The Role of Minerals
When we first start learning about nutrition — and just about every time we research it throughout our lives — we’re always told how important it is to get vitamins and minerals from the foods we eat. While that is true, it applies in a different way for people with kidney disease. When you digest food, minerals, other nutrients and water go into your bloodstream so your body can use them in the ways it needs to. If there are excess amounts of these substances, they remain in your blood and your kidneys filter them out, eventually excreting them as waste through your urine.
However, when you have kidney disease, it means these organs are damaged and are not as efficient at removing waste products from your blood. This can cause those toxins to build up in your blood instead of leaving your body like they need to do, which can create a wide range of other health issues. In particular, two minerals — potassium and phosphorus — tend to build up in the blood of people with kidney disease. Potassium is essential for helping your muscles and nerves work properly, but if much more of it than you need builds up in your body, it can cause weakness and cramps and keep your heart from beating normally. Phosphorus works with calcium and vitamin D to maintain bone health, but too much of it can actually weaken your bones and cause them to break more easily.
When you have kidney disease, it’s critical to work with your doctor to manage your intake of these minerals. Your physician may want you to limit your consumption of foods that can elevate your potassium and phosphorus levels so that your kidneys don’t need to work as hard at removing the minerals from your blood. One of the main roles your kidneys play is maintaining the proper balance of fluids, nutrients and minerals in your blood, but when their ability to do that is impaired due to damage, you may need to take over doing some of that work by making different diet choices.
Protein and Kidney Disease
Similar to eating high-potassium or high-phosphorus foods, getting a lot of protein in your diet can also cause excess waste products to build up in your blood because your damaged kidneys aren’t able to remove it efficiently. Depending on how far your kidney disease has progressed, you may need to limit the amount of protein you eat to prevent waste buildup from occurring. Getting too much protein can also worsen your kidney disease because this nutrient increases pressure in the tiny structures of your kidneys that filter out waste, wearing them down over time and limiting their ability to function.
In the earlier stages of kidney disease, doctors often recommend limiting the amount of protein you eat to put less stress on your kidneys and prevent more damage from happening. However, if your kidneys are in the later stages of disease and you’re on dialysis, you may need to increase your protein intake, particularly if you were on a lower-protein diet. This is because the dialysis treatment efficiently removes waste products from your blood, and you don’t want to become deficient in protein by eating too little of it.
Foods to Eat and Avoid on a Kidney-Friendly Diet
It’s important to remember that eating a kidney-friendly diet is all about balance. Your kidneys are usually responsible for maintaining the right balance of nutrients in your body, but you may need to make dietary choices that do some of this work for them. It’s also about eating a healthy balance of foods. Having kidney disease doesn’t mean you immediately have to stop eating everything with protein, phosphorus and potassium — that’ll only cause other health issues.
While it’s essential to work with your doctor and a dietician to determine what you should and shouldn’t eat in order to best manage your kidney disease, there are some foods that people with this condition are commonly recommended to eat — and avoid.
It can be helpful for people with kidney disease to eat foods that are lower in potassium and phosphorus. Fruits that are low in potassium include apples, grapes, cranberries and strawberries, and low-potassium vegetables to eat include radishes, cauliflower, onions, peppers, summer squash and lettuce. You may need to eat fewer fruits and vegetables like bananas, avocados, melons, prunes, potatoes and tomatoes, which are all higher in potassium. It’s also better to opt for white rice instead of the brown and wild varieties and stick with breads like pitas and tortillas instead of bran-heavy darker breads. Dairy products also tend to be higher in potassium, so you may need to reduce your intake of milk, yogurt and cheese.
Phosphorus is found in many foods, but it’s also in quite a few of the foods to avoid when you have kidney disease. That can simplify some of your diet choices if you need to limit your intake of both minerals. Low-phosphorus foods to enjoy include pasta, French and sourdough breads, unsalted popcorn, and corn and rice cereals. You’ll want to avoid dark whole-grain breads, bran cereals, granola, oatmeal, some dairy products and most nuts, which are all higher in phosphorus. Meat, poultry and fish tend to be higher in phosphorus, but fish, poultry and egg whites are generally better sources of protein for people with kidney disease.
It’s also important for people who have kidney disease to limit their sodium intake. This is because getting too much sodium can lead to high blood pressure, which can cause further kidney damage if left untreated. While some sodium is necessary for keeping your body healthy, the Journal of Renal Nutrition advises eating no more than 2,000 milligrams of sodium per day. Your doctor may recommend that you consume even less sodium daily, down to 1,500 or 750 milligrams, depending on your level of kidney damage. Look for low-sodium labeled foods while grocery shopping, and avoid seasoning your food with salt whenever possible — use herbs and sodium-free seasonings instead.