UK Biobank data now link both sugar-sweetened and non-sugar-sweetened beverages to an increased risk of metabolic dysfunction–associated steatotic liver disease (MASLD).
Researchers observed that even drinks marketed as lower-calorie alternatives were associated with greater liver fat build-up. The analysis highlights potential metabolic trade-offs in beverage consumption across categories.
Researchers followed more than 103,000 adults without pre-existing liver disease for about 10 years. During that time, 949 participants developed MASLD and 103 died from liver-related causes.
Those who drank more than one can (about 330 grams) daily of either sugary or diet sodas were more likely to develop MASLD. Sugar-sweetened drinks were tied to a roughly 50% greater risk, while low- or non-sugar beverages were linked to about 60% higher risk.
“Our research shows that low- or non-sugar-sweetened beverages (LNSSBs), often seen as healthier alternatives because they use sugar substitutes, may not be entirely risk-free. We found that frequent consumption was still linked with liver health risks, which challenges the common belief that these drinks are completely ‘safe’ or ‘healthy’ substitutes for sugary beverages.” Lihe Liu, a graduate student at Soochow University and the study’s lead author, explained.
The findings, presented at the United European Gastroenterology Week 2025, also revealed that only low- or non-sugar beverages were associated with higher liver-related mortality, and the relationship appeared dose-dependent.
Substitution models suggested that swapping a can of soda—of either kind—for water reduced MASLD risk, with a slightly larger effect for sugary drinks (around 14.7% lower risk). Liu added, “Clinically, this highlights the need to guide people towards healthier beverage choices, with water remaining the safest and healthiest option.”
Registered dietitian Karen Z. Berg, who was not involved in the research, agreed: “Many people have the misconception that diet drinks are healthier … Plain water, fruit-infused water, or seltzer [are] the way to go.”
While the study has yet to be peer-reviewed, its results raise new questions about whether both sugary and “diet” beverages deserve a place in a healthy lifestyle.