Diet Coke Versus Diet Pepsi

When it comes to diet cola drinks, the two most popular products are Diet Coke and Diet Pepsi. Here's a little background information on each including their history, ingredients, nutritional value, and why you might consider choosing one drink over the other.

Diet Coke

Diet Coke was introduced in 1982 to counter the growing popularity of Diet Pepsi. The drink has been a huge success for the Coca-Cola Company and it is now the No. 3 soft drink in the world. It outsells Diet Pepsi by about 2 to 1 in the United States. In 2010, Diet Coke had a 10% market share versus 5% for Diet Pepsi.

Diet Coke is also known as Diet Coca-Cola, Coca-Cola Light, or Coke Light. The "Light" designation is typically used in countries outside the U.S.

Diet Pepsi

Diet Pepsi was first introduced in 1963 under the name Patio Diet Cola and was re-branded the following year as Diet Pepsi. At that time, the diet soft drink competition consisted of Coca-Cola's Tab soda and Diet Rite soda, produced by Royal Crown. Diet Pepsi became the first diet cola to be distributed on a national scale in the United States.

Diet Pepsi's primary competition was Tab until the introduction of Diet Coke in 1982. The two brands have been going at it ever since although Diet Coke currently outsells Diet Pepsi by a comfortable 2 to 1 margin.


Diet Coke and Diet Pepsi share many of the same ingredients but in different proportions. These include: carbonated water, caffeine, caramel coloring, phosphoric acid, citric acid, natural flavors, and aspartame.

In the U.S., the ingredients of Diet Pepsi are carbonated water, caramel color, aspartame, phosphoric acid, potassium benzoate (preserves freshness), caffeine, citric acid, and natural flavor. The ingredients vary slightly in other countries, mainly in terms of the artifical sweeteners used. For example, in Canada and the UK, the drink contains acesulfame potassium in addition to aspartame.

Caffeine and Nutrition Information

A 12-ounce can of Diet Coke contains 40 mg sodium, 45 mg caffeine, and 18 mg potassium. A 12-ounce can of Diet Pepsi contains 35 mg sodium, 35 mg caffeine, 30 mg potassium, 41 mg phosphorous, and 177 mg aspartame.

There is no nutritional advantage of one drink over the other. Both have 0 calories (which technically means fewer than five calories per serving), 0 carbohydrates, 0 protein, and no healthy vitamins or minerals such as calcium or iron.

Taste Preference

Diet Pepsi and Diet Coke cost approximately the same so selecting one drink over the other is really a matter of individual taste preference. And it seems that once you develop a taste for a given product, you're likely to stick with that product.