“In the United States, approximately one in three adults aged 65 years and older has chronic kidney disease (CKD),” as I note in my video Treating Chronic Kidney Disease with Food, but the “majority of patients with CKD do not progress to advanced stages of CKD because death precedes the progression to end-stage renal disease…” Following about a thousand folks 65 years or older with chronic kidney disease for about a decade, only a few had to go on dialysis because most died. The scariest thing for many kidney patients is the fear of dialysis, but they may be 13 times more likely to die than go on dialysis. With heart disease killing more than nearly all other causes combined, decreasing kidney function can set one up for heart attacks, strokes, and death.
That’s why it’s critical that any diet chosen to help the kidneys must also help the heart. A plant-based diet fits the bill, providing protection against kidney stones, kidney inflammation, and acidosis, as well as heart disease. (See below for links to my videos covering these very topics.) That is, “blood pressure control may be favored by the reduction of sodium intake and by the vegetarian nature of the diet, which is very important also for lowering serum cholesterol,” which may not only help the heart but also the kidneys themselves.
In 1858, Rudolf Virchow, the father of modern pathology, was the first to describe the fatty degeneration of the kidney. In 1982, this idea of lipid nephrotoxicity—the possibility that fat and cholesterol in the bloodstream could be toxic to the kidneys directly, based on data showing plugs of fat literally clogging up the works in autopsied kidneys—was formalized.
Since the notion was put forth, it has gained momentum. It appears high cholesterol and fat in the bloodstream may accelerate the progression of chronic kidney disease through direct toxic effects on the kidney cells themselves. Given the connection between cholesterol and kidney decline, the use of cholesterol-lowering statin drugs has been recommended to slow the progression of kidney disease. Of course, “[s]erious adverse effects on muscle and liver must be kept in mind.” This is why plant-based diets could offer the best of both worlds, protecting the heart and the kidneys without drug side effects.
The two potential drawbacks are the amount of phosphorus and potassium in plant foods, which ailing kidneys can sometimes have a problem getting rid of. It turns out, however, that the phosphorus in meat is absorbed at about twice the rate, not to mention the phosphate additives that are injected into meat. So, eating plant-based can significantly lower phosphorus levels in the blood. The concern about potassium is largely theoretical because the alkalinizing effects of plant foods help the body excrete potassium, but it is not theoretical for those on dialysis or with end-stage disease who need to be closely followed by a dietician kidney specialist.
Special protein-restricted vegan diets have been used successfully to slow or stop the progression of kidney failure. One study showed the declining kidney function of eight diabetics for one to two years before switching to the plant-based diet, which appeared to stop the inexorable decline in most of the patients. This led the researchers to proclaim it as the treatment of choice for diabetic kidney failure.
Strictly plant-based diets may also help delay dialysis by one to two years and, after kidney transplant, may improve the survival of the kidney and improve the survival of the patient. Most of the papers, though, are just pilot feasibility studies. It doesn’t matter if it’s effective if we can’t get people to stick to the diet. But while we’re waiting for more definitive studies, existing data support offering these kinds of plant-based diets as an option to all patients with advanced or progressive chronic kidney disease.
“[E]ven if the effects of such diets on the progression of renal failure are still debatable, the unquestionably favorable effects [of plant-based diets] on some of the most deleterious cardiovascular and metabolic disorders usually associated with renal failure,” such as hypertension and diabetes, “provide rationale for recommending a predominance of proteins from a vegetable source” for patients with failing kidneys.
Yet, diet is still underutilized, in part because some people find changing their diet is difficult. Yet, we know foods rich in animal protein lead to metabolic acidosis. Our diets “are largely acid-producing because they are deficient in fruits and vegetables and contain large amounts of animal products.” So, what did doctors do? They gave people baking soda. Instead of treating the cause––the dietary acid load from too many animal products and too few fruits and vegetables––they treated the consequence by saying, “Oh, too much acid? We’ll just give you some base: sodium bicarbonate.” And it works. Neutralization of dietary acid with sodium bicarbonate decreases kidney injury and slows kidney function decline, but sodium bicarbonate (baking soda) has sodium, so doctors may be just adding another problem.
If patients are not going to cut back on animal products, they should at least be eating more fruits and vegetables. They tried that, and it worked, too, and did so without leading to too much potassium in the blood. In fact, it may even work better because fruits and vegetables have the additional advantage of helping to lower blood pressure. The study that examined this is important because it illustrated a simple and safe way to treat metabolic acidosis: with fruits and vegetables. So, the key to halting the progression of chronic kidney disease might be in the produce market or the farmer’s market, not in the pharmacy.
This is the last in an extended six-part series on the latest science on diet and kidney health. Check out the rest of the series:
You have to have functioning kidneys to keep you in balance. The problem for most people is not getting enough potassium, which I discuss in my video 98% of American Diets Potassium Deficient, but too much phosphorus in the blood can also be a problem. Thus, phosphate additives are something we should try to avoid. For more on this, see:
Michael Greger, M.D.
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