Coca Cola is the most popular soda in the world today, and it owes much of its initial success to the inclusion of two potent chemicals which are its namesake. These are the kola nut and the coca leaves. These two stimulants were part of a larger group of nervines, and were popular ingredients in soda fountains beverages served in pharmacies in the late 19th century.
These stimulating ingredients were marketed as a brain tonic, to cure headaches and improve wakefulness.
However, these chemical stimulants caused some trouble with law makers. According to Frederick Allen, author of “Secret Formula: How Brilliant Marketing and Relentless Salesmanship Made Coca-Cola the Best-Known Product in the World” (1999)
In 1891, “The first stirrings of a national debate had begun over the negative aspects of cocaine, and the manufacturers were growing defensive over charges that use of their products might lead to “cocainism” or the “cocaine habit”. The full-throated fury against cocaine was still a few years off, and [Coca Cola Company owner Asa Griggs] Candler and Robinson were anxious to continue promoting the supposed benefits of the coca leaf, but there was no reason to risk putting more than a tiny bit of the coca extract in their syrup. They cut the amount to a mere trace.
But neither could Candler take the simple step of eliminating the fluid extract of coca leaves from the formula Candler believed that his product’s name had to be descriptive, and that he must have at least some by-product of the coca leaf in the syrup (along with some kola) to protect his right to the name Coca-Cola. Protecting the name was critical. Candler had no patent on the syrup itself. Anyone could make an imitation. But no one could put the label ‘Coca Cola’ on an imitation so long as Candler owned the name. The name as the thing of real value, and the registered trademark was its only safeguard. Coca leaves had to stay in the syrup.”
Coca was finally removed from the formula in 1929.