I mean, if you click on the first link you will open the paper they are summarizing[1]. It's a meta analysis of 64 studies, so you could certainly go through the studies and look at each population.
However, the actual answer is that all population studies are only gross generalizations that may not apply to you. They are often quite useful because the odds are generally good that they do apply...but it's never certain. Even if you are a member of the studied population your specific circumstances may overwhelm your populations norms.
Yeah, but I am at the tail end of these statistical curves and my life was absolute hell and doctors (but one) did nothing for me. And they kept telling me to eat fiber cause my cholesterol was so high and HDL was too low (30)!
If the meta analysis showed population differences, why did the article not bring it up? This is what is wrong with nutrition research, then never account fro genetics despite the huge about of evidence that it is extremely importnat.
The truth is that fiber does not reduce mortality for everyone by 23%. I would rather not be guessing with science and health. I lived through that and it took me years to get out of it.
However, the actual answer is that all population studies are only gross generalizations that may not apply to you. They are often quite useful because the odds are generally good that they do apply...but it's never certain. Even if you are a member of the studied population your specific circumstances may overwhelm your populations norms.
[1] https://pubmed.ncbi.nlm.nih.gov/38011755/