Plain carbonated water does not harden your arteries. No clinical evidence links the carbonation itself, the dissolved carbon dioxide that makes water fizzy, to arterial stiffness or calcification. The concern is understandable, though, because sugary carbonated drinks are strongly tied to cardiovascular problems. The difference comes down to what’s in the drink besides the bubbles.
What “Hardening” Actually Means
When doctors talk about hardened arteries, they usually mean atherosclerosis or arterial calcification. Calcium and fatty deposits build up inside artery walls, making them stiff and narrow. This reduces blood flow and raises the risk of heart attack and stroke. The standard way to measure this process is pulse wave velocity, which tracks how fast a pressure wave travels through your blood vessels. Stiffer arteries move the wave faster.
Researchers have measured pulse wave velocity in the context of carbonated water exposure and found no meaningful increase in arterial stiffness from carbonation alone. The limited lab data that exists simply doesn’t support the idea that CO2 bubbles do anything harmful to your vessel walls.
Sugary Soda Is the Real Problem
The studies that connect “carbonated beverages” to heart disease are almost always looking at sugar-sweetened sodas, not plain sparkling water. A large cross-sectional study of more than 22,000 adults found that people who drank five or more sugary sodas per week had 70% higher coronary artery calcium scores compared to non-drinkers, even after adjusting for diet, exercise, smoking, and other risk factors. Coronary artery calcium is a direct measure of the calcified plaque building up in the arteries that feed your heart.
The INTERSTROKE study, a major international case-control study, found that drinking more than two carbonated beverages per day was associated with 2.4 times the odds of ischemic stroke. Even one or fewer per day carried modestly elevated risk. But these findings reflect typical carbonated beverage consumption in the general population, which is overwhelmingly sugary soda, not sparkling water. The excess sugar drives weight gain, insulin resistance, chronic inflammation, and elevated blood lipids, all of which accelerate plaque formation in your arteries.
The Phosphoric Acid Factor in Colas
Cola-type sodas contain phosphoric acid, which adds a specific risk beyond sugar. High phosphoric acid intake disrupts the balance between calcium and phosphorus in your body. This imbalance can stimulate parathyroid hormone, pull calcium from bones, and interfere with vitamin D activation. The result is calcium ending up where it shouldn’t be, potentially including artery walls, while your bones get weaker. This mechanism has been studied primarily in the context of bone health and fracture risk, but the same mineral disruption is relevant to vascular calcification.
Plain sparkling water contains carbonic acid, not phosphoric acid. Carbonic acid is far weaker and breaks down quickly into water and carbon dioxide. It does not carry the same risks to your calcium-phosphorus balance.
What About Blood Pressure?
A 2024 systematic review looking at sparkling water and blood pressure found that current research focuses mostly on short-term nervous system responses right after drinking carbonated water, like a brief spike in blood pressure from the sensation of fizz. The review concluded that it remains unclear whether people with high blood pressure need to avoid sparkling water. No long-term evidence shows that plain carbonated water raises blood pressure enough to contribute to arterial damage over time.
One thing worth checking is the sodium content of your sparkling water. Most plain seltzers contain zero or negligible sodium, but some mineral waters, particularly European brands, can contain meaningful amounts. If you’re watching your sodium intake for blood pressure reasons, read the label.
Where Heart Health Organizations Stand
The American Heart Association lists sparkling water, seltzer, and club soda as recommended replacements for sugary drinks. Their “Sip Smarter” guidance explicitly suggests swapping full-calorie sodas, energy drinks, and sweetened teas for flat or sparkling water. There is no warning from any major cardiovascular organization about plain carbonated water and artery health.
The practical takeaway is straightforward. If you’re drinking plain sparkling water, the carbonation is not a cardiovascular concern. If you’re drinking multiple sugary sodas per day, the sugar and (in colas) the phosphoric acid are contributing to the exact kind of arterial damage you’re worried about. The bubbles are innocent bystanders.