Carbonated soft drinks have got a lot of bad press. From their high sugar content to their high artificial sweetener content, from their acidity to their health dangers, it seems sodas are out. And thatâ€™s without mentioning the popular urban myth that a tooth left in cola overnight will dissolve completely away!
But carbonated water shouldnâ€™t suffer from those same problems, should it? After all its only difference from water is that itâ€™s carbonated. Thatâ€™s just bubbles, so is carbonated water bad for you?
It may come as a surprise, but the acidity of soft drinks is largely due to their carbonation. The fizz is carbon dioxide, which is no problem as a gas, itâ€™s the same gas you breathe out. But when itâ€™s dissolved in water it becomes carbonic acid, and itâ€™s moderately corrosive. Carbonated water can have a pH as low as 3, just from the carbonation!
To put that in perspective, pH is a logorhythmic scale, meaning that each step makes a powerâ€™s worth of difference: pH 4 is ten times more acidic than pH5 (7 is neutral). So itâ€™s pretty acidic â€“ about as acidic as orange juice, but still less acidic than lemon juice.
That means itâ€™s not a great idea to leave your teeth in contact with carbonated water for too long. In 2007, Dr. David Bartlett, who specialized in prosthodistry (false teeth) at Londonâ€™s Kingâ€™s College, published a piece in The Journal of the American Dental Association in which he claimed that brushing the teeth with a mildly abrasive tooth powder would take about 100 years to erode away the top 1 mm of tooth enamel. But he claimed that he had seen this degree of tooth damage in only two years in patients who heavily consumed carbonated beverages on a regular basis.
But unlike sodas, when you drink carbonated water, itâ€™s gone in seconds: the problem with sodas is really their sugar content. This causes a film of sugar to cling to the teeth, where bacteria in the mouth eat it and excrete acids including carbonic acid. Itâ€™s these acids that rot the enamel of your teeth, not the carbonic acid caused by the drink being carbonated!
In fact, in studies designed to find the difference in between sparkling and still water in terms of their effects on teeth, there was found to be no difference at all. Neither still nor sparkling water is harmful to teeth.
Then thereâ€™s the suggestion that carbonated beverages can cause lowered bone density â€“ a major problem among old people, but itâ€™s a concern for the young too since bone density that isnâ€™t acquired in youth is hard to get and density loss begins as early as the 40s for some people!
But the studies that suggest this link consuming sodas with low bone density. They donâ€™t demonstrate a casual relationship. People who drink a lot of sodas on a regular basis often have other unhealthy lifestyle factors in play: they donâ€™t eat as well. They donâ€™t drink as much milk, preferring another soda. Theyâ€™re often sedentary, since highly active people often choose water or sports drinks rather than gallon containers of own-brand fizz. So the real link is between poor diet and lifestyle, and poor bone density development: carbonated drink consumption is a symptom, not a cause.
Next up: drinking carbonated water either makes your stomach too acidic, or dilutes stomach acid, making the stomach environment less acidic. Either way, itâ€™s clearly bad for youâ€¦ but neither one is true.
Stomach acid is about 100 times more acidic than the most acidic of carbonated waters. Itâ€™s unaffected by the acidity of the water, even if you drink quite a lot of it. Itâ€™s also unaffected by being diluted in water, or in anything else. The acid in your stomach doesnâ€™t just sit there: itâ€™s generated by a mechanism in the stomach wall, that also has an effect on blood pH and on the release of basic bicarbonate into the stomach wall to regulate stomach acidity. Anything you put into this mix, whether itâ€™s too acidic, not acidic enough or dilutes the acid, will simply be compensated for by this mechanism.
In fact, some people have reported finding that drinking carbonated water can actually help with their stomach health. So studies were undertaken: one group drank 1.5 liters of still water every day, the other 1.5 liters of sparkling water. After a month, the still water group reported no change, while the sparkling water group reported reduced indigestion symptoms. Some reported relief from constipation too.
In fact, the assertations from various sources that carbonated water is dangerous have attracted the attentions of scientists who have researched the subject and found that there are no dangers. So where does all this worrying come from?
Well, there are some legitimate health concerns about carbonated water. Itâ€™s been suggested that it can interfere with kidney function and lead to dehydration. At first the blame for this was laid at the door of the caffeine many carbonated beverages contain. But caffeine has been exonerated â€“ and so has carbonation. Again, the likely culprit is sugar.
Carbonated beverages have been associated with irritable bowel syndrome and with triggering gastric reflux, and patients at several US hospitals are advised not to take carbonated drinks of any kind while suffering from gastric ulcers, though thereâ€™s no real evidence that carbonated drinks can irritate the ulcers.
Finally, there is the issue of additives. Some carbonated waters actually contain various flavourings and sweeteners, and these can have adverse health effects. But the sodium in sparkling waters has helped reduce the rates of cardiovascular problems in pregnant women in one US study.
To sum up, then: is carbonated water bad for you? No. In fact, it may even be good for you if you have gastric troubles. It wonâ€™t rot your teeth, stop you digesting your food, or make your bones brittle. But sugary fizzy drinks are best avoided or consumed in moderation.