Plain sparkling water is significantly healthier than regular soda. A 12-ounce can of cola contains around 39 grams of added sugar and 140 calories, while unsweetened sparkling water has zero of both. That alone accounts for most of the health gap between the two drinks, but the differences go well beyond sugar and calories.
Sugar Is the Biggest Difference
The World Health Organization recommends keeping added sugar below 10% of your total daily calories, with additional benefits if you stay under 5%. For someone eating 2,000 calories a day, that 5% target works out to about 25 grams. A single can of regular soda blows past that limit. Drink one a day, and you’re adding roughly 50 pounds of sugar to your diet per year.
That sugar load drives weight gain, raises the risk of type 2 diabetes, and contributes to heart disease. Sparkling water sidesteps all of this. The carbonation gives you the fizzy sensation without any of the metabolic cost.
What About Diet Soda?
Diet soda eliminates the sugar but introduces artificial sweeteners. The most common ones are aspartame (roughly 200 times sweeter than table sugar), sucralose (600 times sweeter), acesulfame potassium, and stevia. The FDA considers all of these safe within established daily limits, though the WHO has recommended limiting their use.
A 2023 study raised concerns about sucralose specifically, finding that a compound formed when the body metabolizes it (sucralose-6-acetate) caused DNA damage in lab testing. The long-term significance of this in humans isn’t fully settled, but it illustrates why diet soda isn’t simply “soda minus the downsides.” Plain sparkling water avoids artificial sweeteners entirely, which makes it the cleaner choice even compared to zero-calorie sodas.
Hydration Is Essentially Equal to Still Water
One common worry is that carbonation somehow makes water less hydrating. It doesn’t. A study using the beverage hydration index, which measures how much urine your body produces after drinking specific beverages, found that sparkling water performed identically to still water. If you prefer bubbles and it helps you drink more fluids throughout the day, that’s a net positive.
Tooth Enamel: Flavor Matters More Than Fizz
Carbonation does make water slightly more acidic than flat water, which has led to concerns about enamel erosion. But according to American Dental Association research, plain sparkling water and regular water had about the same effect on tooth enamel in lab testing. The carbonation alone isn’t the problem.
Citrus-flavored sparkling waters are a different story. The added citric acid raises acidity levels enough to increase the risk of enamel damage over time. Regular soda is worse still, combining high acidity with sugar that feeds the bacteria responsible for cavities. If you’re choosing between a lemon-lime soda and plain seltzer, the seltzer is far gentler on your teeth. But if you drink a lot of citrus-flavored sparkling water, consider rinsing with plain water afterward.
Bone Health and Phosphoric Acid
There’s a persistent belief that carbonated drinks weaken bones. The evidence points to cola specifically, not carbonation in general. A large study found that non-cola carbonated drinks had no association with lower bone mineral density, while cola intake was linked to lower bone density at the hip in women. Harvard Health reports that seltzer water does not appear to contribute to osteoporosis or increase fracture risk.
The likely culprits in cola are phosphoric acid and caffeine, not the bubbles. Phosphoric acid gives dark colas their sharp bite and acts as a preservative. The body absorbs this added phosphorus more readily than the phosphorus found naturally in food. There’s also a displacement effect: people who drink a lot of soda tend to drink less milk and other calcium-rich beverages, which may matter more for bone health than any direct chemical effect.
Kidney Stone Risk
Sugar-sweetened sodas, particularly those containing phosphoric acid, are associated with a higher risk of kidney stones. A 2021 review found that phosphoric acid changes the metabolites your body excretes in urine in ways that promote stone formation. People with recurring kidney stones faced significantly higher risk when consuming these drinks regularly. Even diet soda, which still contains phosphoric acid and caffeine, may carry some of this risk. Plain sparkling water contains neither ingredient.
One Surprising Caveat: Carbonation and Hunger
There is one area where sparkling water isn’t clearly superior. A study reported by UCLA Health found that men who drank carbonated water, whether sweetened or unsweetened, had triple the blood levels of ghrelin (the hormone that signals hunger) compared to those who drank flat water. The researchers attributed this to the carbon dioxide itself, not any added ingredients. This was a small study of 20 men, so it’s not definitive, but it suggests that carbonation of any kind could make you feel hungrier. If you’re trying to manage your appetite, this is worth keeping in mind.
Flavored Sparkling Water Needs a Label Check
Not all sparkling water is created equal. Some flavored varieties contain added sugars, artificial sweeteners, phosphoric acid, or sodium. A flavored sparkling water with sucralose and phosphoric acid is closer to diet soda than it is to plain seltzer. Ohio State University’s nutrition guidance recommends choosing sparkling water without added artificial sweeteners if you’re trying to move away from soda. Reading the ingredient list matters: if it lists only carbonated water and natural flavors, you’re in good shape. If the label starts to look like a chemistry set, you’re drinking something closer to soda in disguise.
The simplest option is making sparkling water at home with a carbonation device, which guarantees you’re getting nothing but water and carbon dioxide.