The question science isn’t ready to answer

No, it doesn’t tell us nothing. These kinds of limitations are not uncommon for nutrition studies. It just is weaker evidence that doesn’t tell everything we ever might want. Studies will always have some methodological limitations. There is always some factor you might be forgetting or could do better. Science doesn’t work by looking at induvidial studies alone. We take things in aggregate

That being said, of course things like RCTs will always be preferred and considered much stronger evidence. On that front, there have been some RCTs in other related health risk incidents with similar findings. For instance, I have read about some RCT studies for cardiovascular health. One meat industry funded review of RCT studies on cardiovascular risk for red meat found plant substitution improved predictors of cardiovascular health

Substituting red meat with high-quality plant protein sources, but not with fish or low-quality carbohydrates, leads to more favorable changes in blood lipids and lipoproteins.

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.118.035225#d3646671e1

Or from another review looking at larger changes

Nevertheless, several RCTs have examined the effect of vegetarian diets on intermediate risk factors of cardiovascular diseases (Table 1). In a meta-analysis of RCTs, Wang et al. (22) found vegetarian diets to significantly lower blood concentrations of total, LDL, HDL, and non-HDL cholesterol relative to a range of omnivorous control diets. Other meta-analyses have found vegetarian diets to lower blood pressure, enhance weight loss, and improve glycemic control to greater extent than omnivorous comparison diets (23-25). Taken together, the beneficial effects of such diets on established proximal determinants of cardiovascular diseases found in RCTs, and their inverse associations with hard cardiovascular endpoints found in prospective cohort studies provide strong support for the adoption of healthful plant-based diets for cardiovascular disease prevention

https://www.sciencedirect.com/science/article/am/pii/S1050173818300240

Also for people who prefer roasted, but don’t want to go through the effort of waiting for an oven to preheat: using an air fryer has changed how I cook vegetables. It’s amazing how “what if we made a convention oven, but smaller” is actually really helpful because it heats up super fast. Very convenient to roast them with an air fryer and very tasty

Yes, this new study has limitations. The authors do note that and aren’t pretending otherwise. This is coming in the context of other studies with similar conclusions which the original article talks about. This new study is a singular imperfect data point, but is combined with other data points that point in the same direction.

What it is primarily helpful for is in that it has a large N value of 79,468 participants and the population they are looking at doesn’t partake in as many carcinogens that make it harder to tell cancer rates apart (which is both a strength and also a study limitation too)

From the study

This study has several other strengths. 1) This is probably the single cancer cohort with the largest number of vegetarians, and especially vegans, who have rarely been studied effectively for cancer incidence. This allows consistent definitions and methods to be applied across all variables; 2) in many studies of vegetarians, vegetarian diets may be relatively transient for some subjects, but less so in AHS-2; 3) the level of validation available for the main variables on which the assignment to vegetarian diets is based; 4) the relatively large Black subgroup in which vegetarian diets have rarely been studied. Race is always a co-variate in our statistical models; and 5) the absence (practically) of cigarette smoking, a common confounder for many cancers, and very little alcohol

There are also study limitations, the most prominent of which is still the relatively small numbers of less common cancers, particularly among the less common dietary patterns (vegans and pesco-vegetarians) that diminish statistical power; second, there is the relatively health-conscious low-meat-consuming reference group, the Adventist nonvegetarians, that also limits power; third, that we were able to measure dietary and other data only at study baseline and not during follow-up. Finally, there are the limitations of all observational studies, particularly the possibility of unmeasured confounding, which can be limited but never avoided

This is an article that talks about multiple studies with differing methodology, including one new one. Posting without reading the article does not help actually advance discussion in general. Posting without reading just reaffirm existing beliefs

For instance, the new study itself did not use the term “plant heavy”, they looked at different sub groups

Humans and human ancestors have also been consuming large quantities of plants for far earlier than that. Here’s another paper looking 780,000 years ago finding a wide amount of plants consumed

we demonstrate that a wide variety of plants were processed by Middle Pleistocene hominins at the site of Gesher Benot Ya’aqov in Israel (33° 00’ 30” N, 35° 37’ 30” E), at least 780,000 y ago. These results further indicate the advanced cognitive abilities of our early ancestors, including their ability to collect plants from varying distances and from a wide range of habitats and to mechanically process them using percussive tools.

https://www.pnas.org/doi/10.1073/pnas.2418661121

I am not saying that hunting didn’t happen (it definitely did). I am just saying that more recent research is painting a very different picture of the level of consumption of it

More modern research does not suggest this made up most of the consumption for humans even before agriculture. For instance,

Our results unequivocally demonstrate a substantial plant-based component in the diets of these hunter-gatherers. This distinct dietary pattern challenges the prevailing notion of high reliance on animal proteins among pre-agricultural human groups

https://www.nature.com/articles/s41559-024-02382-z

Does the Lemmy post title not have “in mice” in it for you? I added it to the title of the post to clarify this. It should show as

Red meat wreaks havoc on gut and drives inflammatory bowel disease (IBD) in study on mice

Whereas the original title of the article was:

Red meat wreaks havoc on gut and drives inflammatory bowel disease

My point is that it was way more rare than what people’s diets look like today. Not zero but not dominant. Wide reliance on plants is even true before modern agriculture. For example:

Here we present the isotopic evidence of pronounced plant reliance among Late Stone Age hunter-gatherers from North Africa (15,000–13,000 cal BP), predating the advent of agriculture by several millennia

https://www.nature.com/articles/s41559-024-02382-z

Humans historically, also didn’t eat much meat up until very recently. More recent research suggests our ancient human ancestors were eating far more plants than meat

EDIT: For example:

Here we present the isotopic evidence of pronounced plant reliance among Late Stone Age hunter-gatherers from North Africa (15,000–13,000 cal BP), predating the advent of agriculture by several millennia

https://www.nature.com/articles/s41559-024-02382-z

Not that useful in scenarios besides reading: if you curl your hands in front of your eye and leave a very tiny opening you can create a pinhole that’ll make a tiny bit of your view in focus

Photo from Minute Physics demonstrating what you need to do for that:

https://youtu.be/OydqR_7_DjI

Maybe worth reminding her of that option too. A lot of people do things for culture because they feel like they are required or supposed to, even if they might feel better not taking part in certain practices

If I were to hazard a guess, I’m going to imagine that this won’t completely solve the feeling bad/guilty about it aspects. Another option to consider: can always just have something else

It’s very much human to have those feelings and healthy in the short term to have those feelings, but we should generally try to listen to them or they eat away us. Or in the really cheesy way of putting it “listen to your heart”

Cheesemaking uses even more dairy than it being in liquid form. Varies depending on what you’re looking at but it can be around a 10:1 ratio. Butter from dairy milk has an even worse conversion

Have to make up for the lost water when turning it into a solid and other stuff you strip from the milk and that’s going to be from even more dairy going into it

This graph is normalized per kg. Graphs look similarly per kcal as well

It’s enough to make it difficult to keep to 2C climate targets on its own. Its not something we should ignore - especially since much of it comes in methane emissions which means reduction in it can be felt quicker and reduce chance of hitting feedback loops. We must tackle all sources

To have any hope of meeting the central goal of the Paris Agreement, which is to limit global warming to 2°C or less, our carbon emissions must be reduced considerably, including those coming from agriculture. Clark et al. show that even if fossil fuel emissions were eliminated immediately, emissions from the global food system alone would make it impossible to limit warming to 1.5°C and difficult even to realize the 2°C target. Thus, major changes in how food is produced are needed if we want to meet the goals of the Paris Agreement.

https://www.science.org/doi/10.1126/science.aba7357

That’s also on top of other environmental issues that it contributes to besides just climate change. Land usage, water usage, waste runoff

Transitioning to plant-based diets (PBDs) has the potential to reduce diet-related land use by 76%, diet-related greenhouse gas emissions by 49%, eutrophication by 49%, and green and blue water use by 21% and 14%, respectively, whilst garnering substantial health co-benefits

https://www.mdpi.com/2072-6643/14/8/1614/html

And pesticide and fertilizer usage is lower

Thus, shifting from animal to plant sources of protein can substantially reduce fertilizer requirements, even with maximal use of animal manure

https://www.sciencedirect.com/science/article/abs/pii/S0921344922006528

The diet containing more animal products required an additional 10 252 litres of water, 9910 kJ of energy, 186 g of fertilizer and 6 g of pesticides per week in comparison to the diet containing less animal products

https://www.cambridge.org/core/journals/public-health-nutrition/article/comparing-the-water-energy-pesticide-and-fertilizer-usage-for-the-production-of-foods-consumed-by-different-dietary-types-in-california/14283C0D55AB613D11E098A7D9B546EA

For agriculture at least, the differences are often quite categorical. The best cast production will not get you the same differences as reducing meat consumption

Plant-based foods have a significantly smaller footprint on the environment than animal-based foods. Even the least sustainable vegetables and cereals cause less environmental harm than the lowest impact meat and dairy products [9].

https://www.mdpi.com/2072-6643/14/8/1614/html

It’s an even larger difference than eliminating all food waste (which we should also work to reduce)

we show that plant-based replacements for each of the major animal categories in the United States (beef, pork, dairy, poultry, and eggs) can produce twofold to 20-fold more nutritionally similar food per unit cropland. Replacing all animal-based items with plant-based replacement diets can add enough food to feed 350 million additional people, more than the expected benefits of eliminating all supply chain food loss.

https://www.pnas.org/doi/abs/10.1073/pnas.1713820115

If we assume that’s the case, half of revenue is still not a byproduct, it’s a coproduct. The other half is still pretty relevant to its value and usage. If 50% of your revenue disappears from something, you’re going to be making a lot less of it

It’s worth noting that soybean meal is not a byproduct. When we look at the most common extraction method for soybean oil (using hexane solvents), soybean meal is still the driver of demand

However, soybean meal is the main driving force for soybean oil production due to its significant amount of productivity and revenues

[…]

soybean meal and hulls contribute to over 60% of total revenues, with meal taking the largest portion of over 59% of total revenue

https://www.sciencedirect.com/science/article/abs/pii/S0926669017305010

This is even more true of other methods like expelling which is still somewhat commonly used

Moreover, soybean meal is the driving force for the whole process [expelling oil from soy] because it provides over 70% of the total revenue for soy processing by expelling

https://www.mdpi.com/2077-0472/9/5/87

Good news is that overall arable farmland usage goes down the less meat you eat. Don’t need to use all the same land, you have flexibility to move around production

we show that plant-based replacements for each of the major animal categories in the United States (beef, pork, dairy, poultry, and eggs) can produce twofold to 20-fold more nutritionally similar food per unit cropland. Replacing all animal-based items with plant-based replacement diets can add enough food to feed 350 million additional people, more than the expected benefits of eliminating all supply chain food loss.

https://www.pnas.org/doi/abs/10.1073/pnas.1713820115