In this case, individuals who eat more that 5 servings of fruits and vegetables probably also exhibit a whole host of behaviors that contribute to this outcome. Essentially, they are not a representative sample of the population at large, but rather a sub-group who is "healthful" in a whole bunch of ways.

Building a double-blind clinical trial regarding changing people's diets over their lifetime and observing cardiovascular mortality is very hard.

Some clinical studies do exist, but they are usually looking over shorter terms and at heart disease risk factors rather than mortality. These show similar results:

https://www.ncbi.nlm.nih.gov/pubmed/16368299 - Systolic blood pressure decreased from 144 (SE +/- 1.1) to 134 mm Hg (SE +/- 2, P < .001), and diastolic blood pressure decreased from 87.4 (SE +/- 1.2) to 83.4 mm Hg (SE +/- 1.2, P < .05) from tomato extract.

https://www.ncbi.nlm.nih.gov/pubmed/26328470 - In the subgroup of hypertensives, quercetin (onion skin extract) decreased 24 h systolic BP by -3·6 mmHg (P=0·022) when compared with placebo (mean treatment difference, -3·9 mmHg; P=0·049).

Many of the epidemiological studies also adjust for many of the features that you might look for. For example https://academic.oup.com/ije/article/30/1/130/619054 adjusts for "age, randomized treatment, body mass index (BMI), smoking, alcohol intake, physical activity, history of diabetes, history of hypertension, history of high cholesterol, and use of multivitamins" and comes to the same conclusion.

But it is the only diet research that can actually generate knowledge.

The studies you cite are nice and all, but the first two are for studies that measured outcomes after 6-8 weeks. If you assume an average lifespan of 70 years, the longest study represented ~1/450th of a human lifespan. And, as you mention, they only measure what we think are valid indicators, not actual outcomes! And the third study may control for all of the things you mention, but it doesn't control for the other foods the study participants ate!

Really the only piece of information that you need to know regarding red meat is that public health messaging for the last 50 years has been that people should limit red meat intake. And it was successful. According to this[0], red meat consumption has decreased from 133lbs per person in 1965 to 107lbs per person in 2016. But it is during this exact same time period that the obesity epidemic came into existence. So, perhaps red meat is marginally bad for you, but it is almost certainly not cause of all of the various afflictions that we think are caused in some way by our diets.

[0]: https://www.nationalchickencouncil.org/about-the-industry/st...

> The studies you cite are nice and all, but the first two are for studies that measured outcomes after 6-8 weeks. If you assume an average lifespan of 70 years, the longest study represented ~1/450th of a human lifespan. And, as you mention, they only measure what we think are valid indicators, not actual outcomes! And the third study may control for all of the things you mention, but it doesn't control for the other foods the study participants ate!

I fully agree with everything you wrote about the science here.

However, many of the epidemiological studies are over very large populations and time periods, so it's not as though the body of evidence consists of a 6-8 week studies. And honestly the fact that the effects are so strong in such a short period of time strengthen the argument in some ways.

> Really the only piece of information that you need to know regarding red meat is that public health messaging for the last 50 years has been that people should limit red meat intake. And it was successful. According to this, red meat consumption has decreased from 133lbs per person in 1965 to 107lbs per person in 2016. But it is during this exact same time period that the obesity epidemic came into existence. So, perhaps red meat is marginally bad for you, but it is almost certainly not cause of all of the various afflictions that we think are caused in some way by our diets.

Interesting response. I never claimed that meat was bad, only that leafy vegetables were good. I find it almost incredible that your argument against the nutritional value of leafy vegetables is that there aren't enough double blind clinical trials, and then your defense of red meat uses a time correlation that doesn't adjust for any confounding variables at all. It also cites a document from an meat industry group. If you look at USDA numbers (https://www.ers.usda.gov/data-products/food-availability-per...), overall meat consumption has been consistently and slowly rising, however beef is being replaced with chicken, so yes red meat consumption is declining.

The studies all tell us nothing about the long term implications of diet. The long study tells us nothing because it is purely correlational. The short studies tell us nothing because they are not measuring the thing we care about (long term health outcomes). You can't somehow generate knowledge by combining two types of studies which each are incapable of generating knowledge about the thing we care about.

> I never claimed that meat was bad, only that leafy vegetables were good.

Yeah, I clearly was hallucinating. Nowhere did you mention red meat. And yet I rambled on about it for a paragraph. :-) Sorry!

But:

> I find it almost incredible that your argument against the nutritional value of leafy vegetables is that there aren't enough double blind clinical trials, and then your defense of red meat uses a time correlation that doesn't adjust for any confounding variables at all.

That's because correlation cannot demonstrate causation, but it can demonstrate the lack of causation. It's all about confounding variables, as you point out. If you have two trend lines which correlate, there can always be a third, unmeasured variable which is actually causing the two measured variables. However, if you have trend lines which do not correlate, then the only way they can be related is by some extremely convoluted chain of causation. Which, I guess, is technically possible, but rapidly approaches 0 probability.

In other words, epidemiology is very useful for narrowing the possibly explanations for some phenomena, and it can suggest places where we should continue focusing our attention, but it can't actually tell us if we've found the right culprit.

Any nonlinear enough process will show with wrong low correlations.

Suppose the process is stepwise - silly sample hypothesis, eating over x grams meat a day is harmful. It is binary. Correlation is meaningless for such a process. You have to use significantly more powerful statistic tools. Logistic regression will somewhat work for such a process for instance if the boundary is somewhat fuzzy. (You can put exact mathematical bound on how fuzzy.)

To extend it for multivariate analysis you get to use such complex tools as nonlinear ICA. (Instead of CCA and PCA for linear.)

Now, it may be that there is a different relationship, like the one that you mention: that eating more than X grams per day is harmful. The data from an observational study can negate this hypothesis (if there is no threshold pattern evident in the data), but it cannot prove the hypothesis. All it can do, at best, is let you know that the hypothesis might be true.

This is very rare and hard to run, so more direct interventional short term studies are used more often.

Suppose a certain country believed an observational study pointing that eating more than certain amount of sugar is harmful (suppose backed by other evidence). They instated hard tax and limit on sugar in foods as an intervention. After some time a big observational study is ran and it is assessed if the intervention brought results.

This is precisely what observational studies (follow up) should do. Not really try to find hypotheses - these need more direct evidence.

Red meat consumption is on the rise: https://www.bloomberg.com/news/articles/2018-01-02/have-a-me...

https://www.ers.usda.gov/data-products/livestock-meat-domest...

Scroll down to the Beef pivot table. Increases year over year.

Yes, red meat consumption is on the rise, along with others.

And, given that this same time frame has coincided with the obesity epidemic, it seems hard to make the case that red meat is bad for you. I think the best argument you could make is that red meat is bad for you in a small way, but something else is causing the Really Bad Stuff™. I'm open to changing my mind, but the data has to lead me there.

[0]: https://www.ers.usda.gov/amber-waves/2017/januaryfebruary/us...

Even Karl Popper believed in astronomy.

I guess the difference between astronomy and diet is that, in my conception, at least, the systems studied in astronomy tend to be less complex than the human body and, therefore, they can be modeled relatively easily. My hunch is that this has something to do the human body being a self regulating, though climate systems on earth are probably of a similar level of complexity, yet are not self regulating (or at least, not in the same way).

So, the difference in complexity between a astronomical system and the human body would be akin to the difference in complexity between a program which implements some relatively straightforward business logic vs. one that implements a system which can identify and hunt prey. You can probably prove the correctness of most programs which implement basic business logic, but I'm guessing a system which can identify and hunt prey probably cannot be proven to be formally correct. You would need to test it in the real world by tweaking inputs and measuring how it responds.

To needle you slightly further, though, I'd recommend you consider John Snow's investigation into cholera clusters near certain water sources in London: https://en.wikipedia.org/wiki/1854_Broad_Street_cholera_outb...

What should we make of that?

Ok, more generally...

I'm glad you're giving this some thought, because this line of inquiry (or something like it) really affected the way I think about science and knowledge. It's an incredibly rewarding line to go down, though not entirely free of frustrating dead ends.

If you find this stuff interesting, you might want to poke around a bit in 20th century philosophy. There are some (needlessly lengthy) summaries at the Stanford Encyclopedia of Philosophy, esp. under "Logical Empiricism." I hesitate to recommend that, though, it's long on history and short on significant arguments and though-provoking examples.

"Two Dogmas of Empiricism" by Quine profoundly affected the way I think about all of this. It's not an easy piece, I had to read it a few times and kept turning it over in my head for months. At first I thought it was nonsense. Then I thought it was just wrong. Then it sort of wormed its way into my head and changed a few core things I believed about knowledge. Or reorganized them. Karl Popper, Rudolf Carnap, and Wittgenstein all had profound contributions here too.

At the end of Quine's paper he says that White basically said everything important on this already in "The Analytic and the Synthetic: An Untenable Dualism." I haven't read that, but maybe it's the accessible version. One could hope.

http://www.thatmarcusfamily.org/philosophy/Course_Websites/R...

Obviously it's an imperfect experiment, but it seems like a pragmatic compromise.

https://jamanetwork.com/journals/jamainternalmedicine/fullar...

There are many other short term studies that support this fully. You may not want to believe red meat consumption is indicative of negative health indicators, but most notable cardiologists in the field fully support the position.

Edit: vegetable --> plant, and if I win (we can agree on some defined objective comparisons and scoring offline) I'll even donate the money you'd have repaid back to the charity of my choosing. I'd be glad to make our miminal findings public as well.

Read Good Calories, Bad Calories by Gary Taubes if you want to do a deep dive on how so many people can be so wrong about something for so long. It will completely undermine your faith in experts along the way.

[0]: https://www.nytimes.com/2007/09/16/magazine/16epidemiology-t...

[1]: https://www.ers.usda.gov/amber-waves/2017/januaryfebruary/us...

In fact, the study he proposed to test his hypothesis failed: https://community.fitbit.com/t5/Manage-Weight/NuSI-study-bac...

That's not to say Taubes has not written a lot of good and important things, but it is an example of someone who is in so deep that they are missing the forest for the trees. Carbs are obviously not the devil, it's just that the overabundance of cheap, processed carbs have made the diseases of abundance commonplace.

You should read it. Seriously. It’s way more important than anything else on HN right now. I promise.

My guess here is that it's because you offered somebody a 6-12 month physical challenge on a discussion thread about nutrition. Unless you're willing to engage in a 6-12 month comprehensive study of messageboard thread challenges, which we will cofinance (but in the end, if we find that these types of challenges are generally accepted as arguments, I'll compensate you for your half of the research budget, and vice-versa), you must concede that that's a silly thing to wonder about...

Do you have a link to your before/after panels? I'd be curious to see this, and also be interested in your before/after diet.

Your general point is reasonable enough, but this arithmetic per se is not really supportable. (a) There is no breakdown there of the number of people who ate > 5 vs. < 3 servings of vegetables (either among the general population or among heart disease sufferers), and (b) the risk number is about developing heart disease at all, not deaths (without even mentioning (c) these are cohort studies showing correlations, not proving causal relationships).

It is possible that e.g. serious heart-disease cases likely to cause death result from causes unrelated to vegetable consumption, while many non-vegetable-eaters develop minor heart disease cases which they would not have if they had eaten vegetables, but which still do not result in death.

Likewise, it is likely that of the 610,000 deaths, many (most?) of them were of people eating > 3 servings of vegetables per day.

You don’t avoid concern about increasing food borne pathogens in lettuce because of heart disease. The issue is the economic and regulatory environment that is making contaminated lettuce a thing.

If it’s like E. coli problems in meat, the primary contributor is poor production, handling and packaging process.

But there's a lot of ambient food poisoning that can be prevented by washing lettuce, especially in reducing cross-contamination (the lettuce wasn't contaminated, then got exposed during the cooking prep process, etc.)

It's unfortunate that some are advocating just abandoning chapters of our local cuisine as being no longer viable in our era. I'd rather we more strongly enforce regulations so we can hold onto our salads.

http://www.slate.com/articles/health_and_science/green_room/...

[1] http://www.lowtechmagazine.com/2010/09/recycling-animal-and-...

Some nutrients in some vegetables are diminished by cooking (https://onlinelibrary.wiley.com/doi/full/10.1111/j.1750-3841... for example). Some are also enhanced. For example: lycopene from tomatoes. Overall, it seemed to me that cooking often harms nutrition more than it helps.

I know evolutionary biology isn't as intuitive as people always assume, but theoretically this fits within my model - digestion burns precious calories (at least in a world with too many calories), breaking down the food using fire somewhat allows for the body to spend less calories on breaking it down itself. So our ancestors who used fire to cook had an advantage because they could spend less calories on digestion.

Archaeological evidence suggests that humans can control fire between 700,000 years ago and 120,000 years ago.

There's also a hypothesis that the nutritional changes allowed through cooking increased our brain size - https://en.wikipedia.org/wiki/Control_of_fire_by_early_human....

But fundamentally, I wonder if we cook too much. Some compounds are very fragile, and cooking would harm nutrition (as you said). As I said, not my field, but I try to stick to a lot of leafy greens as is recommended by health services, and the occasional cooked proteins.

People want to eat more and get less calories, not the other way around.

FTFY.. it's a bad idea to make absolute statements like that

It's not clear that this is relevant to heart disease. Vitamin C, for example, is degraded by heat, but has no role in preventing heart disease. "Antioxidants" is the smoke signal of the woo practitioner.

>Overall, it seemed to me that cooking often harms nutrition more than it helps.

This is such a common and annoying myth that I need to call it out as such. Humans literally evolved to eat cooked food.

http://img2.timg.co.il/forums/1_142929513.pdf

http://symposium.cshlp.org/content/early/2009/10/19/sqb.2009...

https://www.karger.com/Article/Abstract/16498

https://www.karger.com/Article/Abstract/12770

https://jamanetwork.com/journals/jamainternalmedicine/fullar...

Also, lycopene is not a "nutrient".

And there's a whole thing to say about frigerator hygiene - they are not sterile just because of lower temperatures, while they are hard to clean unless turned off, because water won't dry, whereas they are hard to turn off, when they are always filled. I'm being pedantic, I know.