Transcript: How to Treat Kidney Stones with Diet
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 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 in 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 are 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 rate down here; then comes beef. Eggs are actually more acidic than beef, 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, 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 are to drink 10 to 12 cups of water a day, and reduce animal protein, reduce salt, eat more vegetables, and more vegetarian.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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