"The Great Protein Fiasco"
There has been a history of enthusiasm
for protein in the nutrition world.
A century ago the protein requirements
were more than twice what we know them to be today.
This enthusiasm peaked in the 1950’s
with the United Nations identifying protein deficiency
as a serious widespread global problem.
There was a protein gap that needed to be filled.
This was certainly convenient for the U.S. dairy industry,
who could dump their postwar surplus
of dried milk onto the third world
rather than having to just bury it.
But this led to the great protein fiasco.
There was a disease of malnutrition called kwashiorkor
that was assumed to be caused by protein deficiency,
famously discovered by Dr. Cicely Williams,
who spent the latter half of her life debunking
the very condition that she first described.
Turns out there’s no real evidence of dietary protein deficiency.
The actual cause of kwashiokor remains obscure,
but fecal transplant studies suggest changes in gut flora
may be a causal factor.
How could the field of nutrition
have gotten it so spectacularly wrong?
A famous editorial about the profession
started with these words.
“The dispassionate objectivity of scientists is a myth.
No scientist is simply involved
in the single-minded pursuit of truth.
He or she is also engaged in the passionate pursuit
of research grants and professional success.
Nutritionists may wish to attack malnutrition,
but they also wish to earn their living
in ways they find congenial.”
This inevitably encourages researchers
to "make a case" for the importance
of their own portion of the field and "their nutrient,"
which was protein.
Science eventually prevailed, though,
and there was a massive recalculation
of human protein requirements in the 1970’s,
which ‘at the stroke of a pen’
closed the so called ‘protein gap’
and destroyed the theory of this pandemic
of ‘protein malnutrition’.
Infant protein requirements
went from a recommended 13% of daily calories,
down to 10%, then 7, then down to 5%.
However to this day there are still
those obsessing about protein.
Those promoting Paleolithic diets, for example,
try to make the case for protein
from an evolutionary perspective.
OK, so let's ask the question:
what is the perfect food for human beings?
The food that was fine-tuned just for us
over millions of years
to have the perfect amount of protein?
Human breast milk.
If high-quality protein was the “nutrient among nutrients”,
helping us build our big brains
over the last few million years,
one would expect that importance
to be resoundingly reflected
in the composition of human breast milk,
especially since infancy is the time
of our most rapid growth.
But this is patently not the case.
Human breast milk is one of the lowest-protein milks
in the mammalian world.
In fact, it may have the lowest protein concentration
of any animal in the world—
less than 1% protein by weight.
This is one of the reasons why feeding straight cow’s milk
to babies can be so dangerous.
The protein content in human milk
is described as extremely low,
but it’s not low at all.
It's right where it needs to be.
That’s the natural, normal level
for the human species fine-tuned over millions of years.
Adults require no more than 0.8 or 0.9 grams of protein
per healthy kilogram of body weight per day.
So that’s like your ideal weight in pounds
multiplied by four and then divided by ten.
So someone who’s ideal weight is 100 pounds
may require up to 40 grams of protein a day.
On average they probably only need about 30 grams a day,
which is 0.66 grams per kilogram,
but we say 0.8 or 0.9 because everyone’s different
and we want to capture most of the bell curve.
People are more likely to suffer
from protein EXCESS than protein deficiency.
The adverse effects associated with long-term
high protein diets may include
disorders of bone and calcium balance,
disorders of kidney function, increased cancer risk,
disorders of the liver,
and worsening of coronary artery disease.
Therefore, there is currently no reasonable scientific basis
to recommend protein consumption
above the current recommended daily allowance
due to its potential disease risks.