Olympic swimmers are employing a unique strategy to combat E. coli contamination by consuming Coca-Cola as a preventive measure.

Coca-Cola is not only an official sponsor of the Paris Olympics, but it has also received positive feedback from some athletes. Olympic swimmers have been consuming Coca-Cola after events due to its purported ability to prevent bacterial infections and stomach problems, which are significant concerns for those swimming in the heavily polluted Seine River.

“The myth of Coca-Cola is true,” Moesha Johnson, an Australian marathon swimmer, told the Wall Street Journal. “We will often have a Coca-Cola afterwards just to try to flush out anything inside of us.”

In the realm of anecdotal remedies, the consumption of Coca-Cola after immersion in the Seine River has been suggested as a potential antidote to gastrointestinal discomfort. Fizzy beverages have historically been employed as a folk remedy for digestive distress, with the underlying belief that the effervescence has a calming effect on the stomach and the sugars replenish glucose levels. However, medical professionals generally do not endorse this approach, favoring natural anti-inflammatories such as ginger over sugar-laden beverages that may exacerbate stomach upset. Nonetheless, some long-distance runners maintain their belief in the efficacy of Coca-Cola as a late-race energy booster.

The Coca-Cola Company has faced criticism from health experts who allege that the company engages in “sportswashing” by promoting sugary soft drinks and from environmental activists who object to the distribution of the drink in plastic bottles during sporting events. Coca-Cola maintains that it offers sugar-free alternatives, and the Olympics Committee continues to support its partnership with the beverage brand.

Despite the purported health benefits of the soda, concerns have arisen regarding the cleanliness of the Seine due to its popularity as a purported remedy for stomach ailments. Professor Davey Jones, an expert in environmental science and public health at Bangor University, shared with BBC Science Focus that the river, which hosted triathlon and swimming marathon events, is teeming with unsavory microorganisms, including bacteria and viruses. The presence of E. coli in the Seine, an indicator of sewage or animal feces contamination, suggests the potential presence of norovirus, a prevalent cause of gastroenteritis characterized by cramps, vomiting, and diarrhea.

“Whenever there’s sewage overflow, for example, into the Seine, norovirus gets released into the water,” Jones said. “You only need, in theory, to ingest one to ten viral particles to get sick. And when we’re sick, every time we go to the toilet, we emit trillions of these viral particles.”

E. coli’s remarkable capabilities in the context of the Olympic Games

The presence of bacterial and viral particles in the Seine River has garnered significant attention in the lead-up to and during the Olympic Games. At the commencement of the games, pollution levels in the Seine caused a one-day postponement of the men’s triathlon event, as officials deemed it necessary to cancel a training session due to elevated E. coli levels detected in water tests conducted after a heavy rainfall. Consequently, two triathlete swimmers withdrew from the competition due to illness, although neither athlete explicitly attributed their condition to swimming in the Seine.

“For the moment, there is no direct link between the Seine and any illness,” Paris deputy mayor Pierre Rabadan said in a press conference Monday.

Concerns about the cleanliness of the Seine River have existed for decades, not just prior to the Olympics. The river, a crucial artery in the heart of Paris, has been considered a source of pollution due to its combined sewage and stormwater system. After prolonged periods of rainfall, untreated waste flows directly into the Seine.

Despite long-standing promises from Paris to address the river’s pollution, the Olympic deadline accelerated the project. The city invested $1.5 billion in river cleanup efforts, including the construction of a substantial underground basin to divert rainwater for treatment before it enters the river. Paris Mayor Anne Hidalgo even pledged to swim in the river after the cleanup. However, skeptics expressed their doubts, with some threatening to hold a protest by defecating in the river before the officials’ promised swim.

The future of the Seine remains uncertain. Although the city’s cleanup efforts enabled successful Olympic events in the river, sporadic heavy rainfall continues to jeopardize safe water conditions. Given the increased frequency and unpredictability of extreme weather due to climate change, addressing the treatment of the Seine and finding sustainable solutions to pollution pose ongoing challenges.

“The success will be complete if politicians and scientists keep up their efforts for the next few years,” Jean-Marie Mouchel, professor of hydrology at Sorbonne University, told Wired.