If You Have Bad Kidneys, Avoid These Foods

According to the National Kidney Foundation, 15% of people in the United States have kidney disease. Around 90% of patients with chronic kidney disease (CKD) don’t even know that they have it. Kidneys remove waste from the body, and it is critical to take care of them.

If you have or have had renal disease, such as kidney stones, you may want to change your diet. Even some healthy foods like nuts can make the condition worse. Read on to see all of the foods you should limit or avoid if you have bad kidneys.

Avoid Dark-Colored Soda And Choose Clear Soda

Coca cola pours from a bottle into a glass.
Dan Kitwood/Getty Images
Dan Kitwood/Getty Images

What’s the difference between dark-colored soda and light-colored soda? Dark soda has additives that create the caramel color. In this artificial color, there is phosphoric acid. This can harm the kidneys in large amounts, says the University of Virginia Health System.

Artificial phosphoric acid is different from natural phosphorus. According to the American Journal of Clinical Nutrition, phosphoric acid takes the form of salt and is easily absorbed. So along with sugar, you receive unhealthy salt from dark-colored soda. Your kidneys will not enjoy it.

Watch Out For Artificial Sweeteners Containing Aspartame

Splenda packets are in a clear plastic container on a coffee bar.
Richard Levine/Corbis via Getty Images
Richard Levine/Corbis via Getty Images

Artificial sweeteners can help people lower their sugar intake. However, a major ingredient in these sweeteners, aspartame, can harm your kidneys. In 2017, researchers examined multiple studies on the ingredient between 1980 and 2016. They concluded that aspartame injures the kidneys over time.

Aspartame creates inflammation in the kidneys that could worsen renal disease. That said, the FDA has approved some artificial sweeteners for CDK patients. Sucralose and Acesulfame-K are generally safe as long as you limit your potassium intake.

Avocados Have Too Much Potassium

A cut open avocado is seen on a pile of whole avocados.
John Tlumacki/The Boston Globe via Getty Images
John Tlumacki/The Boston Globe via Getty Images

Avocados are a delicious source of healthy fats and vitamins. But believe it or not, avocados have twice as much potassium as a medium banana. Too much potassium is especially bad for people with kidney disease.

According to the American Kidney Fund, people with kidney disease have a harder time breaking down potassium. If you have bad kidneys, you are at risk of developing high potassium, or hyperkalemia. You don’t have to avoid avocados entirely, but you may want to limit how much you eat.

How Sardines Can Cause Kidney Stones

Cans of sardines are stacked on top of each other.
Romulo Yanes/Condé Nast via Getty Images
Romulo Yanes/Condé Nast via Getty Images

If you have a high risk of kidney stones, you may want to avoid sardines. Sardines contain a high amount of purines. According to a 2019 study in Nutrients, purines convert to uric acid inside the body, which accelerates the growth of kidney stones.

Cleveland Clinic says that uric acid stones are one of the four major types of kidney stones. Other canned fish, such as herring, muscles, and anchovies, also contain purines, and you may want to limit these foods.

Soak Potatoes Before Eating Them

Peeled potatoes soak in water.
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Potatoes can fit into a renal diet if you cook them correctly. On their own, potatoes have a high amount of potassium that could overload the kidneys. One medium potato has a whopping 897 mg of potassium, coming out to 317 mg per half a cup.

Some people get rid of the potassium by soaking the potatoes. However, a study in the Journal of Renal Nutrition found that soaking them before cooking doesn’t work. Soak potatoes after normal cooking to remove 70% of the potassium, and don’t fry them.

How Instant Noodles Lead To Kidney Disease

A woman eats instant noodles out of a container.
Zhang Peng/LightRocket via Getty Images
Zhang Peng/LightRocket via Getty Images

In 2015, two patients visited a nephrology doctor in Taiwan. The patients required dialysis after eating a week’s worth of instant noodles. Both had underlying kidney illnesses, and the sodium from instant noodles made it far worse.

According to The Korean Nutrition Society, people who eat instant noodles tend to have a less healthy diet overall. They consume fewer vegetables, fruits, and whole grains. Avoid pre-packaged noodles for both your kidney health and your overall health.

Don’t Go Nuts With Peanuts

Dozens of salted peanuts sit in a bowl.
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Rafa Samano/Cover/Getty Images

Peanuts are healthy on their own, but they pose a risk for people who have a history of kidney stones. Peanuts contain calcium oxalate, the same mineral found in kidney stones. Your kidneys may not react well to too much calcium oxalate.

In 2014, researchers recorded a study on peanuts in Kidney Research and Clinical Practice. They found that peanut oxalates can aggravate kidneys, but it is highly unlikely that people will develop a kidney stone from peanuts alone.

In Extreme Cases, Ditch Whole Grain Bread

A customer reaches to grab whole-grain sourdough bread loaves.
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Usually, doctors advise people to replace white bread with whole-grain because it contains less sugar and more fiber. But people in the late stages of kidney disease may want to avoid or limit whole grains. According to the National Kidney Foundation, the reason is that whole wheat bread contains more phosphorus and potassium.

When kidneys suffer from illness, they struggle to filter through certain nutrients. Hence, patients have a higher risk of having high potassium or phosphorus. In this scenario, patients may want to eat white bread instead.

Don’t Waste Your Money On These Vegetable Oils

Bottles of vegetable oil stand in a row.
Matthew Horwood/Getty Images
Matthew Horwood/Getty Images

Cooking oils don’t have potassium, phosphorus, or oxalates to harm the kidneys. But some of them have a new threat: omega-6 fatty acids. Unlike omega-3 fatty acids, omega-6s are detrimental to kidney health, according to The Journal of Laboratory and Clinical Medicine.

Vegetable oils with high omega-6 include safflower oil, corn oil, sunflower oil, and soybean oil. Replace these with cooking oils that have high omega-3s, like olive and avocado oils. Omega-3 fatty acids can help your kidneys.

The Heightened Risks Of Red Meat

Two steaks of raw uncooked angus beef sit on a plate.
Natasha Breen/REDA&CO/Universal Images Group via Getty Images
Natasha Breen/REDA&CO/Universal Images Group via Getty Images

If you frequently eat red meat, your kidneys may struggle in the future. A 2016 study discovered that people who consume a lot of red meat have a 40% higher risk of kidney disease. Of all red meat, the worst culprit was pork.

Meat contains high amounts of acids that the kidneys take a while to break down. If you eat more meat than the time it takes for kidneys to process it, then you’ll have an excess of this acid. Eating more plant-based protein can prevent this.

Pickles Are Worse Than Just Salt

Pickle jars receive a hot vinegar bath in a factory.
JEAN-FRANCOIS MONIER/AFP via Getty Images
JEAN-FRANCOIS MONIER/AFP via Getty Images

Pickles have a high amount of sodium; one spear pickle contains a whopping 300 mg of salt. St. Michael’s Unity Health says that excess salt can contribute to kidney stones. Excess sodium heightens the amount of calcium in urine, which can create kidney stones.

Pickles may not have oxalate, but they increase the amount of oxalate in the kidneys. When kidneys have higher calcium, oxalate “sticks” to the calcium and forms kidney stones. To avoid this, don’t eat too many pickles.

Miso Soup Raises The Risk Of Renal Disease

Miso soup sits on a bowl with chopsticks on top of it.
Natasha Breen/REDA&CO/Universal Images Group via Getty Images
Natasha Breen/REDA&CO/Universal Images Group via Getty Images

Made of soybean paste, sea salt and rice koji, miso soup is usually a healthy appetizer choice. But it has too much salt for people suffering from kidney ailments. In fact, a 2015 study in Internal Medicine found that the Japanese have high rates of chronic kidney disease because of excess salt.

Miso soup has more salt than other soups. The University of California, Davis advises people with renal disease to avoid miso soup, as well as soy sauce and tempura sauce.

Jump From Whole Milk To Low-Fat Milk

Milk pours from a bottle into a glass.
Mayall/ullstein bild via Getty Images
Mayall/ullstein bild via Getty Images

In 2018, research in the scientific journal Nutrition examined seven studies on the relationship between milk and chronic kidney disease. In most studies, a high amount of dairy fat led to worse kidney health. Whole-milk can even raise peoples’ risk of renal disease.

On the other hand, low-fat milk is healthy for kidneys. They need a decent amount of calcium to function. But if you have renal issues, you may need to limit the amount of phosphorus you consume from milk. Limit dairy consumption to occasional low-fat products.

If You Have Renal Issues, Stick To One Cup A Day

A barista pours coffee into a blue mug.
LUIS ACOSTA/AFP via Getty Images
LUIS ACOSTA/AFP via Getty Images

If you have a high chance of developing kidney stones, then you may want to limit your coffee intake. In 2014, researchers discovered that drinking caffeine could hasten the formation of kidney stones. After people drink coffee, they urinate more, which raises the risk of stones.

On the other hand, coffee does not pose a risk for people with kidney disease. The National Kidney Foundation says that people with chronic kidney disease can safely drink coffee in moderation.

Why You Should Replace Processed Meats

A variety of processed meats are on sale in a Portuguese deli.
Jeffrey Greenberg/Universal Images Group via Getty Images
Jeffrey Greenberg/Universal Images Group via Getty Images

Processed meats are unhealthy because of their preservatives, high sodium, and cooking methods. Research Journal of Renal Nutrition determined the processed meat can harm kidneys. Participants who frequently consumed processed meats increased their chances of kidney disease by up to 99%.

Another study from the Journal of the American Society of Nephrology found that people with chronic kidney disease should avoid processed meats. If they don’t, they could develop end-stage renal disease (ESRD) that requires a kidney transplant. You can occasionally eat processed meats, but don’t rely on them.

The One Time You Should Switch To White Rice

A bowl of white rice sits on top of brown rice.
Roberto Machado Noa/LightRocket via Getty Images
Roberto Machado Noa/LightRocket via Getty Images

The difference between white rice and brown rice is similar to the distinction between white and wheat bread. Brown rice has more phosphorus and potassium than its lighter counterpart. One cup of brown rice contains 150 mg of phosphorus and 154 mg of potassium.

Patients with chronic kidney disease already have a risk of developing high potassium and high phosphorus. Eating brown rice sparingly should help. If you don’t want to resort to white rice, choose couscous, barley, bulgar, or buckwheat instead.

Go Beyond Bananas

A cyclist receives many bundles of bananas after winning the first stage of the Presidential Cycling Tour.
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Isa Terli/Anadolu Agency/Getty Images

Bananas are well-known for their high amount of potassium. But chronic kidney disease patients have a high risk of getting too much potassium in their blood, a condition called hyperkalemia. It is so serious that the American Kidney Fund called their education campaign about hyperkalemia “Beyond Bananas.”

One medium banana supplies 422 mg of potassium. That might be lower than other fruits, but it could worsen the kidneys over time. Around 20% of people with CKD have hyperkalemia and don’t even know it.

The Downside Of Oranges And Orange Juice

Oranges are paired with a glass of orange juice.
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Sneha Srivastava/IndiaPictures/Universal Images Group via Getty Images

Oranges are known for their high amounts of vitamin C, but they also supply a lot of potassium. One large orange provides 333 mg of potassium, and a glass of orange juice has 473 mg. If you have renal disease, Cleveland Clinic recommends that you limit the amount of orange and orange juice.

Other citrus juices, such as grapefruit and prune juice, also have a high amount of potassium. You can still eat citrus fruits in moderation if you have kidney issues.

Chocolate Can Help Or Harm Depending On The Type

Squares of chocolate are layered on top of each other.
Leon Neal/AFP via Getty Images
Leon Neal/AFP via Getty Images

Milk chocolate and white chocolate are not the best foods for kidneys. Harvard Health Publishing says that chocolate contains oxalate, which can contribute to kidney stones. If you have high blood sugar, adding extra fructose to your bloodstream will only make it worse.

On the other hand, studies say that raw cocoa powder can help kidneys. In January 2020, a study in Clinical Nutrition found that eating dark chocolate can aid patients with chronic kidney disease. Buy chocolate with a cocoa content above 70% for the benefits.

The Most Important Tip: Avoid Excess Salt

Salt pours off of a spoon.
Universal Images Group via Getty Images
Universal Images Group via Getty Images

Many people know that sodium increases blood pressure, but you may not know that it also worsens kidney health. According to the UK health group Action on Salt, several studies have linked salt to poor kidney health. High sodium increases the amount of protein in urine, which damages kidney tissue.

If you have renal disease, eating too much salt might accelerate the disease’s progression. High sodium can also increase the chances of developing kidney stones. It’s just bad all around.

Kidneys Do Not Appreciate Almonds

Almonds are carried in a white cloth.
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Michael Jacobs/Art in All of Us/Corbis via Getty Images

While almonds can help people combat heart disease, they do not do the same for the kidneys. Almonds contain a high amount of oxalates. Calcium oxalate can build up in the kidneys, forming stones or worsening the symptoms of kidney disease.

The American Journal of Medicine says that almonds also have a high bioavailability, which means that its oxalate is very active in the blood. These nuts are not the best choice for people with bad kidneys. Enjoy low-oxalate macadamia nuts instead.

Cashews Aren’t As Bad, But Don’t Go Overboard

A close-up shows cashew nuts.
Lane Turner/The Boston Globe via Getty Images
Lane Turner/The Boston Globe via Getty Images

Cashews have a lower amount of oxalate than other nuts. However, they still pose a risk for people with kidney disease. In 2017, a study in CMAJ found that eating cashews in high amounts can damage the kidneys in patients. People with hyperoxaluria, a high amount of oxalates, should definitely beware.

The researchers said that too much oxalate can cause renal disease nephrolithiasis or even kidney failure. If you eat a moderate amount of cashews, you should be safe.

All Canned Foods Carry Some Risk

A variety of canned foods are piled in a cardboard box.
Jerod Harris/Getty Images for Cost Plus
Jerod Harris/Getty Images for Cost Plus

While canned foods are convenient, they are not the most healthy choice. In 2013, a study in the journal Kidney International analyzed the chemicals that line food cans. Researchers concluded that some of these chemicals can harm your kidneys.

The worst culprit was bisphenol A (BPA), which bothers the lining inside of kidneys. Study author Howard Trachtman says that BPA in kidneys can cause problems elsewhere in the body. And that doesn’t even touch the high amount of sodium in canned foods!

Butter Contributes To Heart Disease And Kidney Failure

Butter is spread on bread.
Smith Collection/Gado/Getty Images
Smith Collection/Gado/Getty Images

You may have heard that butter is not healthy for the heart. But what does that have to do with the kidneys? As it turns out, a lot. Heart disease and kidney failure are closely related and often occur simultaneously, says the British Heart Foundation.

Both organs work with the blood. Around 63% of all fat in butter is saturated fat, and too much saturated fat can increase blood pressure. This places extra strain on both your kidneys and heart.

Sweet Potatoes Only Hurt If You Have A Kidney Disease

A woman eats sweet potato fries.
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If you had or currently have kidney issues, you may want to avoid sweet potatoes. Like regular potatoes, sweet potatoes contain a high amount of potassium, around 448 mg per cup. SF Gate says that sweet potatoes can aggravate kidney disease and prompt the formation of calcium-oxalate kidney stones.

If you don’t have kidney issues, you can eat sweet potatoes to prevent future ailments. Studies have found that sweet potatoes reduce sodium’s effect on the kidneys, explains Medical News Today.

Rhubarb: A Detriment To Kidney Patients

A man picks up sticks of rhubarb from a large pile.
SEBASTIEN BOZON/AFP via Getty Images
SEBASTIEN BOZON/AFP via Getty Images

Rhubarb is a vegetable that looks similar to celery; it also has one of the highest oxalate concentrations of any vegetable. For kidney disease patients, this is bad news. These patients already have a high amount of oxalate amount in the kidneys.

In 2012, a study in BMC Nephrology discovered that peoples’ oxalate levels directly increase after eating a lot of rhubarb. This could create kidney stones or a metabolic disorder called oxalosis. Patients with a history of renal disease may want to avoid rhubarb altogether.

Ignore Energy Drinks; Choose A Different Caffeine Source

A can of Monster energy drink sits on a table.
Roberto Machado Noa/LightRocket via Getty Images
Roberto Machado Noa/LightRocket via Getty Images

If coffee can be bad for kidneys, then energy drinks are coffee on steroids. In January 2020, a study in The Journal of Medical Case Reports concluded that energy drinks can cause “acute kidney injury.” They can also prompt hepatitis, or inflammation of the liver.

It’s not just the high caffeine. Energy drinks also contain an amino acid called taurine, which can contribute to chronic kidney disease, says the journal Nephrol Dial Transplant. Get your caffeine fix from elsewhere.

Apricots, Fresh Or Dried, Have Too Much Potassium

Apricots pour out of a bucket.
Klaus-Dietmar Gabbert/picture alliance via Getty Images
Klaus-Dietmar Gabbert/picture alliance via Getty Images

Apricots provide an excellent source of vitamin A, fiber, and potassium. But that’s too much potassium for a person with renal troubles. One cup of fresh apricots supplies 427 mg of potassium, which is far too much for those who suffer from hyperkalemia.

Even dried apricots are not safe. Registered dietitian Christine Gerbstadt says that eight pieces of dried apricots provide 325 mg of potassium. That much potassium can contribute to kidney stones and make symptoms worse for CKD patients.

Another Infection Can Come From Raw Shellfish

Raw uncooked prawns sit on a clay plate.
Natasha Breen/REDA&CO/Universal Images Group via Getty Images
Natasha Breen/REDA&CO/Universal Images Group via Getty Images

If you have kidney disease, steer clear from raw shellfish. Patients with bad kidneys are susceptible to a type of infection called vibrio vulnificus, which comes from eating raw fish. Research in the American Journal of Preventative Medicine found that renal disease patients are especially susceptible to vibrio vulnificus.

Sadly, three-fourths of the patients in the study were not told to avoid raw shellfish. The infection occurs in the kidney and can cause renal infection, according to the scientific journal Renal Failure.

People With Kidney Disease Should Not Eat High-Protein Diets

A vintage photo shows meat, eggs, milk, and butter.
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High-protein diets have many benefits, but they do not help people with renal diseases. Research in the American Journal of Kidney Diseases determined that high-protein diets can accelerate chronic kidney disease. The main culprits are animal proteins such as eggs, meat, and dairy.

High-protein diets also increase the risk of kidney stones. In 2002, a study in The BMJ determine that protein reduces the kidney’s ability to absorb calcium. Researchers saw a higher chance of kidney stones after just three weeks of a high-protein diet.