Diet and Kidney Disease

Today more than 400,000 Americans have stage 5 kidney disease. Stage 5 kidney disease is also known as end stage renal disease (ESRD). It is characterized by the near total loss of kidney function. The vast majority of Americans with failed kidneys end up on dialysis but about 20,000 Americans are now living with the help of someone else’s kidney. Unfortunately, once kidneys have failed there is no way to restore their function so dialysis is for life except for a lucky few for whom a kidney transplant is an option. However, there are another approximately 20 million Americans who have Stage 1 kidney disease. These people usually have no symptoms and most Americans in the early stages of kidney disease are not even aware that their kidney function is deteriorating. This is unfortunate because early damage to the kidneys can be largely reversed or at least dramatically slowed in most cases. There are many reasons kidneys fail.The vast majority of people who end up with end up with ESRD do so as a result of diabetes, hypertension, obesity, and dyslipidemia (low HDL and high triglyceride levels). The risk factors for diet-promoted renal disease are very similar to those associated with heightened risk of cardiovascular disease (CVD). The typical American diet is high in fatty animal products, salt, and sugar and low in whole grains, vegetables, fruits, and seafood. This typical American diet has long been known to promote CVD and it is now known that these same dietary insults and metabolic abnormalities they create also promote chronic kidney disease.The vast majority of patients with failed kidneys who have access to dialysis (nearly all Americans do) die from CVD so the importance of a healthy diet for those with early renal disease is apparent. Indeed, between 10 and 20% of people on dialysis die each year and in the vast majority of cases those deaths are from CVD.Early renal disease can be diagnosed by finding small amounts of the blood protein albumin in the urine (microalbuminuria) and/or by finding elevated levels of creatinine and urea (blood urea nitrogen – BUN) in the patient’s blood. The typical modern diet leads to cholesterol deposits in the artery wall leading to inflammation and eventually atherosclerosis. Most of the same dietary induced metabolic insults that damage and thicken arteries also damage blood vessels in the kidney’s filtering apparatus known as the glomerulus. Recent research shows that the build up of cholesterol in the small blood vessels of the glomerulus leads to inflammation and sclerosis. Dietary and metabolic insults that damage these filtering units lead to glomerulosclerosis. The result of this progressive damage to these blood-filtering units is a reduced ability to clear waste products from the blood.1Recently, it has been proposed that diets high in fructose contribute to hypertension, dyslipidemia, weight gain, insulin resistance, type 2 diabetes, atherosclerosis, and renal damage that can eventually lead to failing kidneys. It has long been known that fructose increases uric acid production and it is now being proposed that elevated uric acid levels may play a role in sclerotic diseases because it stimulates the production of inflammatory cytokines and a reduction in nitric oxide.2The Bottom LineWhile it may take time to figure out precisely how the modern diet leads to failing kidneys we certainly know enough to plan diets than can help prevent most of those with early renal disease from progressing to ESRD.By James J. Kenney, PhD, RD, FACNReferences:1 J Am Soc Nephrol 2003;14:593-6002 Am J Clin Nutr 2007;86:899-906The Best Diet For Kidney HealthThe best diet to prevent kidney failure and heart disease is one that also promotes better health overall, helps you manage your weight and feel your best. It is made up more of whole foods rather than refined/prepared foods that have a lot of sugar, fat and sodium added.Your daily checklist of food for optimal eating:• 5 ounces of low-sodium whole grains - 1/2 cup cooked oatmeal, brown rice, barley, bulgur, whole wheat couscous or whole wheat pasta• 2-3 cups vegetables (mostly nonstarchy)• 2-3 cups of unsweetened fruit• 2-3 cups of nonfat milk or yogurt• 1-2 servings of nuts, seeds, legumes, fish, poultry or lean meat. Limit animal protein to one lean serving per day for optimal heart health. Work on increasing your consumption of beans.Limit or avoid these foods:• Foods with a high amount (more than 5% Daily Value) of saturated fat or cholesterol• Foods with trans fat (fried foods, many prepared foods and packaged crackers an cookies)• Foods with too much sodium (more than 1 mg of sodium per calorie or more than 5% of the Daily Value)• Foods with a lot of added sugar, especially foods that list sugar in the top 3 ingredients.