"Animal Protein, Pregnancy, and Childhood Obesity"
If you exposed pregnant crickets to a predatory wolf spider,
her babies will hatch,
exhibiting increased anti-predator behavior,
and as a consequence, improved survival
from wolf spider attack.
The mother cricket appeared to be able to forewarn her babies
about the threat when they were still inside her
so they would be pre-adapted to their external environment.
This even happens in plants.
If you grow two genetically identical plants—
one in the sun, one in the shade,
the sun-grown plant will produce seeds
that grow better in the sun
and the shaded plant will grow seeds
that grow better in the shade—
even though they’re genetically identical.
So what we’re dealing with is epigenetics,
external factors changing gene expression.
Vole pups born in the winter
come out growing thicker coats.
Vole mothers are able to communicate the season
to their babies in utero
and tell them to put a coat on
even before they’re born,
and people are no different.
You know how different people
have different temperature tolerances,
resulting in battles of the bedroom—
do you turn the AC on or off,
open the windows?
It’s not just genetics.
Whether you’re born in the tropics or in a cold environment
determines how many active sweat glands you have in your skin.
But what does this have to do with diet?
Can what a pregnant woman eats
permanently alter the biology of their children
in terms of what genes are turned on
or off throughout life?
Or what they don’t eat?
What happened to the children
born during the 1945 Dutch famine,
imposed by the Nazis?
Higher rates of obesity 50 years later.
The baby’s DNA gene expression reprogrammed before birth
to expect to be born into a world of famine,
to conserve calories at all cost,
but when the war ended,
this propensity to store fat
became a disadvantage.
What pregnant women eat and don’t eat
doesn’t just help determine the birth weight of the child,
but the future adult weight of the child.
For example, maternal protein intake during pregnancy
may play a role in the obesity epidemic,
but not just protein in general.
Protein from animal sources, primarily meat products,
consumed during pregnancy may increase the risk
of their children growing up overweight.
Originally they thought it might be the IGF-1,
a growth hormone boosted by animal product consumption
that may increase the production of fatty tissue,
but weight gain was tied more to meat than dairy.
Every daily portion of meat intake
during the third trimester
resulted in about an extra percent of body fat mass
in their children by their 16th birthday,
potentially increasing their risk
of becoming obese later in life,
independent of how many calories they ate
or how much they exercised.
But no such link was found with cow’s milk intake,
which would presumably boost IGF-1 levels just as high.
So maybe instead it’s the obesogens in meat,
the chemicals that stimulate the growth of fatty tissue.
Emerging evidence demonstrates that environmental factors
could predispose exposed individuals to gain weight,
irrespective of diet and exercise.
After all, even our infants are fatter—
you can’t blame that on diet and exercise.
Animals too.
And not just our pampered pets,
even rats in labs and subways.
The likelihood of 24 different animal populations
from eight different species
all showing a positive trend in weight
over the past few decades
by chance is less than one in a million,
and so it appears there’s something else going on,
like obesogenic chemicals.
One such candidate is polycyclic aromatic hydrocarbons
found in cigarettes,
spewing out of exhaust pipes, and in grilled meat.
This nationwide study of thousands
found that the more children are exposed,
the fatter they tended to be—
they could measure the levels of these chemicals
right out of their urine.
And it can start in the womb;
prenatal exposure to these chemicals
may cause increased fat mass gained during childhood
and a higher risk of childhood obesity.
If these pollutants sound familiar,
I’ve covered them before in relation to increasing breast cancer risk
in the Long Island Breast Cancer Study,
so maybe they're not just obesogens but carcinogens as well,
perhaps explaining the 47% increase
in breast cancer risk among older women
in relation to a lifetime average
of grilled and smoked foods.
If you look at one of the most common of these toxins,
smokers get about half from food, and half from cigarettes,
but for nonsmokers, 99% comes from diet.
The highest levels are found in meat,
with pork apparently worse than beef,
but as you can see, even dark green leafies like kale
can get contaminated by pollutants in the air,
so don’t forage your dandelion greens
next to the highway
and make sure to wash your greens under running water.
Now these are fat-soluble pollutants;
they need lots of fat to be absorbed,
so even heavily contaminated plant-based sources
may be safer,
unless you pour lots of oil on your food,
in which case the toxins would presumably become
as readily absorbed as the toxins in the meat.
The good news is that they don’t build up in your body.
If you expose people to barbecued chicken
at time zero here,
you can see they get a big spike in these chemicals
like up to a hundred-fold increase,
but your body can get rid of it within about 20 hours.
The problem of course is that people who eat these
kinds of foods every day
may be constantly exposing themselves,
which may not only affect their health
and their children’s health,
but maybe even their grandchildren’s health.
Being pregnant during the Dutch famine
didn’t just lead to an increase in diseases
among their kids, but even apparently their grandkids.
So, what a pregnant woman eats now
may affect future generations.
The issue of generation- spanning effects
of poor conditions during pregnancy
may help shed some light
on the explosive epidemics of diabetes, obesity,
cardiovascular disease associated with this transition
towards Western lifestyles.