If you’ve ever had a kidney stone, you know how painful they can be. Most people who have had one kidney stone would like to avoid getting another one. One thing that may help is considering what you eat. Certain foods can increase the risk of kidney stones, while others decrease it. You may get a kidney stone diet chart or directions from your doctor, but not all patients receive information about how to change their diet to prevent future kidney stones.
Is there a diet for kidney stone prevention? What are the best foods to avoid kidney stones?
Can food cause kidney stones?
Ultimately, kidney stones (also known as renal calculi) form when minerals in the urine crystallize inside of the kidney. The symptoms of the kidney stone occur as it passes down the ureter (the tube that connects the kidney to the bladder). The minerals in your blood ultimately come from the food that you eat, and this is why changing your diet can have an impact on your risk of kidney stones.
Not all kidney stones are the same, and there are different foods that help to prevent kidney stones for each type. The most common type of kidney stone is a calcium stone, which may be made of calcium oxalate or calcium phosphate. The next most common is a uric acid stone.
What’s the best diet to prevent kidney stones?
The types of foods that help prevent kidney stones, or that make them more likely to form, are different for different types of stones. The calcium oxalate renal calculi diet will be somewhat different from the calcium phosphate kidney stone diet, or the uric acid renal calculi diet. Some dietary approaches work for all types of stones, while others are only effective for some of the types.
Some kidney stones can pass into the bladder and then grow into bladder stones. There are also other causes of bladder stones; if you’ve had a bladder stone, diet may help if your bladder stone originated as a kidney stone.
Can dairy cause kidney stones?
Because the most common type of kidney stone contains calcium, it’s a common misconception that dairy in the diet would lead to kidney stones. Since dairy products contain a high level of calcium, many people assume that they need to decrease their consumption of dairy in order to prevent another stone.
However, eating calcium is actually not what causes calcium-based kidney stones. In fact, lowering the calcium in your diet can paradoxically increase your risk of developing kidney stones. This is because when you eat calcium, it binds to other stone-causing substances like oxalates, and blocks them from causing stones. Making sure that you get enough calcium in your diet may actually decrease your risk of kidney stones.
Can ice cream cause kidney stones?
As with other types of dairy, people worry about the calcium in ice cream, but there’s no reason to be concerned about this. However, the sugar in ice cream could potentially be an issue. Fructose, which is found at high levels in both high fructose corn syrup (HFCS) and sucrose (table sugar), increases urinary calcium excretion as well as uric acid excretion, so it increases the risk of both calcium and uric acid stones.
Sugar also decreases your urine volume, which also increases the risk of all types of kidney stones. Reducing your consumption of sweets, including ice cream, helps to decrease your risk of kidney stones.
Protein and kidney stones
Eating large amounts of animal protein creates a higher risk for both calcium and uric acid stones. When you eat red meat, poultry, and some fish and shellfish, this leads to increases in the level of uric acid in your urine. Uric acid can form kidney stones, and the acid also increases the amount of calcium that goes into your urine, creating an increased risk for calcium oxalate and calcium phosphate stones as well.
Plant proteins generally don’t cause this issue, because the balance of the amino acids that they contain is different. Focusing on including plant sources of protein in your diet, such as tofu, tempeh, and beans, can help to meet your body’s protein needs while reducing your risk of kidney stones. Eggs and salmon are also two animal protein sources that produce low levels of uric acid, so these are also good choices if you’re trying to avoid kidney stones.
It should be noted that not all studies have confirmed that high levels of animal protein in the diet increase the risk of kidney stones, so this issue is not entirely settled scientifically. Still, based on the evidence that we have, most doctors recommend decreasing the intake of animal protein in order to decrease the risk of kidney stones.
Vegetables and kidney stones
The excretion of calcium in the urine is also affected by the balance of other minerals in the body. Higher levels of sodium and lower levels of potassium in the diet are both linked to increased excretion of calcium in the urine, which then raises the risk of kidney stones. Lowering sodium intake and raising potassium intake will decrease the risk of kidney stones.
Vegetables and fruits are an excellent source of potassium, and are a good type of food to avoid kidney stones. Some of the best sources are dark green leafy vegetables, avocados, and bananas, although many other types of produce also provide potassium. Ensuring that you get enough potassium through these foods every day will help to prevent kidney stones.
Nuts that cause kidney stones
Certain types of nuts, including almonds and cashews, contain high levels of oxalates, which can form calcium oxalate kidney stones. However, it’s actually not necessary to cut these foods out of your diet; instead, try to pair them with dietary calcium sources (like dairy). This way, the calcium in the dairy will bind to the oxalates in the nuts inside of your gut, and block them from later forming stones in the kidneys.
A similar technique can be used with vegetables that contain high levels of oxalates, like leafy green vegetables and rhubarb. Pairing them with dairy products can help to prevent the oxalates from turning into kidney stones. These vegetables contain other beneficial compounds (like potassium), so rather than cutting them out of your diet, you could try pairing them with dairy products.
Drinks to avoid with kidney stones
One common condition that can increase the risk of kidney stones is dehydration. When you’re dehydrated, your kidneys will keep fluid in your body, instead of pulling it out into the urine. Because of this, the urine becomes more concentrated. In a more concentrated solution, minerals are more likely to crystallize. This is why drinking a lot of fluid is crucial for people who are trying to avoid kidney stones. In fact, staying well-hydrated is one of the most important diet changes for kidney stones.
Studies have shown that drinking soda significantly increases the risk of kidney stone formation. This is especially true of sodas that contain phosphoric acid, which is often added to give the soda an acidic “bite” that balances out the sweetness. If you’re worried about kidney stones, it’s best to avoid soda as much as possible.
Although both tea and coffee do contain oxalates, studies have actually shown that these beverages actually decrease the risk of kidney stones. It’s not yet certain why this is the case, but if you’re a lover of a hot caffeinated beverage in the morning, there’s no reason why you need to stop drinking it.
When you drink a lot of alcohol, your body becomes dehydrated. This can increase the risk for kidney stones. However, when consumed in moderation, alcohol doesn’t seem to be associated with kidney stones. Limit your consumption to one to two drinks in a day.
Ensuring that your kidney stones haven’t caused kidney damage
Most of the time, kidney stones don’t cause any long-term problems. However, if a kidney stone blocks the ureter for too long, pressure can build up inside the kidney, causing damage. In order to be sure that this hasn’t happened, a kidney function test is helpful. Using a blood test and/or a urine test, you can see how well your kidneys are working, and can detect kidney disease while it’s still in an early stage and is more treatable.
To get your kidney function tested, you can visit your doctor and ask them to order lab tests, then go to a laboratory to have samples drawn. Another option is to order a home test kit, which allows you to take the samples yourself at your convenience. These options differ in the way that the samples are taken, but the samples are sent to the same laboratories for testing, so the tests are basically the same. The home testing option is just more convenient for many people.
Sources
Eating, Diet & Nutrition for Kidney Stones. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-stones/eating-diet-nutrition. Accessed 29 June 2022.
Ferraro PM, Bargagli M, et al. Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian-Vegan Diets. Nutrients. 2020 Mar 15;12(3):779. doi: 10.3390/nu12030779.
Kidney Stone Diet Plan and Prevention. National Kidney Foundation. https://www.kidney.org/atoz/content/diet. Accessed 29 June 2022.
Siener R. Nutrition and Kidney Stone Disease. Nutrients. 2021 Jun 3;13(6):1917. doi: 10.3390/nu13061917.
