La Croix hydrates you just as well as plain water. Sparkling water and still water produce the same amount of urine over four hours, meaning your body retains the same volume of fluid from both. The carbonation in La Croix doesn’t interfere with absorption, and the drink contains no sugar, caffeine, or other ingredients that would change its hydrating properties.
Sparkling Water Scores the Same as Still Water
A clinical trial published in the American Journal of Clinical Nutrition tested 13 common beverages to create a “beverage hydration index,” measuring how much fluid the body retained two hours after drinking each one compared to plain water. Sparkling water performed identically to still water. Cumulative urine output at four hours was no different between the two, which means carbonation doesn’t cause your body to flush out extra fluid.
The CDC groups sparkling water with plain tap water and unsweetened bottled water as recommended alternatives to sugary drinks. There’s no separate guideline or limit for sparkling water. If you prefer the fizz, it counts toward your daily fluid intake the same way a glass of tap water would.
How Carbonation Moves Through Your Body
One concern people have is whether the bubbles in carbonated water slow down absorption in the gut. A study on gastric emptying found that carbonated water did not change the overall rate at which the stomach empties liquid into the small intestine, where absorption happens. The carbonation did shift where food and liquid sat inside the stomach (more stayed in the upper portion temporarily), but the total emptying time was identical to still water.
In practical terms, La Croix reaches your bloodstream at the same speed as flat water. You won’t notice a difference in how quickly you feel rehydrated.
What’s Actually in La Croix
La Croix contains two ingredients: carbonated water and “natural flavor.” Those natural flavors are volatile plant compounds extracted from fruits and botanicals. Limonene, for instance, is an oil naturally found in citrus peels that gives citrus-flavored varieties their scent. Linalool, another common flavoring compound, occurs naturally in flowers and spice plants. These are aromatic compounds used in tiny amounts, not sweeteners or acids.
This matters for hydration because the drink contains no phosphoric acid (found in colas), no sugar, no caffeine, and no sodium. Phosphoric acid and sugar are the ingredients in other carbonated beverages that raise concerns about bone health and kidney stones. Without them, La Croix behaves like water with bubbles and a hint of scent.
Carbonation, Appetite, and One Small Caveat
There is one secondary effect worth knowing about. A study found that carbonated beverages increased levels of ghrelin, the hormone that signals hunger, in both rats and a group of 20 healthy men. Higher ghrelin levels led to increased food consumption in the animal portion of the study. This doesn’t affect hydration, but if you’re drinking La Croix throughout the day and noticing increased snacking, the carbonation itself could be playing a role.
No Evidence of Bone or Kidney Harm
A common worry about any carbonated drink is its effect on bones. Research has consistently separated cola from other sparkling beverages on this point. A large study found that cola intake was associated with lower bone mineral density at the hip in women, but non-cola carbonated drinks showed no such association. A separate clinical trial had postmenopausal women drink about a quart of carbonated mineral water daily for eight weeks. Blood and urine markers for bone turnover were identical to those of women drinking the same amount of still water.
On kidney stones, the risk factors are sugar and phosphoric acid. Sugar-sweetened sodas are associated with higher kidney stone incidence because fructose increases urinary excretion of calcium, oxalate, and uric acid. Non-cola carbonated beverages actually contain citric acid, which may increase urinary citrate and reduce stone risk. La Croix, with no sugar and no phosphoric acid, doesn’t carry these concerns.
When Sparkling Water Might Not Be Ideal
During intense exercise or heavy sweating, the issue isn’t carbonation but electrolytes. La Croix doesn’t contain sodium or potassium, so it replaces fluid but not the minerals you lose through sweat. For everyday hydration (sitting at a desk, light activity, meals), it works perfectly. For long runs or hot outdoor work, you’d want to pair it with electrolyte sources just as you would with plain water.
Some people also find that carbonation causes bloating or discomfort, which can make it harder to drink enough volume at one time. If the fizz makes you stop drinking sooner than you would with flat water, you may end up taking in less total fluid. The water itself hydrates identically, but comfort affects how much you actually consume.