General Considerations and Tips
The kidneys play several important roles in human health, such as filtering blood, regulating mineral levels, maintaining hormone levels, and removing waste products. When they are damaged, all or some of these functions are affected, and it might be more difficult for liquids, excess minerals, and waste products to be eliminated from the body. This is when diet regulation comes in, as it is capable of excluding certain minerals and other nutrients typically processed by the kidneys and prevent further damage.
In addition, choosing foods good for kidney health will help improve kidney function. The extent to which you should limit certain foods will depend on the severity of the kidney damage, with serious cases requiring dialysis, a strict dietary regimen, and other medical interventions you ought to discuss with a doctor. Earlier stages of the disease, on the other hand, may require fewer dietary restrictions.
Some of the key dietary tips to keep in mind are:
1. Limiting daily sodium intake to 2g or less. This means avoiding added salt, soy sauce, packaged foods, and fast foods, among other things. Signs that your kidneys cannot filter out excess salt from your diet include high blood pressure, swollen ankles, and shortness of breath. In severe cases, fluids can build up in the heart and lungs.
2. Reducing Your Phosphorous Intake to about 1,000 mg a day. Phosphorous is essential for healthy bones and teeth, and it helps cells to repair themselves, but excess levels of the minerals that don't get filtered out by the kidneys may have the opposite effect and lead to an increased risk of heart disease. This is why dark-colored sodas are not recommended for people with damaged kidneys, as these often contain phosphorous.
3. Watching Your Potassium Intake. Potassium is another mineral regulated by the kidneys. While it is important to keep your muscles healthy, excessive levels of potassium (over 2,000 mg a day) in the blood can lead to serious heart issues, so it is recommended to watch your potassium level if you suffer from significant kidney damage.
Below, we list 14 generally healthy foods that contain a lot of sodium, potassium, phosphorous, or other ingredients that can be harmful to those suffering from kidney issues.
Bananas are well known for their high potassium levels, with just one medium fruit containing 422 mg of potassium on average. If you want to keep your potassium intake below 2,000 mg a day, it may be difficult when eating this tropical fruit. Other tropical fruits that also contain a lot of potassium are pomegranates and coconut water, to name a few.
It's not just spinach that can harm your kidneys, other leafy greens like Swiss chard and beet greens have a similar nutrient profile. Like bananas, these greens are high in potassium, with 1 cup of the fresh greens containing up to 290 mg. In addition, these greens contain a lot of oxalates, which can accumulate in the kidneys and cause kidney stones, reducing the kidney function even further.
Cooking spinach will not reduce its potassium content, and it can be quite easy to consume a lot of it in cooked dishes that contain some spinach (e.g. 1 cup of spinach reduces to just 2 tablespoons of cooked spinach).
3. Certain Dried Fruit
Dried fruits are a common healthy snack, with dietitians often recommending them instead of sweet treats. However, many varieties of dried fruit can contain a lot of potassium in a relatively small volume, so it's easy to increase the recommended daily intake of potassium while snacking on dried fruit. For example, just 2 pitted dates containing 334 mg of potassium. Other dried fruit high in the mineral are prunes, raisins, and dried apricots.
The dried fruit most beneficial for those suffering from kidney problems is dried cranberries, a 1/3 cup serving of which contains just 16 mg of potassium.
4. Brown Rice
Brown rice is a whole grain that's quite high in both potassium and phosphorous, with just one 1/2-cup serving of cooked brown rice having 78 mg of potassium and 75 mg of phosphorus. Processing reduces the amount of these minerals in rice, so the same serving of white rice will contain just 35 mg of phosphorus and 29 mg of potassium.
Still, white rice also contains less of the other nutrients, so instead of replacing brown rice with white rice, it's better to opt for other grains, such as buckwheat, bulgur, or couscous, that both have a much lower phosphorus content and contain other beneficial ingredients. Keep in mind that the popular grain, quinoa, is even higher in phosphorus and potassium than brown rice, so it's not a good replacement.
5. Oranges and Orange Juice
Like other tropical fruit, citrus fruit, especially oranges and grapefruit, contain a lot of potassium, as do their juices.
One orange or grapefruit both contain around 333 mg of potassium. Just one 240 ml cup of orange juice contains even more - 473 mg of potassium, which is more than a quarter of your daily intake of the mineral.
You can replace orange juice and the fruit itself, you can opt for grape, apple, or cranberry juice and the respective fruit, all of which are more beneficial for the kidneys.
6. Canned Foods
The main problem with canned foods when it comes to kidney health is the high sodium content. Salt is necessary for preserving foods for a long time, so there is no way to avoid it, especially if you're dealing with canned soups or readymade meals. If you depend a lot on these foods, it's best to choose the low-sodium varieties when shopping for canned goods.
You can also rinse canned vegetables, like peas, beans, and tuna with water before eating them, which can reduce the sodium content by 33–80%.
7. Seafood and Other Animal Sources of Protein
People with serious cases of kidney damage are often asked to reduce their intake of animal protein, such as red meat and poultry, but especially seafood, mainly because chronic kidney damage can reduce how well the body can eliminate protein side products. Needless to say, processed meats are off the table, too, as these typically contain way too much salt even for people without any kidney problems. Dairy products are likewise not recommended, as they contain phosphorous and potassium in high quantities, and certain cheese varieties can also be quite high in sodium.
Certain seafood varieties, such as mollusks, squid, and octopus can also contain up to 85% of the recommended daily intake of phosphorous in just one serving, so they can be quite difficult to incorporate into a low-phosphorus diet. Also be wary of canned fish, which can be high in salt content.
Apricots are another fruit people with a renal diet should best avoid, since both dried and fresh apricots are quite high in potassium: 1 cup of fresh apricots has 427 mg of potassium, on average. The same applies to apricot juice or nectar, so we recommend opting for some of the kidney-friendly juice substitutes we mentioned earlier.
9. Olives and Pickles
Fermented foods like kimchi, olives, pickles, and sauerkraut can do amazing things for one's gut health, but fermentation, unfortunately, requires the use of plenty of salt, rendering these foods potentially harmful for people with kidney problems. To put things in perspective, depending on the brine, 1 pickle spear can sometimes contain as much as 300 mg of sodium, or even more. Be wary of low-sodium varieties of pickled foods, too, as even these are often unsafe for those on a renal diet.
10. Whole Wheat Bread
Normally, whole grain bread is considered a healthier choice, but the same rule doesn't apply to those with damaged kidneys. Like brown rice, whole wheat bread is made of whole grains, which may contain a lot more beneficial nutrients and fiber than white bread, but along with it also comes double the amount of potassium and phosphorus, too.
Thus, those who are watching their potassium and phosphorus intake should actually opt for white bread, which is somewhat counterintuitive. You can also try other bread varieties that don't contain wheat, such as cornbread but make sure to take sodium content into account, too, as most bread varieties do contain a lot of salt.
Tomatoes are another one of those staple foods that are, unfortunately, unavailable to those on a renal diet since they contain a lot of potassium: 1 cup of tomato sauce contains over 900 mg of it. You can replace a tomato sauce with a roasted red pepper sauce to go with pasta or other dishes, which offers significantly less potassium per serving.
12. Certain Breakfast Cereals
Choosing a breakfast cereal can be a daunting task for those with chronic kidney problems, as many cereal varieties available on the market contain dangerously high levels of potassium. In addition, a recent study conducted by the National Renal Foundation also showed that many companies misrepresent potassium levels in their products.
For this reason, opting for breakfast cereals made of corn or rice flour is the safest choice for those suffering from kidney problems, as the whole wheat or whole oatmeal choices typically contain more significant potassium.
13. Potatoes and Sweet Potatoes
Potatoes and sweet potatoes are among the most potassium-rich vegetables, with 1 medium baked potato offering 610 mg of potassium, a similar sweet potato containing only slightly less - 541 mg. Luckily, there is a trick that will help you reduce potassium levels in potatoes and yams by 50%.
Soaking and boiling the vegetable will help reduce its potassium content: simply cut the vegetable into thin pieces and soak for several hours, and then boil them for at least 10 minutes. Do keep in mind that you will still need to control the portion of the potatoes and yams you consume, even if you soak them.
The last, but definitely not the least item on this list is the avocado - a constant feature in healthy recipes. Unfortunately, avocados are also among the most potassium-rich foods, period, containing more than double the amount of the mineral compared to bananas. 1 cup of avocado contains 727 mg of potassium, more than a third of the recommended daily intake for people with chronic kidney damage, so try to stay away from them.