017.72.7735t1.jpeg http://ascopubs.org/na101/home/literatum/publisher/asco/jour...
- bd 9y agoDigging deeper into tables in the paper, I realized there is actually even less data about non-smokers than I thought. 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%) http://ascopubs.org/na101/home/literatum/publisher/asco/journals/content/jco/2017/jco.2017.35.issue-30/jco.2017.72.7735/20171005/images/large/jco.2017.72.7735t3.jpeg http://ascopubs.org/na101/home/literatum/publisher/asco/jour... ----- 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.
- Legogris 9y agoI would also guess that smoker who experience health problems are more likely to start supplementing.
- BoiledCabbage 9y agoIsn't > 55 micrograms essentially anyone who takes a multi-vitamin? Maybe it's just denial as I take one, but this study is a bit hard for me to believe.
- bd 9y agoAmounts of vitamins per supplement seem to vary wildly. 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
- deleted 9y ago[deleted]