"How to Treat Heart Failure and Kidney Failure with Diet"
One way a diet rich in animal sourced foods—meat, eggs, and cheese—
may contribute to heart disease, stroke, and death
is through the production of an atherosclerosis-inducing substance
called TMAO.
With the help of certain gut bacteria,
the choline and carnitine found concentrated in animal products
can get converted into TMAO.
But wait a second:
I thought atherosclerosis, hardening of the arteries,
was about the buildup of cholesterol.
Cholesterol is still king.
TMAO just appears to accelerate the process.
TMAO appears to increase the ability of inflammatory cells
within the atherosclerotic plaque in the artery wall
to bind to LDL cholesterol, which makes them more prone
to gobble up that cholesterol.
So, it’s just another piece of the puzzle
of how cholesterol causes heart disease.
And, TMAO doesn’t just appear to worsen atherosclerosis,
contributing to strokes and heart attacks,
but also heart failure and kidney failure.
If you look at a really high risk group,
like diabetics after a heart attack,
nearly all those who started out with the most TMAO in their bloodstream
went on to develop heart failure within 2000 days—
about 5 years,
whereas only about 20% of those starting out with medium levels
in the blood went into heart failure
and none in the low TMAO group.
Not only do those with heart failure
have higher levels of TMAO than controls,
and those with worse heart failure have higher levels
than those with lesser stage disease,
if you follow people with heart failure over time,
within 6 years, half of those who started out with the highest levels
were dead.
This finding has since been replicated
in two other independent populations of heart failure patients.
The question is, why?
It’s probably unlikely to just be additional atherosclerosis,
since that takes years.
For most of those that die of heart failure, the heart muscle just conks out
or there’s a fatal heart rhythm;
so, maybe TMAO has toxic effects beyond just
the accelerated buildup of cholesterol.
What about kidney failure?
People with chronic kidney disease are at particularly increased risk
for the development of cardiovascular disease,
thought to be because of a diverse array of uremic toxins.
These are toxins that would normally be filtered out
by the kidneys into the urine, but may build up
in the bloodstream as our kidney function declines.
When we think of uremic toxins, we usually think of the toxic byproducts
of protein putrefying in our gut,
which is why specially formulated plant based diets
have been used for decades to treat chronic kidney failure.
Those who eat vegetarian form less than half
of these uremic toxins in the first place.
But those aren’t the only uremic toxins.
TMAO from the breakdown of choline and carnitine,
in mostly meat and eggs, may be increasing heart disease risk
in kidney patients as well by apparently down regulating
reverse cholesterol transport,
meaning subverting our own bodies’ attempt at pulling
cholesterol out of our arteries.
And indeed, the worse our kidney function gets,
the higher our TMAO levels rise,
and those elevated levels correlate with the amount of plaque
they have clogging up the arteries in their heart.
But, get a kidney transplant, get a working kidney going
and you can drop your TMAO levels right back down.
So, TMAO was thought to be kind of a biomarker
for declining kidney function.
But then, this study was published from the Framingham Heart Study,
which found that elevated choline and TMAO levels
among individuals with normal kidney function predicted increased risk
for developing chronic kidney disease,
suggesting TMAO is both a biomarker and itself a kidney toxin.
Indeed, when you follow kidney patients over time
and assess their freedom from death,
those with higher TMAO, even controlling for kidney function,
lived significantly shorter lives,
indicating this is a diet-induced mechanism for progressive
kidney scarring and dysfunction,
strongly implying the need to focus preventive efforts
on dietary modification.
What might that look like?
Well, maybe we should reduce dietary sources of TMAO generation,
such as some species of deep sea fishes, eggs, and meat.
But, it also depends on what kind of gut bacteria you have.
Remember, you can feed a vegan a steak, and they still don’t really make any TMAO,
because they haven’t been fostering
the carnitine-eating bacteria in their gut.
Researchers are hoping, however, that one day, they’ll find a way
to replicate the effects of a vegetarian diet
by selective prebiotic, probiotic, or antibiotic therapies.