https://www.cancerresearchuk.org/health-professional/cancer-...
From the page you linked to: "13% of bowel cancer cases in the UK are caused by eating processed meat.
Bowel cancer risk is 17-30% higher per 100-120g/day of red meat intake, meta-analyses have shown.
Bowel cancer risk is 9-50% higher per 25-50g/day of processed meat intake, meta-analyses have shown; however bowel cancer risk was not associated with processed meat intake in a pooled analysis of UK case-control studies. Colon cancer risk is 12% higher per 1mg/day of haem iron intake, a meta-analysis showed; though bowel cancer risk was not associated with dietary iron intake in a pooled analysis of UK cohort studies.
Serrated bowel polyp risk is 23% higher in people with the highest versus lowest levels of red meat intake, a meta-analysis showed."
https://www.cancerresearchuk.org/health-professional/cancer-...
lifetime_risk_no_meat = 0.07
lifetime_risk_yes_meat = 0.07 + (0.07*.3)
risk_of_death_given_cancer = 0.25
(lifetime_risk_yes_meat - lifetime_risk_no_meat) /risk_of_death_given_cancer ==> 0.084
So an 0.084% increase in risk of death if we use the most risky scenario available.
[1]: Lifetime risk of bowel cancer https://www.cancerresearchuk.org/health-professional/cancer-...
[2]: https://www.cancerresearchuk.org/health-professional/cancer-...
[3]: Persons-> Crude rate -> UK https://www.cancerresearchuk.org/health-professional/cancer-...
lifetime_risk_no_meat = 7% lifetime_risk_yes_meat = 7% + (7%30%) = 9.1% risk_of_death_given_cancer = 25% (lifetime_risk_yes_meat - lifetime_risk_no_meat) risk_of_death_given_cancer = 2.1%*25% = 0.00525 = 0.525%
So by this math, eating a quarter pound of red meat a day causes men in this worse case scenario to die 0.525% more often, which is a sixteen times higher rate than your calculated value.
Of course, that’s not how to actually do the relevant calculations, since (assuming no significant technology changes), everyone will eventually die. Thus you instead need to do calculations based on life expectancy, or better yet on QALY (quality adjusted life years), which adjusts for the quality of life that people live in addition to their age.
I was generously assuming that if I follow their advice, I eliminate bowel cancer risk entirely. Since only .074% of the population has it (74 per 100k), that’s the max change in risk of death.
But you’re right, I really only decreased my risk by 13% of that .074% by eliminating red meat. Still don’t see the enormous upside.
>This is because there is probably a link between eating a lot of red and processed meat, and bowel (colorectal) cancer.
Probably? Link? "Link" as in "co-occurring but not necessarily causally related"? No references to the studies or methods? This is the same quality material that has been used to promote eating less fat for several decades, while obesity exploded to record levels.
It’s a bit ironic you are questioning the study with regards to causality and then mention obesity exploding to record levels with an unsubstantiated, implied connection to the promotion of eating less fat. Your coment would have been perfect without the obesity comment since your comment is decrying linking things without sufficient causal evidence.
1. There was a campaign against eating fats.
2. There was an obesity epidemic that started shortly after the campaign against eating fats.
Fact 2 is seductive because it’s natural to assume that 1) is the cause. But without further analysis and study one can’t conclude this. In a post decrying causal links without proper statistical evidence it’s ironic to fall victim to this seduction without proper statistical evidence.
That's all I am saying.
The previous recommendations (that got retracted) had "convincing" evidence at their time too.
Then I found that my total cholesterol was v high (7.5 mmol/L). I got scared and followed my doctor's dietary advice (less saturated fat, basically), and it dropped significantly (to 5.7, still higher than recommended levels)
That's when I realised that the likelihood that I can come up with some health strategy for myself that is better "following the advice of professionals" is extremely low
Then I woke up one day with the feeling that this can’t be right; started experimenting, and within a couple of months got to 5k, and within less than a year to 15k, feeling much better all the time and with every objective measurement improved.
That’s when I realized I should look into things and not just trust “advice of professionals” most of whom follow others quite blindly, and whose incentives are very different than mine (in my case, their incentive that guided me for 20 years is to minimize their legal risk - it was not to improve my health).
I agree it is important to know the bounds of knowledge - both yours and the professionals - and also to realize the incentives.
Also, google “John ioannadis”, an MD, on nutrition science and research in general. His seminal work about not trusting published research is unrefined 13 years later.
Fox News will wheel out anyone with a PhD who is willing to cast doubt on climate change, Vox will dredge up someone who'll say that NASCAR gives you cancer and we all end up less informed than grade-schoolers.
Scientists are largely powerless to "push back" against anything, because they don't control the institutions that disseminate information.
It also turns out that validating people's preconceptions and getting grants is a great way to build credibility via "social proof".
The truly skilled PIs can develop a popular idea, make it accepted in the field, then dramatically disprove it once the "bad" researchers start piling on! These masters can usually be identified by massive grants, sending students places(careers) to build relationships/incur debt of favors over years, writing bestseller books (ghostwritten) etc. And these are the people whose ideas everyone repeats.
It doesn't necessarily follow that people will gamble grant money on the off-chance that you might turn out to be that superstar.
One of the points made by Ioannidis is that we’re far too easily swayed to believe what sounds plausible when no one has yet asked “Could this be for some other reason altogether that we aren’t testing for?” and then tests for those reasons. That flaw applies here: studying just one community automatically implies that the results are invalid, simply because there’s no evaluation of other communities that share various attributes that could be hidden factors for the benefit.
EDIT: Per one article, that study “would try to cut through the stories and establish the facts about Ikaria’s longevity”. It has succeeded in establishing that, factually, Ikaria’s longevity is a thing relative to other populations. It has not established which of the properties of Ikaria are responsible. (For example, perhaps the island is slightly radioactive, and old people thrive in a slightly higher radioactivity.) Extrapolating that their diet is responsible is an instance of the A/X error described in the above-linked article.
> Conclusion. Modifiable risk factors, such as physical activity, diet, smoking cessation and mid-day naps, might depict the “secrets” of the long-livers; these findings suggest that the interaction of environmental, behavioral together with clinical characteristics may determine longevity. This concept must be further explored in order to understand how these factors relate and which are the most important in shaping prolonged life.
It could be that the quantity red meat is solely responsible for their longevity, or has nothing to do with it, or plays some role with the many other confounding variables.
The organisation said the evidence that red and processed meats are causes of bowel cancer is convincing. It advises that people eat no more than 500g of red meat a week (around 70g a day) and avoid processed meats.”
https://www.nhs.uk/live-well/eat-well/red-meat-and-the-risk-...