How do you suppose that ‘eat like a sane person’ (as though that were precise advice) gives exactly optimal nutrition, with no gains to be had from any increase or decrease of anything? It seems vanishingly improbable that there is no substance that a human could benefit from getting slightly more or less of in the diet.
It does not seem vanishingly improbable to me. Any organism that must eat complex foodstuffs (which includes all animals big enough to see) must deal with the fact that they have no way to obtain precisely the right quantity and proportions of everything that they need. Their bodies therefore need to be robust to wide variations in their dietary content, resulting in a plateau, possibly a very wide one, between deficits and excesses that do measurable harm. If this is so, then there is no such thing as the exactly optimal amount of a nutrient. Instead, there is a broad range, and if you manage to hit that barn door it doesn’t matter where.
I think that what you say has to be true at the population level. (The panda provides an obvious counter example, but since the panda is going extinct, that is merely a nit pick. Successful species, such as rats or humans are robust to wide variations in their dietary content.
However, at the micro-level, the truth of this proposition is maintained by ruthless culling. The rat population is riddled with weaklings, who lose out in life due to diet-induced health problems.
As for the human population, we have a different perspective on these matters. I can start from a prior belief that my body is probably robust to wide variations in dietary content, but I need non-zero probabilities on a wide variety of dietary vulnerabilities so that updating will work if events supply evidence.
What we needed in the ancestral environment is exactly the same as what we need now
Already, there are a lot of substances I ingest that cause varying effects—increased productivity, increased creativity, increased fun, decreased pain—that each has its own tradeoffs. Even if it exists, I think the ‘plateau’ doesn’t account for everything I care about, and there is obvious room for improvement.
And it would be really weird if the plateau didn’t have some little peaks and valleys on it.
Moreover, the organism can afford to require precise balance between nutrients foobar and bazqux if they are nearly always found in the same proportions in its food. When you start supplementing foobar but not bazqux, you won’t like the results. And you’ll need a lot of knowledge to take into account all such interactions.
I am not a nutritionist, but I once read in The Economist that something like that was going on between omega-6 and omega-3, and between short- and long-chain omega-3.
It does not seem vanishingly improbable to me. Any organism that must eat complex foodstuffs (which includes all animals big enough to see) must deal with the fact that they have no way to obtain precisely the right quantity and proportions of everything that they need. Their bodies therefore need to be robust to wide variations in their dietary content, resulting in a plateau, possibly a very wide one, between deficits and excesses that do measurable harm. If this is so, then there is no such thing as the exactly optimal amount of a nutrient. Instead, there is a broad range, and if you manage to hit that barn door it doesn’t matter where.
I think that what you say has to be true at the population level. (The panda provides an obvious counter example, but since the panda is going extinct, that is merely a nit pick. Successful species, such as rats or humans are robust to wide variations in their dietary content.
However, at the micro-level, the truth of this proposition is maintained by ruthless culling. The rat population is riddled with weaklings, who lose out in life due to diet-induced health problems.
As for the human population, we have a different perspective on these matters. I can start from a prior belief that my body is probably robust to wide variations in dietary content, but I need non-zero probabilities on a wide variety of dietary vulnerabilities so that updating will work if events supply evidence.
That explanation seems to require:
“everything that we need” is optimal
What we needed in the ancestral environment is exactly the same as what we need now
Already, there are a lot of substances I ingest that cause varying effects—increased productivity, increased creativity, increased fun, decreased pain—that each has its own tradeoffs. Even if it exists, I think the ‘plateau’ doesn’t account for everything I care about, and there is obvious room for improvement.
And it would be really weird if the plateau didn’t have some little peaks and valleys on it.
Moreover, the organism can afford to require precise balance between nutrients foobar and bazqux if they are nearly always found in the same proportions in its food. When you start supplementing foobar but not bazqux, you won’t like the results. And you’ll need a lot of knowledge to take into account all such interactions.
Right, that’s what’s being called for. A lot of knowledge.
That sounds plausible. Any specific real-world examples?
I am not a nutritionist, but I once read in The Economist that something like that was going on between omega-6 and omega-3, and between short- and long-chain omega-3.