"How to Prevent and Treat Kidney Stones with Diet"
This is what the surface of a kidney stone looks like under a microscope.
Imagine that scraping down your urinary canal.
Kidney stones affect approximately 1 in 11 people in the United States,
though 20 years ago it was only 1 in 20,
a dramatic increase in the prevalence of this disease
that started going up after World War II.
Our first clue as to why was published in the 70’s.
A striking relationship was found between stone incidence
and the consumption of animal protein.
But this was a population study, though—
you can’t prove cause and effect.
So next, researchers in Britain did an interventional study,
added animal protein to their diet,
like an extra can of tuna fish to their daily diet
and measured stone-forming risk factors in their urine:
how much calcium they were peeing out,
the concentration of oxalate and uric acid in their urine before,
...and after the extra tuna.
Their overall probability of forming stones increased 250%
during those days they were eating that extra fish.
And that so-called high animal protein diet?
That was just enough to bring intake up
to that of the average American.
So the average American intake of meat
appears to markedly increase risk of kidney stones.
So what about no meat?
Well, even by the late 70’s we knew that the only dietary factor
consistently associated with kidney stones was animal protein.
And not just getting your first kidney stone.
The higher the intake of animal protein,
the more likely an individual is to have multiple stones
rather than just one single stone episode.
Not protein in general, it seems,
but specifically high in animal protein.
Conversely, a diet low in animal protein may reduce
the overall probability of forming stones to become very low indeed,
which may explain the apparent low incidence
of stones in vegetarian societies,
so it may be worthwhile advocating a more vegetarian form
of diet as a means of reducing the risk.
But it wasn’t until 2014 when actual vegetarians were studied in detail.
Using hospital admissions data, they found that vegetarians
were indeed at lower risk of being hospitalized for kidney stones
compared to those that ate meat,
and among meat-eaters, increasing meat intake is associated
with a higher risk of developing kidney stones,
whereas, a high intake of fresh fruit, fiber, and magnesium
may reduce the risk.
We can use this information to advise the public
about prevention of kidney stone formation.
What advice should we give
in terms of which animal protein is the worst?
Despite compelling evidence that excessive animal protein consumption
enhances the risk of stone formation,
the effect of different sources of animal protein
had not been explored until this study was published in 2014.
People who form kidney stones are commonly advised
to restrict the intake of red meat to decrease stone risk,
but what about chicken and fish?
We didn’t know...
until now.
Salmon and cod were compared to chicken breast meat,
and burger and steak.
They found that gram per gram
fish may actually be worse,
in terms of uric acid production.
However, the overall effects were complex.
Basically, stone formers should be counseled
to limit the intake of ALL animal proteins,
and not just a little bit.
Only those who markedly decrease their animal protein intake
may expect to benefit from dietary recommendations.
Studies suggest that excessive animal protein consumption
poses a risk of kidney stone formation,
likely due to the acid load provided by the high content
of sulfur-containing amino acids in animal protein,
as I explored in my video on preventing kidney stones with diet.
But what about treating kidney stones?
Most stones are calcium oxalate,
formed like rock candy when the urine becomes supersaturated,
so doctors just assumed if they're made out of calcium
we just have to tell people to reduce their calcium intake.
So that was like the dietary gospel for kidney stone sufferers
until this study was published in the New England Journal of Medicine,
pitting the two diets against one another:
low calcium versus low animal protein and salt,
and it was the restriction of animal protein and salt
that provided greater protection,
cutting the risk of having another kidney stone within five years in half.
What about cutting down on oxalates,
which are concentrated in certain vegetables?
A recent study found that there was no increased risk
of stone formation with higher vegetable intake.
In fact, greater dietary intake of whole plant foods, fruits and vegetables,
were each associated with a reduced risk independent
of other known risk factors for kidney stones,
meaning one may get additional benefits
bulking up on plant foods in addition to just restricting animal foods.
The reason a reduction in animal protein helps
is not only because it reduces the production of acids within the body,
a reduction of animal protein should also limit the excretion of urate,
uric acid crystals that can act as a seed to form calcium stones,
or can create entire stones themselves.
Uric acid stones are the second most common kidney stones after calcium.
There's two ways to reduce uric acid levels in the urine:
a reduction in animal protein ingestion, or drugs.
And removing all meat can remove 93% of uric acid crystallization risk.
Here's the risk of crystals forming eating the standard Western diet for five days,
and then switching to a vegetarian diet: leads to a 93% drop in risk within days.
To minimize uric acid crystallization,
the goal is to get the urine pH up to ideally as high as 6.8,
so a number of alkalinizing chemicals have been developed,
but we can naturally alkalize our urine
up to the recommended 6.8 using purely dietary means,
namely, by removing all meat,
which takes someone eating the standard Western diet
up from an acid 5.95 right up to the target of 6.8 eating a vegetarian diet.
You can inexpensively test your own diet with a little bathroom chemistry,
for not all plant foods are alkalinizing, and
not all animal foods are equally acidifying.
A so-called LAKE score was developed: a Load of Acid to Kidney score,
which takes into account both the acid load of foods
and their typical serving sizes,
and can be used to help people modify their diet for the prevention
of both uric acid and calcium kidney stones and other diseases.
This is what they found.
The single most acid producing food was fish, like tuna.
Then pork, then poultry, then cheese,
though milk and other dairy only rates down here.
Then comes beef.
Now eggs are actually more acidic than beef, more acid forming,
but people tend to eat less eggs at a sitting, so they come in here.
Some grains can be a little acid forming,
such as bread, rice, but not pasta, interestingly.
Beans are significantly alkaline-forming,
but not as much as fruits, and vegetables are the most alkaline forming of all foods.
Through dietary changes alone we may be able to dissolve
uric acid stones away completely.
Cure them.
Now you see it, now you don't.
No drugs, no surgery.
Just telling them to drink more water and modify their diet,
such as restricting the intake of animal protein
and the kidney stone was gone.
To summarize, here are the five types of kidney stones.
And the most important things we can do diet-wise
is to drink 10 to 12 cups of water a day
and reduce animal protein, reduce salt,
eat more vegetables, and more vegetarian.