Moving on from observational studies and to randomized controlled trials, it’s unclear whether protein even has a meaningful effect on muscle strength, let alone something like lifespan, with some studies finding little or no effect from supplementation. It’s really not clear protein would help with sarcopenia from the studies, but we’d honestly expect null results from theory alone. We know from surveys that the limiting factor in most people’s muscle strength is physical activity, not protein. Most people get more than enough protein, and excess protein consumption turns into fat, not muscle. For most people, protein supplementation just can’t help because they aren’t moving enough.
The primary dietary determinants of health seem instead are mostly:
Polyunsaturated fatty acids (found in fish and vegetable oils)
Fiber (typically supplemented with psyllium husk)
I’m busy, so I’ll stick to looking at the evidence base we’ve acquired just on fiber supplementation. Here’s a bunch of insanely overpowered observational studies with sample sizes stretching into the hundreds of thousands, all showing reductions in all-cause mortality. Meta-analyses of RCTs? We’ve got those in spades.
There is a reason every doctor’s dietary advice is exactly the same: “Replace refined with whole grains, avoid saturated fats and replace them with unsaturated fats.” The reason is because we have million-person studies showing these interventions reduce heart disease. Note that heart disease is by far the leading cause of death among the elderly; sarcopenia doesn’t really kill, although it does make life substantially worse. And importantly, both of these are substantially more common in plants than in animal foods, which offers a pretty good explanation for why vegetarians seem to live longer, even after controlling for confounders. And also for why vegetarian diets seem to improve health markers in RCTs.
If you’re wondering whether the above studies leave some room for including fish in your diet: My guess is yes, pescetarianism is likely to be slightly healthier, because of the aforementioned effects of polyunsaturated fats (including omega-3 fatty acids). This is why doctors also recommend the Mediterranean diet a lot, although it’s not clear how much of the effect comes from fish and how much from vegetables. Omega-3 supplements definitely help.
With regards to protein: studies consistently show getting enough protein to prevent sarcopenia or other diseases is not especially difficult, and in fact most people get substantially more than the recommended daily allowances. Also important is that consuming animal protein is positively correlated with all-cause mortality, while plant protein is negatively correlated. From what I can tell, though, this is probably because fiber is confounding the results.
Moving on from observational studies and to randomized controlled trials, it’s unclear whether protein even has a meaningful effect on muscle strength, let alone something like lifespan, with some studies finding little or no effect from supplementation. It’s really not clear protein would help with sarcopenia from the studies, but we’d honestly expect null results from theory alone. We know from surveys that the limiting factor in most people’s muscle strength is physical activity, not protein. Most people get more than enough protein, and excess protein consumption turns into fat, not muscle. For most people, protein supplementation just can’t help because they aren’t moving enough.
The primary dietary determinants of health seem instead are mostly:
Polyunsaturated fatty acids (found in fish and vegetable oils)
Fiber (typically supplemented with psyllium husk)
I’m busy, so I’ll stick to looking at the evidence base we’ve acquired just on fiber supplementation. Here’s a bunch of insanely overpowered observational studies with sample sizes stretching into the hundreds of thousands, all showing reductions in all-cause mortality. Meta-analyses of RCTs? We’ve got those in spades.
There is a reason every doctor’s dietary advice is exactly the same: “Replace refined with whole grains, avoid saturated fats and replace them with unsaturated fats.” The reason is because we have million-person studies showing these interventions reduce heart disease. Note that heart disease is by far the leading cause of death among the elderly; sarcopenia doesn’t really kill, although it does make life substantially worse. And importantly, both of these are substantially more common in plants than in animal foods, which offers a pretty good explanation for why vegetarians seem to live longer, even after controlling for confounders. And also for why vegetarian diets seem to improve health markers in RCTs.
If you’re wondering whether the above studies leave some room for including fish in your diet: My guess is yes, pescetarianism is likely to be slightly healthier, because of the aforementioned effects of polyunsaturated fats (including omega-3 fatty acids). This is why doctors also recommend the Mediterranean diet a lot, although it’s not clear how much of the effect comes from fish and how much from vegetables. Omega-3 supplements definitely help.