Does Soda Cause Kidney Stones?

Is this true? Can drinking soda cause kidney stones? Are dark sodas worse than others?

Unfortunately, yes. Drinks that are sweetened with sugar, such as soda, are associated with an increased risk of kidney stones. Diet cola may also cause stone formation. However, non-cola diet soda may have some beneficial ingredients.

Read on to learn about the nutrition of soda, explore the differences between regular and diet varieties, and understand healthier alternatives you should drink to prevent kidney stones from forming.

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Nutrition in Soda

First, lets take a look at what is actually in soda.

Of course, nutrition varies between types of soda. Generally regular soda contains more sugar (usually in the form of fructose) than diet soda. Cola (regular or diet) also contains phosphoric acid which may increase stone formation. Conversely, diet sodas are sweetened with a variety of artificial sweeteners such as aspartame, acesulfame k, Splenda or Stevia.

In general, most soda also lacks beneficial nutrients such as protein, vitamins and minerals.

Does Soda Cause Kidney Stones?

In short, yes. Soda can cause kidney stones. People who drink at least one sugar-sweetened soda per day have a 23-33% increased risk of kidney stones. (1)

Let’s dive into why that might be.

Sugar in Soda

Most sodas are sweetened with fructose, a type of sugar that has been associated with kidney stones. Fructose can increase urinary calcium, oxalate and uric acid. As research has shown, high levels of these substances in urine can cause kidney stones. (2)

Sugar in other beverages can cause kidney stones too. Punch, sweet tea, lemonade, and some fruit juices have been associated with kidney stones. (1) (3)

It is important to know that fructose in fruit does not cause kidney stones. In fact, people who eat more fruit (and veggies!) are much less likely to have kidney stones. (4) (5) Reason being, the amount of fructose in fruit is significantly less than in soda. Not only that, fruit also has many other beneficial components such as fiber, potassium and other vitamins and minerals.

Phosphoric Acid in Soda

Cola, specifically, has a lot of phosphoric acid in it which may be why soda can cause kidney stones. Non-Cola sodas usually do not have phosphoric acid.

Some studies have shown a higher risk of kidney stones, and harmful changes in urine in people who drink cola (6) (7) (8). However, others have shown a modest reduced risk. (1)

Some articles have suggested that phosphoric acid dissolves kidney stones. This is not true. In fact, there is no food or supplement that can dissolve kidney stones. However, nutrition can play an big role in prevention!

Bottom Line: Because phosphoric acid is harmful for people with kidney disease, this indicates it generally is not good for kidneys. I would steer clear of dark sodas for kidney stone prevention.

Does Diet Soda Cause Kidney Stones?

Diet Cola

Although diet cola doesn’t have sugar in it, it does have phosphoric acid. This may increase kidney stones.

Diet Non-Cola Sodas

Diet sodas, other than cola, usually do not have phosphoric acid in them.

Examples of diet non-cola sodas:

• Diet 7-Up
• Diet Squirt
• Diet Sunkist Orange
• Sierra Mist Zero
• Diet Canada Dry

Diet non-cola soda is usually sweetened with ingredients that contain citrate, such as potassium citrate. They also often contain citric acid itself. Dark sodas like Coke, Pepsi, root beer or Dr. Pepper have much less citrate in them. (9)

Citrate can help prevent kidney stones for some people. In fact, low levels of urine citrate is a common cause of kidney stones. (10) You may have been prescribed potassium citrate, which is a medication commonly used to prevent kidney stones.

If you do have low urine citrate, making sure to eat plenty of fruits and vegetables and avoid too much protein is the best way to increase urine citrate.

Despite relatively high citrate, research has not consistently shown a reduced risk of kidney stones with non-cola diet soda. (1) This may be because the amount of citrate in non-cola diet soda is not enough to make a difference for kidney stone prevention.

However, non-cola diet sodas do not increase kidney stone risk like regular soda.

What To Drink To Prevent Kidney Stones

Drinking (a lot!) of fluid is key to preventing kidney stones. It is the #1 thing you can do for kidney stone prevention. The American Urological Association recommends drinking enough to make at least 2 1/2 liters of urine every day. (11) I recommend aiming for 3 liters of fluid per day for most people.

So, what should you drink?

Water

Unsurprisingly, plain old water is the best choice for kidney stone prevention. Most of your fluid should come from water.

Getting in this much water is no easy task! Many of my patients love using a smart water bottle, such as the Hidrate Spark*. This water bottle tracks how much water you drink, and even reminds you to drink if you fall behind!

Unsweetened Carbonated Water

This is one food trend I can get behind! I love unsweetened sparkling waters like La Croix*, Spindrift* and Bubly*.

These drinks have zero sugar and are a wonderful way to mix up your fluids and make water a little less mundane.

Probiotic Sodas

A healthier version of soda? Drinks like Olipop* and Poppi* offer the flavorful taste of soda without the added sugar! 

These drinks have zero phosphoric acid, only 2-5 grams of sugar (varies based on the flavor) and are packed with fiber, probiotics, and natural sweeteners!

Milk

Getting enough calcium is very important for people who have calcium kidney stones. Milk is a wonderful calcium source, and counts toward your fluid goal

Coffee & Tea

Despite concerns over oxalate, people who drink coffee and tea are less likely to have kidney stones. (1)

Yes, even tea! Tea does have oxalate in it. However, there is no research to show a low oxalate diet prevents kidney stones.

Crystal Light Lemonade

Crystal Light Lemonade* contains a very high amount of citrate. Much more than diet sodas.

If you have low urine citrate, Crystal Light Lemonade* may help increase it to the normal range. Don’t forget! Eating more fruits and vegetables can also increase urine citrate.

Small Amounts of Non-Cola Diet Soda

Drinking non-cola diet soda is a great way to mix it up and help meet your fluid goals!

I usually recommend no more than 1 can of non-cola diet soda per day. There is some research that diet soda, in large amounts, is associated with some chronic diseases.

Does Soda Cause Kidney Stones? The Verdict

Any kind of sugar sweetened drink, including soda, can cause kidney stones. Unfortunately, diet cola may also cause kidney stones.

However, non-cola diet sodas may have some beneficial ingredients for kidney stones. These sodas can be consumed in moderation for people who have kidney stones. As always, most of your fluid should be water. Learn more about nutrition and kidney stone prevention here!

Feel like you would benefit from additional support? Through our personalized 1:1 services with a Registered Dietitian and Kidney Stone Nutrition School, we help people prevent kidney stones and feel confident in their dietary choices.

Have you struggled with kidney stones in the past? Share your experience in the comment section below and we’ll get back to you ASAP!

Happy Eating!

Melanie