LaCroix is not bad for your kidneys. It contains no sugar, no sodium, and only trace amounts of the compounds that make regular soda a concern for kidney health. In fact, the National Kidney Foundation lists unsweetened sparkling water among the best fluids for preventing kidney stones.
Why Soda Harms Kidneys but Sparkling Water Doesn’t
The kidney concerns around carbonated drinks come almost entirely from regular soda and diet soda, not from plain sparkling water. The key culprit is phosphoric acid, which is found in high concentrations in colas and other dark sodas. Some colas contain up to 400 mg of phosphoric acid per 12-ounce serving. At those levels, phosphoric acid is linked to lower bone density and places extra filtering demands on the kidneys.
A 12-ounce can of LaCroix contains roughly 5 mg of phosphoric acid. That’s about 1% of what you’d get from a cola. At that level, phosphoric acid is not a meaningful concern for kidney function. The carbonation itself, which is simply dissolved carbon dioxide, does not damage kidney tissue or interfere with how your kidneys filter waste.
Kidney Stones and Sparkling Water
If you’re prone to kidney stones, staying hydrated is one of the most effective things you can do to prevent them. More fluid means more dilute urine, which makes it harder for calcium and oxalate crystals to clump together and form stones. The National Kidney Foundation specifically includes unsweetened sparkling water on its list of recommended beverages for stone prevention, alongside plain water, milk, and unsweetened coffee or tea.
Small studies on sparkling mineral water (a slightly different product that contains dissolved minerals like calcium, magnesium, and bicarbonate) have looked at whether it changes the urine chemistry that leads to stones. In one study of 10 people without a history of stones, urinary citrate dropped slightly from 2.5 to 2.2 mmol per day. That matters because citrate helps prevent stones from forming. But in a follow-up study of 10 people who did have a history of kidney stones, citrate levels actually rose. The results were mixed enough that researchers couldn’t draw a firm conclusion either way, and these studies used mineral water with a specific mineral profile, not a product like LaCroix that contains essentially no minerals.
Sodium, Sugar, and Kidney Stress
Two of the biggest dietary drivers of kidney problems are excess sodium and excess sugar. High sodium intake forces your kidneys to retain more water and raises blood pressure, which over time damages the small blood vessels in the kidneys. High sugar intake contributes to diabetes, which is the leading cause of chronic kidney disease.
LaCroix contains zero sodium and zero sugar. This is a meaningful advantage over most other flavored beverages. Even flavored waters and sports drinks often contain added sodium or sweeteners. If you’re replacing sugary drinks or soda with LaCroix, your kidneys are getting a better deal.
Hydration Matters More Than the Bubbles
Sparkling water hydrates your body just as effectively as flat water. Research confirms that carbonated water counts toward your total daily fluid intake without any meaningful difference in how well your body absorbs it. As Dr. Colleen Muñoz, director of the Hydration Health Center at the University of Hartford, has noted, sparkling water “seems to be good for you in terms of total fluid intake,” particularly for people who find plain water unappealing and would otherwise drink less throughout the day.
This is especially relevant for kidney health. Chronic mild dehydration makes your kidneys work harder to concentrate urine and filter waste. Over time, it increases your risk of kidney stones and can contribute to urinary tract infections. If sparkling water helps you drink more fluid overall, it’s actively supporting your kidney function rather than threatening it.
What About the Natural Flavors?
LaCroix’s ingredient list is short: carbonated water and natural flavors. The natural flavors are derived from fruit essences and oils, and they’re present in extremely small quantities. There are no artificial sweeteners, no potassium additives, and no preservatives that would place additional filtering burden on your kidneys. For people with advanced kidney disease who need to limit potassium or phosphorus intake, LaCroix is far safer than fruit juice, milk, or many other common beverages.
The only scenario where any sparkling water could be a minor concern is if the carbonation causes you to feel full and drink less total fluid as a result. Some people find that the bubbles make them feel bloated, which can reduce how much they drink in a sitting. If that happens to you, alternating between sparkling and still water is a simple fix.