In this cross-sectional study of Korean adults, we demonstrated that a higher consumption of soft drinks, specifically more than one serving (200 mL) per week, was significantly associated with an increased risk of MASLD, whereas a higher consumption of traditional Korean drinks (> 200 mL per week) was significantly associated with a lower risk of MASLD after adjusting for several covariates. No association was observed between fruit drink consumption and MASLD. When stratified by sex, a significant positive association between soft drinks and MASLD was observed only in females, and a suggestive inverse association between traditional Korean drinks and MASLD was observed in males.
SSBs are consumed globally, with consumption increasing rapidly in low- and middle-income countries and exceeding the daily free sugar intake limit in many high-income countries. Several meta-analyses and prospective cohort studies have provided strong evidence of an association between SSB consumption, weight gain, and cardiometabolic diseases. Since early Israeli studies reported that patients with NAFLD consume more SSBs, especially soft drinks, than the general population, gradually accumulating evidence has suggested a relationship between SSB consumption and NAFLD development.5,11,12
This is the first study to examine the effects of SSB on MASLD using the most recently suggested concept. In line with our study, a cross-sectional study of US adults from the Framingham Heart Study's Offspring cohort and Third Generation cohort revealed a 56% higher risk of NAFLD in daily SSB consumers, defined by abdominal scan (≥ 8 ounces/day), compared to those who did not consume SSB. Another cross-sectional study of US adults from the National Health and Nutrition Examination Survey reported that people who consumed more than one serving per day (> 8 ounces/day) had 1.5 times higher odds of having liver stiffness, defined by liver stiffness measurements of > 7, and 2.1 times higher odds of having hepatic steatosis, defined by a controlled attenuation parameter of > 248, compared to non-SSB consumers. A prospective cohort study from Australia also reported that SSB consumption > 197.2 g per day was associated with a higher risk of NAFLD. In China, a cross-sectional study reported that soft drink consumption of more than one cup (200–230 mL) per week was associated with a higher prevalence of NAFLD, defined by elevated ALT (OR: 1.32; 95% CI: 1.13–1.53), and a prospective cohort study showed that same amount of SSB consumption was associated with increased risk of NAFLD incidence (HR: 1.18; 95% CI: 1.03–1.34).13,14 Despite the overall comparability in the direction of association between the present and previous studies, the definition of liver disease and the amount of SSB consumption between Asian and Western countries differ.
In the present study, unlike soft and traditional Korean drinks, fruit drinks were not associated with MASLD. Although fruits contain fructose, they are generally considered to have little obesogenic potential and are beneficial for the prevention and progression of NAFLD. This may be because many antioxidants contained in fruits inhibit the metabolic effects caused by fructose. Similarly, several studies have reported that 100% fruit juice helps prevent and improve NAFLD, possibly because it contains phytochemicals such as anthocyanins, polyphenols, and resveratrol. The observed null association between fruit drinks and MASLD may be because the fruit drinks in our study included not only 100% fruit juice but also fruit-flavored drinks and sugar-added fruit juice. As fruit drinks were assessed using a single aggregated item, it was challenging to distinguish specific fruit drink items in their current form. Therefore, further analyses should be conducted by classifying fruit drinks by type to evaluate the effects of fruit juice consumption on MASLD accurately.
Interestingly, we observed that the consumption of traditional Korean drinks, including Sikhye and Misu, was inversely associated with the risk of MASLD. This is thought to be mainly because these drinks contain a minimal amount of fructose compared to soft drinks. In addition, the malt extracts used in the manufacturing process of Sikhye have been reported to have antioxidant activity, which may prevent the occurrence of NAFLD. Several studies have reported that hepatic fat content decreases when SSB consumption is replaced with low-calorie sweetened (LCS) beverage consumption.15–17 However, the effect of long-term consumption of LCS beverages on cardiometabolic health remains unclear. Therefore, many guidelines by diabetes and nutrition societies do not support the use of LCS beverages and recommend water instead of SSB. However, water may not be an appropriate alternative for patients who habitually consume soft drinks. In this case, traditional Korean drinks may serve as alternatives to soft drinks to reduce the occurrence of MASLD. Randomized controlled studies are needed to determine whether replacing soft drinks with traditional Korean drinks can prevent the development of MASLD.
In our sex-stratified analyses, an increased risk of MASLD was observed across the soft drink consumption group in females but not in males. In the general population, the overall prevalence of MASLD is higher in males than in females, with evidence suggesting that estrogen has protective effects against MASLD. However, some studies have reported that females may be more susceptible to fructose-induced fatty liver disease. In an experimental study involving male and female Wistar rats (n = 24 male and 24 female) fed a high-fructose diet for 10 weeks, Hyer et al. reported that female rats showed extensive NAFLD-like liver pathology, whereas male rats showed minimal liver pathology. In a randomized crossover study involving 16 healthy adults (eight men, eight women), Low et al. reported that the intake of a high-fructose meal increased postprandial hepatic de novo lipogenesis to a greater extent than the intake of a low-fructose meal in women but not in men. However, previous experimental studies on NAFLD in mice fed altered diets reported conflicting results, with more severe disease in males; therefore, further research is needed to determine the sex-specific effects of fructose on NAFLD.18,19
The present study had some limitations. First, a possible misclassification of MASLD may have occurred because we defined MASLD using the HSI scoring system rather than liver biopsy. However, since the HSI is a screening tool designed based on Korean health check-up data and is a well-validated score in Korean and Asian populations, the diagnostic accuracy for NAFLD in this study conducted on Koreans is expected to be high.20–22 Second, due to inevitable measurement errors of the FFQ, we may have misclassified SSB consumption, which may attenuate the true association. However, consumption assessed using the FFQ is cost-effective in large-sample studies and accurately represents the usual intake of individuals. Third, the cross-sectional design of the present study limits the ability to assess the causality between SSB consumption and the occurrence of MASLD. Long-term prospective studies are required to evaluate the causal relationship between SSB consumption and the occurrence of MASLD. Fourth, the magnitude of the association may have been affected by residual confounding factors from unmeasured or unknown factors. Fifth, our study was conducted on Korean adults aged 40–64 years; thus, the results may not be generalizable to different study settings.
In conclusion, soft drink consumption of at least one serving (200 mL) per week was positively associated with MASLD occurrence, whereas the same amount of traditional Korean drink consumption was inversely associated with MASLD in a nationally representative sample of Korean adults. Our results suggest that the effect of SSBs on MASLD may differ depending on the type of SSBs; soft drink consumption should be limited, and traditional Korean drinks can be consumed in moderation by Korean adults to improve liver health.