Many consumers today are shying away from soft drinks because of legitimate concerns about their sugar or artificial sweetener content and are gravitating towards plain carbonated water. This has triggered questions about the safety of this beverage. First, a bit of background.
Naturally carbonated waters have long been believed to be healthy. Historically, people suffering from kidney stones, arthritis and "lack of vigour" flocked to spas such as Harrogate and Buxton in England and Pyrmont in Germany to partake of the waters. But if you couldn't get to the source, you were out of luck. That is until Joseph Priestley came along. Priestley, who is best known as the discoverer of oxygen, although he never recognized it as an element, lived next to a brewery and was intrigued by the bubbles of carbon dioxide he saw rising in beer. This gave him the idea of artificially carbonating water.
Priestley knew about the supposed therapeutic properties of the sparkling water that emerged from the 鈥淰apor Cave鈥� of Pyrmont in Germany. This water was thought of as medicine, much like other spring waters. Could he reproduce this water, Priestley wondered? Joseph Black had already shown that carbon dioxide, or "fixed air" as it was called, could be produced by reacting chalk (calcium carbonate) with sulfuric acid. Priestley designed a clever apparatus that linked a glass vessel in which the reagents were mixed to a pig bladder that in turn was connected to a tube leading into a water-filled bottle that sat inverted in a basin of water. The gas was generated, filled the bladder, which was then squeezed to pump pressurized gas through the water. By this method, enough of the gas dissolved to produce an acceptable bubbly beverage. Salts such as sodium carbonate or sodium tartrate could be added to produce "mineral water.
Priestley believed his carbonated water could prevent scurvy and managed to convince explorer James Cook to take some of his carbonated water along on his second voyage which was planned to circumnavigate the globe. Why Cook agreed is curious, because on his first voyage he had already discovered that fermented cabbage, or sauerkraut, can prevent scurvy.
Scottish physician John Nooth heard about the supposed curative properties of Priestley鈥檚 water and wondered why these had not been extensively investigated. He believed he had an answer. The water, Nooth said, had a 鈥渦rinous鈥� flavor from the pig bladder Priestley had used to store it. He proposed to get around the problem by designing an apparatus made totally of glass to carbonate water. Priestley did not take the criticism of his water well and maintained that neither he, nor anyone he ever offered the water to, had ever noted a urine smell or flavor. If Dr. Nooth had found his water tainted, Priestley suggested, it must have been because one of his servants had played a cruel trick and urinated into Priestley鈥檚 water that he brought to Nooth. Priestley had no foundation for this accusation and eventually gave up his attack on Nooth and accepted the Nooth Apparatus as superior to his own. Eventually, Jacob Schweppe, a Swiss inventor scaled up the apparatus, added a pressure pump, and made carbonated water available to all. In 1851 the public that came to the Great Exhibition in London was welcomed by a giant fountain that spewed Schweppes鈥� carbonated water.
Today, if you want to make some carbonated water you don鈥檛 need a Nooth apparatus. You can purchase a 鈥淪odaStream鈥� device that will automatically add bubbles to your water from a carbon dioxide cylinder. Is it safe? Yes! The dissolved carbon dioxide does form carbonic acid but the contact time of the carbonated water with teeth is too short to cause any damage to the enamel.
One small study with the intriguing title, 鈥淐arbon dioxide in carbonated beverages induces ghrelin release and increased food consumption in male rats: Implications on the onset of obesity鈥� found a potential problem. Ghrelin is a hormone that increases the appetite. What to make of this? If you have male rats and are concerned about their girth, keep them away from your carbonated water. As far as humans go, the only side effect that might arise from drinking carbonated water is the emission of carbon dioxide gas from either end of the digestive tract.
While the supposed health benefits of carbonated water are debatable, the financial benefits are not. The whole soda pop industry is of course based on artificially carbonated water. Here the carbon dioxide is not a problem but the sugar sure is!
