One of the things that makes mainstream nutrition hard for me to buy is the evolutionary argument.
How can saturated fats, the main ingredients in breast milk and animal products, be bad for humans (an apex predator)? Was eating animals really giving our hunter gatherer ancestors heart attacks left and right?
Similarly for seed oils, through them we’re eating such a ridiculous amounts of PUFA; something that would be quite impossible in the ancestral environment. How can our bodies possibly be adapted to cope with that?
The consequence of this is that none of the studies we have, have any controls. If everyone is soaked in a food environment that drenches them in seed oils, how can a (even an RCT) study that gives people an extra tea spoon worth of seed oils a day really show anything? It’s like doing a study on a population of 20-cigarattes-a-day smokers, and seeing if randomizing one group to smoke one extra cigaratte amounts to anything.
These issues combined gives me such a strong prior on thinking saturated fats can’t possible be bad for you, that none of this evidence comes anywhere close to being convincing.
By what mechanism could natural selection have optimised our diets? Why should we expect long-tenured features of our diet to be necessarily healthy? We have consumed alcohol since long before we were modern humans, as one obvious counter-example to this sort of argument.
Saturated fats are definitely manageable in small amounts. For most of history, and still in many places today, the biggest concern for an infant was getting sufficient calories, and saturated fat is a great choice for that. When you look at modern hunter-gatherer diets, they contain animal products, but in most cases they do not make up the majority of calories (exceptions usually involve lots of seafood), the meats are wild and therefore fairly lean, and BMI stays generally quite low. Under those conditions, heart disease risk is small and whether it is slightly increased by the saturated fat in one’s diet is mostly irrelevant. There is a big difference between chasing down the occasional antelope and pulling up to the drive through for a cheeseburger. So the evolutionary argument really is not strong evidence that saturated fats are harmless.
I agree that the studies we have are mostly inadequate, but I don’t think using hunter-gatherer diets as a control would be very useful either. If you change everything at once, you can’t isolate specific causal factors. What we really need (but can’t have) is a bunch of large scale trials that have many groups with many different interventions and combinations of interventions, and statistical power to distinguish outcomes between each group.
How can saturated fats, the main ingredients in breast milk and animal products, be bad for humans (an apex predator)? Was eating animals really giving our hunter gatherer ancestors heart attacks left and right?
I think there’s a few issues with this reasoning.
For one thing, evolution wasn’t really optimizing for the health of people around the age where people usually start having heart attacks. There wasn’t a lot of selection pressure to make tradeoffs ensuring the health of people 20+ years after sexual maturity.
Another point is that animal sources of food represented a relatively small percentage of what we ate throughout our evolutionary history. We mostly ate plants, things like fruits and tubers. Of the groups who’s diets consisted of mostly meat, there is evidence of health issues resulting.
The nutritional profile of breast milk is intended for a human who is growing extremely quickly, not for long term consumption by an adult. Very different nutritional needs.
Similarly for seed oils, through them we’re eating such a ridiculous amounts of PUFA; something that would be quite impossible in the ancestral environment. How can our bodies possibly be adapted to cope with that?
I believe mainstream nutrition advises against consuming refined oils, including seed oils . I may be missing a point you’re making.
AFAIK, analysis of paleolithic diets is that there were a range of things depending on availability and some groups were indeed pretty high on animal protein. We don’t have differential analysis of the resulting health, but I just wanted to point out that the trope of ‘trad diets were low protein’ is not super well supported. Trad diets were mostly lower fat does have some support, as raising very fatty, sedentary animals is more recent, and accelerated a bunch in the last hundred years. Although the connection between higher fat diets and negative health outcomes is then another inferential step that hasn’t been strongly supported and is, AFAIK, somewhat genetically mediated (some people/groups do much better on high fat diets than others in terms of blood lipid profiles).
I don’t know enough to dispute the ratios of animal products eaten by people in the paleolithic era, but it’s still certainly true that throughout our evolutionary history plants made up the vast majority of our diets. The introduction of animal products representing a significant part of our diet is relatively recent thing.
The fact that fairly recently in our evolutionary history humans adapted to be able to exploit the energy and nutrition content of animal products well enough to get past reproductive age, is by no means overwhelming evidence that saturated fats “can’t possibly be bad for you”.
Although the connection between higher fat diets and negative health outcomes is then another inferential step that hasn’t been strongly supported
How would you define strongly supported?
We don’t have differential analysis of the resulting health
There is archeological evidence of Arctic people’s subsisting on meat showing atherosclerosis.
If some some pre-modern hominids ate high animal diets, and some populations of humans did, and that continued through history, I wouldn’t call that relatively recent. I’m not the same person making the claim that there is overwhelming evidence that saturated fats can’t possibly be bad for you. I’m making a much more restricted claim.
I am perhaps not speaking as precisely as I should be. I appreciate your comments.
I believe it’s correct to say that if you consider all of the food/energy we consumed in the past 50+ million years, it’s virtually all plants.
The past 2-2.5 million years had us introducing more animal products to greater or lesser extents. Some were able to subsist on mostly animal products. Some consumed them very rarely.
In that sense it is a relatively recent introduction. My main point is that given our evolutionary history, the idea that plants would be healthier for us than animal products when we have both in abundance, and the idea that plants are more suitable to maintaining health long past reproductive age, aren’t immediately/obviously unreasonable ideas.
One of the things that makes mainstream nutrition hard for me to buy is the evolutionary argument.
How can saturated fats, the main ingredients in breast milk and animal products, be bad for humans (an apex predator)? Was eating animals really giving our hunter gatherer ancestors heart attacks left and right?
Similarly for seed oils, through them we’re eating such a ridiculous amounts of PUFA; something that would be quite impossible in the ancestral environment. How can our bodies possibly be adapted to cope with that?
The consequence of this is that none of the studies we have, have any controls. If everyone is soaked in a food environment that drenches them in seed oils, how can a (even an RCT) study that gives people an extra tea spoon worth of seed oils a day really show anything? It’s like doing a study on a population of 20-cigarattes-a-day smokers, and seeing if randomizing one group to smoke one extra cigaratte amounts to anything.
These issues combined gives me such a strong prior on thinking saturated fats can’t possible be bad for you, that none of this evidence comes anywhere close to being convincing.
By what mechanism could natural selection have optimised our diets? Why should we expect long-tenured features of our diet to be necessarily healthy? We have consumed alcohol since long before we were modern humans, as one obvious counter-example to this sort of argument.
Saturated fats are definitely manageable in small amounts. For most of history, and still in many places today, the biggest concern for an infant was getting sufficient calories, and saturated fat is a great choice for that. When you look at modern hunter-gatherer diets, they contain animal products, but in most cases they do not make up the majority of calories (exceptions usually involve lots of seafood), the meats are wild and therefore fairly lean, and BMI stays generally quite low. Under those conditions, heart disease risk is small and whether it is slightly increased by the saturated fat in one’s diet is mostly irrelevant. There is a big difference between chasing down the occasional antelope and pulling up to the drive through for a cheeseburger. So the evolutionary argument really is not strong evidence that saturated fats are harmless.
I agree that the studies we have are mostly inadequate, but I don’t think using hunter-gatherer diets as a control would be very useful either. If you change everything at once, you can’t isolate specific causal factors. What we really need (but can’t have) is a bunch of large scale trials that have many groups with many different interventions and combinations of interventions, and statistical power to distinguish outcomes between each group.
I think there’s a few issues with this reasoning.
For one thing, evolution wasn’t really optimizing for the health of people around the age where people usually start having heart attacks. There wasn’t a lot of selection pressure to make tradeoffs ensuring the health of people 20+ years after sexual maturity.
Another point is that animal sources of food represented a relatively small percentage of what we ate throughout our evolutionary history. We mostly ate plants, things like fruits and tubers. Of the groups who’s diets consisted of mostly meat, there is evidence of health issues resulting.
The nutritional profile of breast milk is intended for a human who is growing extremely quickly, not for long term consumption by an adult. Very different nutritional needs.
I believe mainstream nutrition advises against consuming refined oils, including seed oils . I may be missing a point you’re making.
AFAIK, analysis of paleolithic diets is that there were a range of things depending on availability and some groups were indeed pretty high on animal protein. We don’t have differential analysis of the resulting health, but I just wanted to point out that the trope of ‘trad diets were low protein’ is not super well supported. Trad diets were mostly lower fat does have some support, as raising very fatty, sedentary animals is more recent, and accelerated a bunch in the last hundred years. Although the connection between higher fat diets and negative health outcomes is then another inferential step that hasn’t been strongly supported and is, AFAIK, somewhat genetically mediated (some people/groups do much better on high fat diets than others in terms of blood lipid profiles).
I don’t know enough to dispute the ratios of animal products eaten by people in the paleolithic era, but it’s still certainly true that throughout our evolutionary history plants made up the vast majority of our diets. The introduction of animal products representing a significant part of our diet is relatively recent thing.
The fact that fairly recently in our evolutionary history humans adapted to be able to exploit the energy and nutrition content of animal products well enough to get past reproductive age, is by no means overwhelming evidence that saturated fats “can’t possibly be bad for you”.
How would you define strongly supported?
There is archeological evidence of Arctic people’s subsisting on meat showing atherosclerosis.
If some some pre-modern hominids ate high animal diets, and some populations of humans did, and that continued through history, I wouldn’t call that relatively recent. I’m not the same person making the claim that there is overwhelming evidence that saturated fats can’t possibly be bad for you. I’m making a much more restricted claim.
I am perhaps not speaking as precisely as I should be. I appreciate your comments.
I believe it’s correct to say that if you consider all of the food/energy we consumed in the past 50+ million years, it’s virtually all plants.
The past 2-2.5 million years had us introducing more animal products to greater or lesser extents. Some were able to subsist on mostly animal products. Some consumed them very rarely.
In that sense it is a relatively recent introduction. My main point is that given our evolutionary history, the idea that plants would be healthier for us than animal products when we have both in abundance, and the idea that plants are more suitable to maintaining health long past reproductive age, aren’t immediately/obviously unreasonable ideas.