Which sodas are bad for the kidneys? The Definitive Nutrition Diet Guide

October 27, 2025 •

3 min read

According to the National Kidney Foundation, regularly drinking soda can increase your risk of diabetes and high blood pressure, two leading risk factors for kidney disease. This guide explains which sodas are bad for the kidneys and offers actionable steps toward a kidney-friendlier nutrition diet.

Quick Summary

This article details why soda, including both regular and diet varieties, can negatively impact kidney function by examining harmful ingredients like phosphoric acid, high-fructose corn syrup, and artificial sweeteners. It also explores the risks of dehydration and offers healthier beverage alternatives.

Key Points

Dark-colored colas are especially bad for kidneys due to high levels of phosphoric acid, which can increase the risk of kidney stones and chronic disease.
High-fructose corn syrup in regular sodas promotes obesity, diabetes, and hypertension, all major risk factors for kidney damage.
Diet sodas are not a safe alternative; some studies link artificial sweeteners to faster kidney function decline.
Caffeine acts as a diuretic, potentially causing chronic dehydration that reduces blood flow to the kidneys.
The combination of additives like phosphorus and sugar forces kidneys to work harder, increasing overall strain.
Healthier alternatives include water, herbal teas, and fruit-infused sparkling water.
Zevia is a phosphate-additive-free soda alternative for those concerned about phosphorus intake.
Consulting a doctor or dietitian is recommended, especially for those with existing kidney conditions, to get personalized advice.

Understanding the Harmful Ingredients in Soda

Most sodas contain ingredients that can negatively impact kidney health, including high sugar content, artificial sweeteners, phosphoric acid, and caffeine. These ingredients can strain the kidneys, which are responsible for filtering waste.

The impact of phosphoric acid

Dark-colored colas, such as Coca-Cola and Pepsi, contain high levels of phosphoric acid, added for flavor and color preservation. High intake of phosphoric acid is linked to kidney damage and kidney stones. Unlike natural phosphorus, the additive form is easily absorbed, burdening the kidneys, especially for those with existing kidney issues.

The dangers of high-fructose corn syrup

Many regular sodas use high-fructose corn syrup (HFCS), which is linked to metabolic syndrome, obesity, and diabetes – major risk factors for chronic kidney disease (CKD). Fructose metabolism produces uric acid, which can damage kidneys and increase stone risk. Consuming two or more soft drinks daily has been associated with proteinuria, indicating kidney dysfunction.

The debate over diet sodas and artificial sweeteners

Diet sodas, despite being sugar-free, may still pose risks. Some studies suggest a link between artificially sweetened beverages and declining kidney function, though results are mixed. Artificial sweeteners like aspartame might stress the kidneys over time. One study noted that women drinking two or more diet sodas daily had a faster decline in kidney filtration rates. Dark-colored diet sodas can also contain phosphoric acid.

The dehydrating effect of soda

Caffeine, a common ingredient in many sodas, is a diuretic. While moderate consumption might not cause dehydration in healthy individuals, regular heavy intake can lead to chronic dehydration. Dehydration reduces blood flow to the kidneys, increasing their workload and the risk of kidney stone formation due to concentrated urine. Rehydrating with sugary drinks during dehydration can exacerbate the issue.

Healthier alternatives for a kidney-friendly diet

Limiting or avoiding sodas is important for kidney health. Consider these hydrating alternatives:

Water with natural infusions: Plain water is optimal. Add lemon, cucumber, or mint for flavor.
Herbal teas: Unsweetened green or herbal teas are low-sugar options.
Flavored sparkling water: Provides fizziness without harmful additives. Some brands like Zevia are phosphate additive-free.
Diluted fruit juice: Unsweetened juice diluted with water can reduce sugar intake.
Homemade smoothies: A nutritious option, but be mindful of potassium and sugar content if you have kidney disease.

Comparison of common soda ingredients and their kidney impact


Ingredient	Found in (Example)	Impact on Kidneys
Phosphoric Acid	Dark-colored colas (Regular & Diet)	Increases risk of kidney stones and chronic kidney disease by creating an acidic environment and adding phosphorus overload.
High-Fructose Corn Syrup	Regular sodas	Increases risk of diabetes, hypertension, and obesity, which are all risk factors for kidney disease. Metabolizes into uric acid, which can damage kidneys.
Artificial Sweeteners	Diet sodas	Observational studies suggest a link to a faster decline in kidney function, though the mechanisms are still under investigation.
Caffeine	Most colas, diet sodas	Acts as a diuretic, potentially leading to dehydration and reduced blood flow to the kidneys, especially with frequent consumption.

Conclusion: Making smarter choices for your kidneys

To protect kidney health, it's best to avoid or limit all types of soda. Ingredients like high-fructose corn syrup, phosphoric acid, artificial sweeteners, and caffeine can strain the kidneys, increase stone risk, and accelerate CKD progression. Choosing healthier options like water, herbal tea, or naturally flavored sparkling water supports long-term renal function. Understanding these risks helps you make informed decisions for a healthier diet and better well-being.

What are some healthier drink alternatives to soda? Here are a few options:

Naturally flavored water with cucumber, mint, or lemon slices.
Unsweetened green or herbal tea.
Flavored sparkling water, especially brands with no phosphate additives like Zevia.
Small amounts of diluted, unsweetened fruit juice.
Homemade smoothies with kidney-friendly fruits.
Plain water, which is the best choice for flushing toxins from the body.
Coconut water occasionally, especially if you have no issues with potassium levels.

Frequently Asked Questions

While it lacks sugar, research has linked high consumption of diet soda (two or more servings per day) with a faster decline in kidney function in some populations. Some diet sodas also contain phosphoric acid, a known risk factor.

Phosphoric acid, found especially in dark colas, adds an unnaturally high level of phosphorus to the body. This is absorbed more readily than natural phosphorus and places extra strain on the kidneys, potentially contributing to bone issues and kidney stones.

Yes, high intake of soda, particularly sugary and dark-colored varieties, has been linked to an increased risk of kidney stones. The high fructose and phosphoric acid content contribute to imbalances that promote stone formation.

Clear sodas like Sprite and 7Up are better than dark colas because they generally lack phosphoric acid. However, they still contain high sugar or artificial sweeteners, so they should be consumed in moderation or avoided.

High-fructose corn syrup increases the risk of obesity, diabetes, and hypertension, all of which are damaging to kidneys. Its metabolism also raises uric acid levels, which can lead to kidney stones and kidney scarring.

Not necessarily. Carbonated water (like seltzer) without added sugar or phosphoric acid is generally considered safe for the kidneys. However, sparkling waters with artificial flavors or additives should still be checked for ingredients that could pose a risk.

The best drink for kidney health is plain water. Proper hydration helps the kidneys effectively flush out toxins and waste products. For flavor variety, you can add natural infusions like lemon or cucumber.