New research suggests that drinking even one can of diet soda per day may increase the risk of nonalcoholic fatty liver disease (NAFLD) by 60%, while consuming a sugary beverage could raise the risk by 50%.
NAFLD, also known as metabolic dysfunction-associated steatotic liver disease (MASLD), occurs when fat builds up in the liver of people who drink little to no alcohol. The condition can lead to cirrhosis, liver cancer, and other severe complications. In the United States, NAFLD prevalence has surged by 50% over the past three decades, now affecting roughly 38% of the population.
Lead study author Lihe Liu, a graduate student in gastroenterology at Soochow University in China, said the findings challenge the perception that diet drinks are harmless. “Our study shows that low- or non-sugar-sweetened beverages were linked to a higher risk of MASLD, even at modest intake such as a single can per day,” Liu said.
The study followed nearly 124,000 participants without liver disease over a 10-year period using data from the UK Biobank. Researchers tracked beverage consumption through 24-hour dietary questionnaires and found that substituting water for sugary drinks lowered the risk of MASLD by nearly 13%, and by over 15% when replacing diet drinks. Switching between sugary and diet beverages did not reduce risk.
Experts say sugary drinks can promote fat accumulation in the liver through spikes in blood glucose and insulin. Diet drinks, though low in calories, may still impact liver health by altering the gut microbiome, stimulating insulin secretion, and increasing cravings for sweet foods.
“Water hydrates without affecting metabolism, supports satiety, and promotes overall metabolic function,” Liu explained. “Replacing sweetened drinks with water is the healthiest choice.”
The study was presented at the United European Gastroenterology Week in Berlin and is awaiting peer-reviewed publication.
