I'm starting here a discussion on which dietary(/lifestyle intervention to adopt for healthspan and longevity when faced with discordant opinions, articles, studies.
I beg your pardon if I'm posting this in steps or installments, taking advantage of spare moments of quiet.
So, the scientific papers, even those in credible journals, often tell us things which are one the opposite of another. Also, advocacy, fanaticism, vested interests, academical interests may govern the content of a paper. The sheer size of these papers is such that even specialists sometimes hire teams of people who select the relevant info. Last, if we hear the experts, their opionions on some issues are very discordant. What to do? Is dr. Greger right or perhaps Dr. Mc Dougall is better, or maybe Dr. Fuhrman beats them all but Dr. Ornish is the most authoritative, on the other side people have had very good results heeding Dr. Attia or Dr Rosedale and Dr. fung, the advocates of low carb and keto diets which suggest just about the opposite of the 'vegan doctors'.
One possibility is the adoption of Bayesian inference
First step is usually to assign a value or distribution to the a priori function, P(H), our starting point, what we know on the subject.
for example, the subject, not a banal one, could be beneficial or detrimental effects of the ingestion of fresh fruit (250 to 750 g daily).
We may at the beginning restrict the subject to apple and oranges. If I eat apples or oranges, am I going to benefit or not or even am I going to get sick?
So, first thing I would hypothize a benefit function (BF) with values ranging from -1 to +1.
BF= -1→ apples and oranges are going to be 100% detrimental
BF= +1→ apples and oranges are going to be 100% beneficial
BF=0 → apples and oranges are irrelevant to health, not detrimental nor beneficial
BF= -0.5 → 50% of probability that fruit is detrimental
BF= +0.5 → 50% of probability that fruit is beneficial
And so on....
The BF is just a simple way to assess quantitatively the degree of benefit or detriment that our food or intervention will deliver.