Animal Protein Damages Kidney Function
We hear it all the time: protein. If we're hungry midafternoon, our coworker wonders if we didn't include enough protein in our lunch. If we say we're feeling tired lately, our sister asks if we're eating enough protein. If we twist our ankle, our neighbor wants to know… Okay, that's an exaggeration, but you get the picture! More protein seems to be the automatic answer on everyone's lips. A high protein diet is touted as "the solution" for weight loss, and increased protein is supposedly the key to bulking up. It's ironic that protein is "recommended" for both losing and gaining weight. Yet despite the abundance of "healthy" protein in the typical American diet, the United States doesn't make the top ten list of healthiest nations in the world.
Protein is made up of twenty different amino acids. Eleven of them our body is able to manufacture. Nine of them we need to get from the food we eat, but we don't need all nine at the same meal (the notion of combining foods for complementary protein has long been debunked). If we are eating a wide variety of plant-based foods, it is nearly impossible to not get enough of the nine essential amino acids. Plants supply all necessary protein. Cows, horses, and elephants all build their muscles by eating plants. Humans can do the same. If we instead choose to get our essential amino acids from secondary sources like meat, eggs, and dairy products, these concentrated sources of protein lead us to take in more than the RDA of protein per day. If we additionally throw in a "protein bar" or some jerky as a snack between meals, mix up some protein powder in our après workout shake, and take the kids out for ice cream in the evening, we're off the charts on our protein intake. The average American consumes about twice the amount of protein needed. Is there such thing as eating too much protein? Can excess protein actually cause health problems? The answer is "yes." And one of the organs that bears the brunt of our excess protein intake is our kidneys.
Protein and an Acidic Environment
As organs of elimination, our kidneys process the excess protein we eat, eliminating it from our bodies via the urine. Interestingly, research indicates that it is not the amount of protein we eat that causes kidney problems, it is the type of protein we eat. Protein from plant sources is alkaline, whereas protein from animal sources is high in sulfur and thus produces an acidic environment. To counteract the acid, our kidneys produce ammonia, which is very base. It may be the acidic environment brought on by meat consumption, or it may be the prolonged exposure to ammonia that causes the damage to our kidneys. In either case, a full 13% of US adults have chronic kidney disease (CKD) and there is increased disease and death among those with only mild kidney disfunction. Kidney function generally begins to decline after our thirties. Citing the Nurses Health Study which followed 1,624 women, the Physician's Committee for Responsible Medicine (PCRM) states: "as many as one in four adults in the United States may already have reduced kidney function, suggesting that most people who have renal problems are unaware of that fact and do not realize that high-protein diets may put them at risk for further deterioration."
Protein and Kidney Stones
Protein is also implicated in the formation of painful kidney stones. Calcium forms the basis of the two most common types of kidney stones, so a low-calcium diet has been part of the standard recommendation for preventing recurrent kidney stones. Although this diet has been somewhat successful, researchers noted that a high-calcium diet also showed some success in lowering the incidence of repeat episodes. Could it be that something other than calcium was affecting the formation of these kidney stones? Researchers compared the effect of a diet with normal calcium intake but low in animal protein and salt to the standard low-calcium diet. Both groups were told to drink two to three liters of water per day. The subjects on a normal calcium, low-animal protein/low-salt diet experienced 50% lower risk of recurrent kidney stones. This study indicates that calcium intake is not the primary factor for those with a tendency to form kidney stones, but rather animal protein and salt are the larger determining factors.
Uric acid is the source for the next most common type of kidney stone. An acidic environment in the kidneys is the cause of the formation kidney stones made of uric acid, but dropping the acid-forming animal protein drops the risk of stones by 93%. In fact, for four out of the five types of kidney stones, eating a diet rich in vegetables and low in animal protein and salt -- plus drinking 10-12 cups of water daily -- is our best dietary solution for preventing kidney stones. The fifth type of kidney stone doesn't respond directly to diet because the stones are brought on by infection.
Protein and High Blood Pressure
Poor diet and high blood pressure are now the leading risk factors for death globally. Yet as Michael Greger, MD, points out in his video blog on preventing high blood pressure, we've known since 1929 that high blood pressure is not inevitable:
Researchers measured the blood pressure of a thousand people in rural Kenya who ate a diet centered around whole plant foods. Whole grains, beans, vegetables, fruit, and dark green leafy vegetables. Up until age 40, the blood pressures of rural Africans were about the same as Europeans and Americans, down around 120s over 80s, but as Westerners age, their pressures creep up such that by age 60 the average person is hypertensive, exceeding 140 over 90. But what about those not following the Western diet? Their pressures improved with age, not only did they not develop hypertension, their blood pressures actually got better.
High blood pressure is the second leading cause of kidney failure. The American Heart Association explains that "uncontrolled high blood pressure can cause the arteries to narrow, weaken, or harden." As organs of elimination, the kidneys are rich in blood vessels. The blood must pass through the kidneys so waste products can be removed from the bloodstream. If our blood pressure is elevated, over time the arteries in our kidneys become damaged, losing "their ability to filter blood and regulate the fluid, hormones, acids and salts in the body." Kidney disease and eventually kidney failure are the result of hypertension. Changing our eating habits to a whole-foods, plant-based diet free from added oil will lower our blood pressure, keeping us safe from the risks of kidney damage and failure due to hypertension.
Plant Foods Protect our Kidneys
"Modern researchers know that it is virtually impossible to design a calorie-sufficient diet based on unprocessed whole natural plant foods that is deficient in any of the amino acids," says dietician Jeff Novick, MS. Yet as a society, we are hurting our bodies in our quest to "make sure" that we are getting enough of this single macronutrient. Chronic kidney disease, kidney stones, and hypertension-induced kidney disease or failure represent the diseases suffered in just one of our body's many organs when we eat a typical Western diet rich in animal protein with its accompanying saturated fat and cholesterol. By contrast, eating a variety of whole plant foods without added oil will give us plenty of health-promoting plant protein, and doesn't carry the multiple risks associated with animal protein. If you'd like to begin protecting your kidneys, your heart, your brain, and your overall wellbeing, why not check out the HELP section of this website? There I offer suggestions on Getting Started with this lifestyle and suggest other resources that you'll find helpful. Also, you can join our Starch-Smart Community to find others who have already made the switch to a diet that will protect their kidneys and their health. They've learned how to do it, and so can you!
(8) Protein Overload
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