The Ingredients in Diet Pepsi

Diet Pepsi is a popular cola that is calorie free. A host of ingredients go into this soft drink to give it flavor, color and to keep it fresh. While calorie free, Diet Pepsi is not caffeine free, so you need to factor its caffeine content into your daily intake. It also contains phenylalanine, for which the U.S. Food and Drug Administration requires a warning on the label.

Carbonated Water

Carbonated water is this beverage’s primary ingredient. Carbonated water was invented in the 18th century and has been popular since. It’s a solution of carbon dioxide in water under pressure, according to the Marshall Cavendish Corporation’s “How It Works: Science and Technology.” Carbonation gives the beverage its fizz and also works as a preservative 1.


There are 118 mg of aspartame in an 8-oz. serving of Diet Pepsi. Aspartame is an artificial sweetener that is high in phenylalanine, which is an essential amino acid. Diet soda labels feature a warning about phenylalanine due to the risk it poses to people who have phenylketonuria, or PKU 2. With this rare condition a person’s body cannot process phenylalanine. If you don’t suffer from PKU, you don’t have to worry about the phenylalanine in your soda, advises the


An 8-oz serving of Diet Pepsi has 24 mg of caffeine. Caffeine is a diuretic as well as a central nervous system stimulant, note the experts at the University of Maryland Medical Center. The recommended maximum daily caffeine intake for healthy adults is 400 to 450 mg a day. If you are a woman contemplating pregnancy, drop down to 300 mg per day. Kids ages 4 to 6 should only have 45 mg per day, according to C.A. Knight, lead author for a study in the December 2004 journal “Food and Chemical Toxicology. 3


Citric acid is a weak organic acid that serves as a natural preservative. It comes from fruit. It can be used to give soda both tartness and sweetness, according to the Science Encyclopedia. The phosphoric acid in Diet Pepsi is another weak acid that is a common ingredient in colas. It’s used to give it a tart flavor.

Potassium Benzoate

Potassium benzoate is a preservative that is used in Diet Pepsi. It inhibits growth of yeasts, bacteria and mold, according to the U.S. Food and Drug Administration. Potassium benzoate results in benzene in your cola. While benzene is a carcinogen that may cause cancer, Center for Food Safety and Applied Nutrition surveys indicate levels of benzene in beverages do not pose safety concerns for consumers because the levels are so low, notes the FDA.

Food Additives

Caramel color is a food additive used to enhance the product’s appearance. Natural flavor is another additive commonly found in everything from soft drinks to barbecue sauce to pudding, according to the FDA. Natural flavor ingredients are derived from natural food sources, according to the FDA.