Zero sugar drinks, such as diet sodas and artificially sweetened beverages, are popular alternatives to sugar-sweetened beverages. Kidney stones are hard deposits of minerals and salts that form inside the kidneys, causing pain and frequent health issues. Zero sugar drinks are often consumed as a healthier alternative to sugar-sweetened beverages. While the ingredients are generally recognized as safe, their chemical properties and consumption habits warrant a closer look at their potential effects on kidney health.
How Kidney Stones Form
Kidney stones develop when urine becomes overly concentrated with crystal-forming substances, such as calcium, oxalate, and uric acid. These minerals and salts then crystallize and aggregate into solid masses within the urinary tract. The most common type of stone is calcium oxalate, which accounts for the majority of cases.
The concentration of these substances is influenced by several factors, including diet, genetics, and overall fluid intake. Hydration plays the most significant part in prevention because sufficient fluid volume dilutes the urine, making it less likely for crystals to form. Conversely, low urine volume, often a result of dehydration, creates a supersaturated environment where stone formation is favorable. A shift in urine pH is also a factor, as certain stone types form more readily at specific pH levels.
Ingredients in Zero Sugar Drinks That Affect Kidney Health
Some components found in zero sugar drinks possess properties that could alter the body’s mineral balance and urine chemistry. One ingredient of concern is phosphoric acid, used to provide the sharp, tangy flavor in many dark cola beverages. High intake of this acid can increase the amount of calcium and phosphate excreted in the urine. This elevated urinary calcium concentration may increase the risk for calcium stone formation, particularly calcium phosphate stones.
Citric acid is another common additive, often used in clear sodas and flavored waters. Unlike phosphoric acid, the citrate form of citric acid is protective because it binds to calcium in the urine, making it unavailable to form stones. However, the high acidity of these drinks can create an acidic environment, which may increase the risk for uric acid stones in susceptible individuals. The non-nutritive sweeteners themselves are not directly linked to stone formation through a chemical mechanism.
Current Research on Zero Sugar Drinks and Kidney Stone Risk
Large-scale studies have explored the association between various beverages and stone incidence. Research found that the consumption of sugar-sweetened sodas was associated with a significantly higher risk of developing kidney stones. This is attributed to the high fructose content, which can increase the excretion of stone-forming substances like oxalate and uric acid.
Consumption of artificially sweetened non-cola beverages was found to have only a marginally higher risk of stone formation compared to the lowest consumers. Artificially sweetened colas were associated with a trend toward a reduced risk compared to sugar-sweetened versions. This suggests that replacing sugary drinks with zero sugar alternatives reduces the risk associated with high sugar intake. However, drinking any beverage other than water may displace the consumption of water, which is the optimal fluid for stone prevention.
The risk from zero sugar drinks is lower than from their sugar-sweetened counterparts, but they may not be entirely without risk. Some studies suggest an 11% higher stone risk with daily consumption of artificially sweetened beverages. The primary concern for frequent consumers of zero sugar dark colas remains the presence of phosphoric acid, which can disrupt calcium balance. For many people, the most significant risk factor is inadequate overall fluid intake when these drinks replace plain water.
Hydration Alternatives for Kidney Stone Prevention
The most effective preventive measure is consistently high fluid intake to ensure sufficient urine dilution. Medical experts often advise people with a history of stones to drink enough fluid to produce at least 2 liters of urine daily, which typically requires drinking between eight to ten 8-ounce glasses of water. The goal is to maintain urine that is pale yellow or nearly clear throughout the day.
Beyond plain water, several beverages are recommended for their stone-inhibiting properties. Natural lemonade or lemon water contains high levels of citrate, which helps prevent calcium from crystallizing and can even break up small stones. Orange juice is also high in citrate and appears beneficial for lowering stone risk. Coffee and tea, both caffeinated and decaffeinated, have also been associated with a lower incidence of kidney stones. Limiting highly acidic zero sugar drinks, especially dark colas, and prioritizing water and naturally citrated drinks is a practical approach to prevention.