First brewed by Dr. John Stith Pemberton in 1886, Coca-Cola has grown into the world's best-selling soda brand. According to trade publication "Beverage Digest," Coca-Cola held a 17 percent share of the U.S. soda market in 2009, selling nearly 1.6 billion cases. For all its successes, Coca-Cola has been singled out on numerous occasions for its negative health effects.
The possibility of spermicidal effects of Coca-Cola was first reported in 1985 in the New England Journal of Medicine. Two years later, researchers at Veterans General Hospital in the Republic of China found that while Coca-Cola did reduce sperm motility, it did not have a marked effect. In March 2010, Reuters reported the results of a Danish study showing that men who drank 32 ounces or more of Coca-Cola daily could reduce their sperm count by nearly 30 percent. The researchers believed that overall nutrition played a role as non-cola drinkers tend to eat more fresh fruits and vegetables, consume less caffeine and have an overall healthier lifestyle.
Coca-Cola is one of the most acidic beverages on the market. An interview with Dr. James McKay, formerly of the Naval Medical Research Institute, found that colas are closest in pH level to vinegar--between 2.0 and 3.4, according to the Food and Drug Administration. A 2006 study published in the journal Inflammopharmacology showed that rats fed Coca-Cola exhibited an increased secretion of stomach enzymes used to balance pH.
A 12-ounce service of Coca-Cola contains 64 mg of caffeine, according to "Neuroscience for Kids," the website of a University of Washington professor, Dr. Erik Chudler's. Dr. Chudler writes that caffeine takes effect when absorbed into the bloodstream by the stomach and small intestine, which can happen between 15 and 60 minutes after consumption. While many people rely on caffeine to keep them alert, caffeine can be dangerous as it constricts arteries and veins and boosts heart rates.
Doctors and nutritional experts caution against consuming large amounts of soft drinks because of their high sugar levels. A 12-ounce serving of Coca-Cola contains 39 grams of sugar, or 13 percent of the Food and Drug Administration's recommended daily allowance. Writer Wade Meredith traced the path of a Coca-Cola after it is consumed. Within the first 20 minutes, the body synthesizes the equivalent of 10 teaspoons of sugar, causing a blood sugar spike and massive insulin secretion by the pancreas. Within 60 minutes of drinking the soda, the sugar and insulin have passed through the digestive system. This generally leads to a "crash," or decline in stamina, as the sugar has been quickly absorbed and burned by the body for energy.