Breast milk tells us everything about the
optimal infant diet, much about the
optimal diet of children, and is
supporting evidence for our view of the
adult diet.
Regarding carbohydrates, it tells us
that carbs should account for 39 percent
of calories in infants and then a
gradually decreasing fraction of energy
as children grow into adults.
It doesn’t
tell us the optimal carb fraction for
adults—we’ll need more evidence—but
we can be pretty sure that the “cannibal
diet” of fasting is too low in carbs, and
the Paleolithic diet might have been too
low in carbs.
So optimal adult carb
intake is probably above 20 percent but
probably not more than 35 percent of
total energy intake.
Breast milk probably gives us an
upper limit to the optimal adult PUFA
intake. Infants obtain about 9.6 percent
of their energy as PUFA, but they have a
great need for PUFA to support the rapid
growth of the infant brain. Adults, who
have a stable brain size, need
substantially less dietary PUFA.
Breast milk confirms that saturated
and monounsaturated fats should be the
largest source of calories at all ages.
There’s no good reason to be afraid of
fats!
