Tonic water is a carbonated beverage that derives its somewhat bitter taste from the addition of quinine, which also makes it glow when exposed to UV light. It usually is flavored with lemon or lime and lots of sugar, and it often contains caffeine. This beverage is frequently used in mixed cocktails, most famously in gin and tonic, although vodka with tonic water also is popular. Tonic water also can be used with sweet alcohols, such as vermouth, to produce a balanced taste.
First patented during the mid-19th century in England, this beverage owes its popularity to an urban legend based on the properties of quinine. Quinine is a chemical compound that occurs naturally in the bark of the cinchona tree, which is grown in the tropical forests of South America. During the 17th century, after it had been taken to Europe, quinine became recognized as a relatively safe treatment for malaria. The British occupation of India, for example, was helped by quinine because its use allowed the British officers to stay healthy instead of succumbing to malaria.
Masking Quinine's Taste
One drawback of the use of quinine is that it is widely considered to taste bad. British soldiers would often take this bitter medication in a diluted form. The preferred mixture in which to dilute the quinine was a great deal of gin, some lemon or lime and a little sugar. When quinine-containing tonic water was first produced, many people concluded that a few gin and tonics would be good for one's health and help prevent malaria.
Not Effective as a Malaria Treatment
Quinine, however, has not been found to prevent malaria, it merely can treat it. A normal amount of tonic water also contains too little quinine to effectively treat malaria. Someone would need to drink at least 60 fluid ounces (1.77 liters) of tonic water a day — or the equivalent of 10 gin and tonics — to treat malaria. Chemically produced quinine in much larger doses is the preferred treatment for reducing fever and other malarial symptoms. In most cases, malaria also needs to be treated with antibiotics to produce full recovery.
Although tonic water lacks enough quinine to reduce the symptoms of malaria in normal amount, it still is known as a tonic — meaning that it is essentially healthful — because of its use of quinine. There is no known health benefit from consuming tonic water, which has a sugar content that is equivalent to that of most sodas. Nevertheless, the name has stuck, and the drink remains popular.