Both sugary and diet drinks linked to 50-60% higher liver disease risk

A study of nearly 124,000 people in the UK has upended a common assumption about diet drinks: that swapping regular soda for artificially sweetened alternatives is a smarter choice for your health. Researchers found that both types of beverages—sugary and sugar-free alike—carry roughly the same risk of developing a serious liver condition, and in some cases, the diet versions posed an even graver threat.

The work, presented at UEG Week 2025, tracked 123,788 participants from the UK Biobank who had no liver disease when the study began. Over a median follow-up of 10.3 years, researchers used repeated 24-hour dietary questionnaires to measure what people drank, then watched to see who developed metabolic dysfunction-associated steatotic liver disease, or MASLD—a condition in which fat builds up inside the liver. The numbers were sobering: 1,178 participants developed the disease during the study period, and 108 died from liver-related causes.

When people consumed more than 250 grams of sugar-sweetened beverages daily—roughly a can and a half of soda—their risk of developing MASLD climbed by 50 percent. Those drinking the same amount of artificially sweetened drinks faced a 60 percent increase in risk. What made the diet drinks particularly concerning was their association with liver-related death. No such link emerged for regular sugary drinks. Both types of beverages were also tied to higher fat content in the liver itself.

Lihe Liu, the study's lead author, noted that the findings challenge a widespread belief. "SSBs have long been under scrutiny, while their 'diet' alternatives are often seen as the healthier choice," Liu said. "Both, however, are widely consumed and their effects on liver health have not been well understood." The research suggests that even modest consumption of artificially sweetened drinks—as little as one can per day—carried measurable risk.

The mechanisms behind these dangers appear to differ between the two beverage types. Regular sodas spike blood glucose and insulin levels rapidly, promote weight gain, and increase uric acid—all pathways that lead to fat accumulation in the liver. Artificially sweetened drinks may work differently, potentially by reshaping the bacteria in the gut, disrupting the body's sense of fullness, intensifying cravings for sweet foods, and even triggering insulin release despite containing no sugar.

The study offered one clear protective measure: replacing either type of drink with water. Switching from sugary beverages to water reduced MASLD risk by 12.8 percent; switching from diet drinks to water cut risk by 15.2 percent. Notably, replacing one type of soda with the other offered no protection at all. "The safest approach is to limit both sugar-sweetened and artificially-sweetened drinks," Liu said. "Water remains the best choice as it removes the metabolic burden and prevents fat accumulation in the liver while hydrating the body."

The findings arrive as MASLD has become a global health crisis. Once known as nonalcoholic fatty liver disease, the condition now affects an estimated 30 percent of people worldwide and represents the most common chronic liver disease. Over time, fat in the liver triggers inflammation, leading to pain, fatigue, and loss of appetite. The disease is also a rapidly rising cause of death from liver failure. Researchers say their work supports a comprehensive rethinking of beverage consumption as part of broader efforts to protect not just liver health but also heart and kidney function. The team plans to pursue deeper investigation through randomized trials and genetic studies, focusing on how sugar and its substitutes interact with the gut microbiome to influence disease development.