Just something I randomly found in a search.
Every 10g per day is correlated with a 10% reduction in all cause mortality (up to 30g). Mostly from a reduction in cardiac and cancer deaths.
Use a conventional search not an ai-generated summary as that will have influencer slop mixed in. Though oddly, I’ve never seen an anti-fibre influencer, but have seen lots of pro-fibre influencer posts!
FWIW, the evidence demonstrating that fibre is protective against colon cancer is limited, and when studies try to adjust for behavioural differences, the colon cancer reduction disappears.
Actual RCTs that randomly assigned subjects found no difference in polyp rates between high and low fibre diets.
For decades it was indeed widely observed that the people who ate a lot of fibre tended to have a lower incident rate. But the sort of person who has a high fibre diet almost always has a lot of other protective habits and norms: They're less likely to smoke, less likely to drink to excess, they tend to eat less red meat, they eat less sugar and UPFs, and so on.
As is often the case, these habits don't tend to happen in isolation, and this is where observational studies fail. So if you take someone with a lot of bad habits and supplement fibre, they'll have better cholesterol control, glycemic benefits, and of course regularity benefits, but it won't measurably move the needle on colon cancer rates.
This is all just conversational, but the current consensus is that fibre, or lack thereof, is not a contributor behind the rise in colon cancer among younger subjects. There are many suspected causes, all moving the needle enough that incidence rates jump.
As far as I know the only RCT that fits that description is one looking at people who had already developed adenomas and then tested for reoccurrence.
An RCT actually designed to answer the question would need to last decades and just isn’t feasible.
There are a large multitude of studies that show a negative correlation between CRC and fiber intake even when adjusting for diet, exercise, BMI, income, alcohol consumption etc…
> but the current consensus is that fibre, or lack thereof, is not a contributor behind the rise in colon cancer among younger subjects.
There’s not good evidence to say it’s the sole or primary factor, but saying there’s consensus that is not a contributor is way too strong.
In most cause hypotheses, fibre just doesn't rank at all. I mean, of course everyone should eat more fibre so that's good, but it isn't a credible cause for the rise of colon cancer rates.
Most destructive to the fibre hypothesis is that fibre intake has actually increased over the past few decades, at the same time that youth colon cancer rates crept up[1]. I don't know what notion people have about common Western food practices decades ago, but in the 1980s, for instance, fibre was basically non-existent in the common diet: No one ate multigrain anything. Everything was loaded with sugar, trans fats and simple carbs (we literally considered that healthy, with hilarious products like Snackwells).
[1] Twice as many young people, per capita, are facing colon cancer now than in the 80s. Overall colon cancer rates are down significantly now, however this is most certainly due to the massive reduction in smoking and other behavioural issues that catch up to you after many decades, but kids today are in no way eating less fibre than kids in the 1980s.
> There are a large multitude of studies that show a negative correlation between CRC and fiber intake even when adjusting for diet, exercise, BMI, income, alcohol consumption etc…
Not really. Take any behaviour or practice that is common among the healthier cohort and it's easy meat for bullshit study results. It's why the nutrition field in particular is full of contradictory studies because "adjusting for" is carrying a lot of unmerited credibility.