> This relationship remained significant when influences of caloric intake, urbanization, obesity, education and carbohydrate crops were statistically controlled.
In other words, they did not control for wealth or income, which quite obviously confound this entire exercise. Probably this paper is actively worse than useless.
This is the problem with almost all nutritional studies. They’re almost always based on correlation. But human life has millions of facets, and each facet is correlated with thousands of other facets. It’s nearly impossible to discover a causal relationship between two lifestyle variables unless the effect is very pronounced.
So, we can't know trans fats are bad nor any other facts that you take for granted? What about smoking? I don't think people who say this realize the bullet they would have to bite. Though I only seem to hear it from people who are about to reject scientific consensus on something that's inconvenient for them because they like the taste of certain foods, like butter.
> It’s nearly impossible to discover a causal relationship between two lifestyle variables unless the effect is very pronounced.
Also, for many things (like smoking), we have established causal relationships by explaining the mechanism of action. E.g. cigarette smoke damages DNA, lead poisons the brain leading to neuron death, etc.
The fact that you can pick up on negative effects through observational studies if they are large enough makes me especially suspicious about results that differ from study to study. Perhaps there is an effect there, but if we can't reliably pick up a signal, maybe it's not something I need to worry about.
What effect size is big enough for you to worry about? A quick google search shows that smoking reduces life expectancy by 5-13 years depending on the study. Let's say that for smoking, the 'true' reduction of life expectancy from smoking is somewhere in the middle, 9 years. Then, the study I found with the 5-year estimate, is wrong by 4 years.
So, for some lifestyle change to reliably be reproduced by observational studies, it would have to be a 'true effect' of 4 years. I would say that 3 years, or even 1 year, is something to worry about.
Oh no, the evidence is clear when it comes to smoking. What I was trying to say: Smoking is a nice reference point to orient yourself around, because you can fairly confidently conclude that it's very harmful even with imperfect methods. So we can pick up on large negative effects using imperfect tools. At the same time, when you apply the same imperfect methods to other objects of study (e.g. the impact of coffee on health), you often get much more inconclusive results, which change from study to study. In that case, I don't think there is much sense in worrying until more robust methods can find clear evidence.
the real problem with these studies is the critics. If it's a study that says veganism is good, then everyone does that or has a moral imperative for that to be true will come out and say "what more do those evil meat eaters want?" while simultaneously the meat eaters will lambaste the study as worthless on any point they can find.
Of course, the situation works in reverse. The problem is that it's incredibly difficult to find genuine, unbiased, nuanced criticism of diet research. Some people are dumb enough to see research that actively admits to funding from some food industry and immediately they say "this study is total bullshit" which is just not how science works.
It would be interesting to see stats on how education vs income relate to meat consumption, since education seems to also correlate with adhering to a plant-based diet by ethical choice (concern for climate or animal welfare).
> This population-based study, using data collected by the United Nations and its agencies, tests the hypothesis that, worldwide, populations with more meat consumption have greater life expectancies.
With the caveat that I'm not familiar with the data sources and methods used in this study, it sounds to me like what it shows is not so much "eating meat is good for you" as "living in a country where people eat more meat is good for you". Which I think is a pretty significant distinction when the potential confounders include virtually everything that affects the price and availability of meat relative to vegetarian foods (infrastructure capacity and robustness to support CAFOs and regulation/monitoring of such to avoid disease/contamination, access to international markets, political stability, monetary policy, agriculture subsidies, etc.).
I'm not saying that there can't be a nutritional effect. I suppose it's entirely plausible that, as the authors suggest, some of the correlation is explained by trace mineral and B12 intake. I just don't see how this particular study does much to establish support for such an explanation.
(Disclosure: I find myself pretty biased against this study because some of the wording is burying the needle on my personal paleo-woo-bullshit meter. For instance, the authors refer to "unique nutrients from meat" in what I read as a non-hypothetical way, and I'm reasonably sure such nutrients have not been shown to actually exist unless the definition of "meat" is expanded to include dairy and egg products.)
This isn’t a study that tracked individuals, they looked at population level aggregate statistics.
They attempted to predict average life expectancy using linear regression with just a seven, yes only seven, population level statistics. Wow I’m so surprised they found average meat consumption was predictive… not. I just wasted my time skimming that.
I am going to guess that 100% of the meat eaters commenting here haven’t died since birth, which is an awfully good track record!
I love the intent of these kinds of papers, but at this point in time (2024 now!), surely there are resources for definitive studies, identifying every possible confounding variable.
Or a series of coordinated papers between researchers, progressively identifying every non-causal correlation so they can be taken into account.
Otherwise, we just get tantalizing paper after paper with its own mix of unaccounted for confounding factors and conclusively ambiguous correlations.
> I love the intent of these kinds of papers, but at this point in time (2024 now!), surely there are resources for definitive studies, identifying every possible confounding variable.
> identifying every possible confounding variable.
That part is meant aspirationally, as the point on the horizon we productively get closer too.
For one of the most basic issues in all of medical science, being thoroughly organized and funded could eliminate the costs of a vast growing body of less organized, lower quality work.
Uhm, now do the same for alcohol consumption. And for xanax consumption / number of tattoos per person / number of electric vehicles / number of TVs per person ...
Yeah this paper is garbage so many things would have a big influence on average lifespan - strength of workplace safety rules, smoking and alcohol use, driving mortality, regional conflicts, endemic diseases, etc etc that they didn’t include.
It’s particularly bad as an important conclusion they cite is that not including the variable they studied would lead to inaccurate modeling - while not including a ton of important variables themselves.
Maybe they did include some additional ones at first but removed them to the laughable 7 in order to get the result they wanted.
And in asia where there’s countries with large vegetarian but relatively wealthy populations they find the meat correlation doesn’t exist. Oh wow fancy that.
> People on vegetarian diets may be able to maintain “health” because they avoid potential meat-related nutrient deficiencies through one or more of the following ways: 1) Taking meat nutrient replacements to meet essential nutrient needs.
> The underlying reasons may be that meat not only provides energy but also complete nutrients to human body.
It seems that these issues can be addressed by modern vitamins and supplements. I've heard that you can be just as healthy as a vegetarian as long as you're still getting the necessary ones from another source. Another user (zhivota) mentioned the article not accounting for wealth or income, which can certainly limit access to the alternatives.
Considering this and the many meta studies deducing that veg based diets reduce all cause mortality, is this contrary to earlier research, or is this measuring some other thing?
The paper cites some big studies in refs 18-20, IIRC.
The big Australian study (ref 20?) did not found a difference in life expectancy between vegs and meat eaters.
And there is the big EPIC Oxford study with the same result (resp. all cause mortality).
I'm quite sure, that you will find a positive correlation of meat consumption vs life expectancy in societies with general deficient calories intake.
I feel it would be more useful to actually focus on data in a smaller, more homogenous group like people of similar incomes in a single country. The role that meat plays in the lives of people around the world is too varied (for example, wealthy upper-caste Hindus make up most vegetarian Indians).
I always found it odd comparing "group that scrutinises their food intake to some significant degree" against "everyone else".
I eat meat, but my diet and health is vastly different from somebody that eats fast food and processed meats.
> The relationship trend was observed in the WHO regions except in SEARO
So basically the trend was observed everywhere except the region which contains pretty much the only country where a significant population is historically vegetarian due to culture and religion.
Instead, here's an obligatory PSA to eat your lifestyle and social responsibility "vegetables": industrial meat agriculture is undesirable for 6 factual reasons.
0. Opportunity cost: It's an inefficient use of capital and resources that could be more effectively spent producing a greater volume of calories and nutrition as crops.
1. Pandemic evolution at the agricultural worker<-->CAFO<-->wildlife interface.
2. Antibiotic resistance evolution of harmful pathogens.
3. GHG emissions driving a large fraction of anthropogenic climate change.
4. Vast amounts of air, water, and soil pollution. (Ever seen or smelled a hog farm spraying liquid shit into the air over a waste lake?)
5. Meat agribusinesses from farms to meat processing plants exploit undocumented people, including children too young to legally work, in dangerous and sometimes slavery-adjacent conditions. In fact, meat processing plants advertise salaries in Central and South American newspapers precisely to increase the number of workers they can hire illegally and exploit. Undocumented children are exploited in foster care by being put to work illegally (too many hours, too young) where foster parents take some or all of their wages, or accept kickbacks.
(It's a terrible reason to list animal cruelty because no one cares as evidenced by their actions as most people are willing to pretend animal suffering doesn't exist if they don't see it and they get their tasty Big Mac out of it. And too many people will violently argue "MEAT is required for life" and will often present a cacophony of tired, false, dogmatic nonsense to justify their high-consumption lifestyle choices.)
"The Mediterranean diet permits the consumption of meat; however, it emphasizes moderation and lean sources. Poultry, such as chicken and turkey, and fish, particularly fatty types like salmon and mackerel, are preferred, while red meats are to be enjoyed sparingly and in smaller portions." https://mediterraneandietguru.com/can-you-eat-meat-on-the-me...
BTW people who use the Mediterranean diet tend to live long, healthy lives.
> BTW people who use the Mediterranean diet tend to live long, healthy lives.
They also tend to walk a ton and the portions are vastly smaller.
Is it the "Mediterranean Diet" or "Living in Italy" that causes the difference?
We joked about members of our vacation party who would have first, second and third gelato for the day. However, totaling that all up was still less than a single sitting of gelato in the US. A slice of cake was 3-4 bites and not an eighth of a 9" pan. etc.
^ This is key... I live in a "blue zones" area and it is apparent to me that you can't cargo cult this stuff, IE: it isn't a matter of just copying one part of it, but all the pieces that work together. And, even if you account for all the lifestyle stuff, genetics can still get you. So much emphasis is put on the food part of longevity, but I'm convinced that stress and lack of community (IE: loneliness) are just as much of a problem in overall health.
And if we're talking about centenarians in blue zones, we also have to account for recovering from world war 1, world war 2 which introduce famine and "accidental" deaths
Not to pick on your comment but could you share which Mediterranean diet relies heavily on turkey? Chicken for sure, fish for sure (not lake-grown farm salmon full of antibiotics). How about roasted pig and roasted lamb? In all Mediterranean countries I have visited, that’s the food I have seen people enjoy.
People have lived since millennia enjoying all the goods our Earth has to offer in moderation. The size of our planet has not changed. The population of most nations has not changed or has decreased. Then why the need to change our habits? Because the population of certain regions is growing out of control? That’s their problem to solve.
The "Mediterranean diet" is its own thing and doesn't match the diet of actual Mediterranean countries in this century, and arguably wasn't even particularly close to the original 1960s populations that were studied. Other diets based on it, like ModiMed, move even further away from the original.
I agree that the name is silly and misleading, but that doesn't invalidate studies about its health benefits.
mb meat intake is positively correlated with having enough calories.
I.e. for people who are struggling to get enough to eat, of course they should eat meat. In contrast, I guess most readers of HN get enough calories and there will be no problem with eating veg
There are far cheaper sources of calories than meat. If anything, it's that meat is positively correlated with having enough nutrition, which is mostly the non calorie stuff. Lean meat is extremely nutritious, and relatively low calorie (since protein is incorrectly summed in caloric counts for meat, from 120 year old incorrect math [1], and the fact that the average person is never in a deep enough state of fasting/starvation for glycogenolysis to take over [2]).
Pasta, potatoes, grains, and sugar all provide more calories than meat for cheap. Especially that if you're a meat eater you're more likely to eat lean, unprocessed meat if you can afford that.
Meat is the most inefficient way to grow calories. Beef, for example:
> The inefficiency is particularly high for beef, which uses about three-fifths of the world’s agricultural land yet produces less than 5 percent of its protein and less than 2 percent of its calories.
Then it follows that meat intake is positively correlated with living somewhere that communities having enough surplus food or agricultural capacity to also feed/raise livestock.
In other words, they did not control for wealth or income, which quite obviously confound this entire exercise. Probably this paper is actively worse than useless.