Coke vs Pepsi: Why Americans are so fiercely loyal to their soda of choice

The rivalry between Coca-Cola and Pepsi has been bubbling for generations, and a person's preference for one soda over the other likely involves a combination of factors.

The differences in the two sodas' ingredients could help reveal why some consumers prefer Coke to Pepsi, or vice versa, according to The Takeout. The outlet reported that Coca-Cola and Pepsi differ somewhat in their formulations. Pepsi contains citric acid, which Coca-Cola does not, and slightly more sugar per 12-ounce serving — about 41 grams to Coke's 39.

"Few consumer products have been part of culture for as long as cola," PepsiCo told Fox News Digital.

Fox News Digital also reached out to Coca-Cola for comment. 

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"People have known these brands for years, share them at meals and celebrations, and have developed strong personal connections along the way," PepsiCo added. "Combine that history with genuine differences in taste, and it's easy to see why the Pepsi-versus-Coke debate still inspires such strong opinions today."

A report by trade publication Beverage Digest revealed that Classic Coke was the top-selling soda in the U.S. in 2025, accounting for 18.5% of carbonated soft drink sales volume, while Dr Pepper held onto second place with an 8.8% share, reported the Atlanta Journal-Constitution.

Pepsi climbed back into third at 8.1% after falling to fourth behind Sprite in 2024. Pepsi ranked second in 2022 and third in 2023, when Dr Pepper edged past it by a fraction of a point.

Sales don't necessarily reflect taste preference, however.

A team of researchers from Baylor College of Medicine studied the Coke and Pepsi preferences of 67 people back in 2004. The scientists gave participants blind taste tests, then scanned their brains during tastings that involved cues such as flashes of light or pictures of a Coke or Pepsi can.

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The brain scans suggested that seeing the Coke brand influenced participants' preferences and activated areas of the brain associated with memory and executive deliberate decision-making, suggesting that marketing and cultural associations can influence what consumers think tastes better. 

The Pepsi can produced no comparable effect on the participants. The study was small, however.

"Nothing beats the taste of Coca‑Cola," The Coca-Cola Company declares on its website. "Designed to go with everything, the taste of the classic Coca‑Cola has remained unchanged for more than 130 years. Coca‑Cola is inviting the world to celebrate the real magic of humanity."

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In 1975, Pepsi fired an early shot in what became known as the "cola wars" when it launched what it called the Pepsi Challenge. The campaign invited consumers to sample Pepsi and Coca-Cola blindly and choose which they preferred. Pepsi declared that more people preferred its taste — and years of advertising urged consumers to "let your taste decide" by taking the challenge. 

No single ingredient defines Pepsi's taste, PepsiCo told Fox News Digital.

"Sweetness is one element of Pepsi's flavor profile," the company said. "Pepsi has been formulated to balance sweetness with tartness, bright citrus and spice notes, and crisp carbonation — creating the bold, refreshing taste consumers recognize as uniquely Pepsi."

PepsiCo believes it's a common misconception that people always know exactly which cola they prefer.

"Many have strong assumptions going in, but when Pepsi is put head to head against our competitor in a blind taste test, those assumptions are often challenged," the company said.

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It also said research shows "half of Coke buyers also purchase Pepsi in a given year." Taste is an important part of why people decide which soda to buy, the company said — but it isn't the sole deciding factor.

"Flavor design and complexity play a role in preference, and people can experience and describe taste differently," the company said. 

"But we don't believe cola preference can be explained by ingredients alone. The overall taste experience, personal preferences and the moments associated with a brand all contribute to why someone may prefer one cola over another."

Pepsi revived the Pepsi Challenge in 2025, putting Pepsi Zero Sugar head-to-head against Coke Zero Sugar and distributing more than 1 million samples across 34 markets in 23 states and Washington, D.C.

"We're confident in what happens when people have the opportunity to put assumptions aside and focus on taste alone," Pepsi said.

A December 2025 Pepsi press release said that "Pepsi Zero Sugar won 100% of the Pepsi Challenge national tour markets (including Coke's backyard – Atlanta!), achieving a consumer preference rate exceeding 60% across the U.S."

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The nutritional differences between Coke and Pepsi are "too small to matter" from a health perspective, Marion Nestle, professor emerita of nutrition, food studies and public health at New York University, told Fox News Digital.

"Both are sugary drinks with way too much sugar for the body to handle easily when consumed as a drink," Nestle said. "Large amounts of sugar in liquid form are absorbed rapidly by the digestive tract, causing insulin to spike and other hormonal changes, none of them beneficial."

An occasional 8-ounce Coke or Pepsi generally isn't a matter of concern, Nestle added.

"It's the larger ones that cause problems, especially when consumed frequently," she said. "Think of these drinks as instant candy."