"Animal Protein vs. Plant-Based Protein"
In 2019, Dr. David Katz and colleagues—
including one of my favorite researchers, David Jenkins—
published a public health case for modernizing
the definition of protein quality.
The prevailing definition seems to have more to do with biochemistry
than the net effects on human health.
The popular concept that protein is good, and the more the better,
coupled with a protein quality definition that favors animal protein,
fosters the impression that eating more meat, eggs, and dairy
is desirable and preferable, but this is directly opposed
to nutrition guidelines that are instead trying to push more plants.
Although protein malnutrition is still prevalent in many areas of the world,
it is exceedingly rare in the industrialized world,
where the most formidable public health threat
is not something like kwashiorkor— protein/calorie malnutrition—
but from chronic diseases.
In 2016, a landmark study was published out of Harvard,
involving more than 100,000 people, that found that replacing animal protein
with plant protein was associated with lower risk of dying prematurely.
The worst seemed to be processed meat like bacon,
as well as egg protein, the egg whites,
but swapping in even just 3% plant protein for any of the animal proteins—
processed meat, unprocessed meat, chicken, fish, eggs, or dairy—
was associated with a significantly lower risk
of arguably the most important endpoint of all: death.
Yeah, but how do we know it's the protein?
The researchers adjusted for factors such as saturated fat intake,
which suggested it wasn't just the animal fat.
Okay, but how does your body even know the difference
between protein from a plant and protein from an animal?
Isn't protein, protein?
No. Unlike animal protein, plant protein is generally low
in branched-chain amino acids, for example,
and decreased consumption of branched-chain amino acids
improves metabolic health.
It could be the IGF-1,
a cancer-promoting growth hormone that is boosted
by so-called high-quality animal protein intake, though.
We suspect the IGF-1 connection is cause and effect,
since people who are born to have higher IGF-1 levels
regardless of what they eat do appear to suffer
higher rates of killers like type 2 diabetes and heart disease.
Or it could be something the Harvard researchers didn't control for
such as toxic pollutants like as dioxins and PBCs,
since they tend to accumulate up the food chain in cattle,
pigs, chickens, and fish, and therefore end up on our plates.
So plant-based protein also stands as an important step
to lower the body burden of harmful pollutants.
If you don't think 100,000 people are enough,
how about 400,000 people?
The NIH-AARP study is the largest diet cohort study in history.
And again, simply swapping 3% of calories from various
animal protein sources with plant protein
was associated with 10% decreased overall mortality,
and you get even twice that benefit if you get rid of eggs, too.
That's not a surprise, since egg consumption is associated
with a higher risk of developing cardiovascular disease.
Put all the studies together on dietary protein intake and mortality,
and people who eat more protein tend to live shorter lives,
but this is mainly driven by the harmful association of animal protein.
Plant protein intake is inversely associated with mortality,
meaning those who eat more plant protein tend to live longer lives.
More animal protein may mean more mortality,
whereas more plant protein is correlated with less mortality.
So the best of both worlds would be to increase
the intake of plant protein in place of animal protein.
In other words, as another 2020 meta-analysis concluded,
"Persons should be encouraged to increase their plant protein intake
to potentially decrease their risk of death."