The kidneys contain millions of nephrons, the units responsible for filtering approximately 43 gallons of water per day. Since the nephrons also filter minerals and wastes from the blood, what you eat has an impact on kidney health. What you eat also affects your chances of developing kidney stones. Making the right food and beverage choices can help preserve kidney function or reduce the risk of developing certain types of kidney stones.
Waste Products and Protein
Some metabolic reactions result in the creation of waste products in the blood. The muscles contain creatine, which produces a waste product called creatinine each time the muscle tissue contracts. The amount of protein you consume also affects creatinine levels, so limiting your protein intake keeps the kidneys from working too hard to eliminate creatinine from the blood. Approximately 20 to 30 percent of your calories should come from protein. Choose low-fat, low-cholesterol sources such as lean sirloin, low-fat dairy products and legumes.
Sodium
Sodium helps the body absorb nutrients, maintain normal fluid levels and control blood pressure. No one can survive without this mineral, but too much sodium in the diet has serious consequences for the kidneys. These organs work with the endocrine system to regulate the amount of sodium and fluid in the body. If the kidneys excrete too much sodium, fluid levels decrease and the risk of dehydration increases. If they retain too much sodium, the body also retains excess fluid. This causes fluid retention and increases in blood pressure. Consistent high blood pressure increases the risk for kidney damage. Limit high-sodium foods such as canned meats, potato chips, salted pretzels, canned soups, frozen entrees, canned vegetables, fast food and luncheon meats.
Potassium
Potassium has several benefits for those who have normal kidney function. Following a diet low in sodium and high in potassium reduces blood pressure. Potassium intake also has a positive result in those prone to forming kidney stones that contain calcium. Increasing potassium intake reduces the amount of calcium excreted in the urine. Since high urinary calcium excretion has a link to the formation of kidney stones, increased potassium intake could prevent stones from forming. Low-fat, low-calorie sources of potassium include bananas, oranges, spinach, yams, pumpkin, tomatoes and potatoes.
Low-Oxalate Foods
Some kidney stones contain calcium oxalate, so reducing the amount of oxalate in your diet helps prevent these stones from forming. The University of Pittsburgh Medical Center recommends limiting your oxalate intake to 40 to 50 mg per day. Limit the consumption of high-oxalate foods such as raspberries, chocolate, green peppers, potatoes, soy products, nuts and parsley. Cucumbers, mushrooms, milk, cheese, bananas, melons and cherries have low levels of oxalate.
Impaired Kidney Function
If you have impaired kidney function due to kidney disease or acute renal failure, you have special dietary needs. You need to limit your intake of protein and sodium, and also control the amount of potassium you consume each day. Damaged kidneys do not maintain normal potassium levels, so too much potassium builds up in the blood. This increases the risk for heart palpitations and cardiac arrest. Instead of eating high-potassium foods, choose foods with low or medium amounts of potassium. Instead of bananas, oranges, chocolate desserts and spinach, try apples, cherries, vanilla desserts and bell peppers.
References
- National Space Biomedical Research Institute: The Kidney
- Lab Tests Online: Creatinine
- Phoenix Fire Department Health Center; The Wellness Diet: Anti-Inflammatory Diet Basics and Diet Tips; September 2008
- Linus Pauling Institute; Sodium; Jane Higdon, et al.; February 2004
- Linus Pauling Institute; Potassium; Jane Higdon, et al.; February 2004
- University of Pittsburgh Medical Center; Low Oxalate Diet; 2006
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