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A new study suggests heavy diet soda consumption may raise the risk of metabolic dysfunction-associated steatotic liver disease (MASLD). Jonathan Knowles/Getty Images
  • Diet sodas are often marketed as products that help with weight management.
  • A new study suggests that heavy diet soda consumption may promote metabolic dysfunction-associated steatotic liver disease (MASLD) onset by increasing body mass index (BMI).
  • Prior studies suggest that diet soda consumption is linked to higher BMI and blood pressure.
  • Health experts agree that diet sodas may promote weight gain and liver disease.
  • Excessive intake of artificial sweeteners found in diet sodas may also raise the risk of type 2 diabetes.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the most prevalent liver diseases. Current estimates suggest MASLD affects up to 46% of the world’s population.

MASLD was formerly called nonalcoholic fatty liver disease (NAFLD) and renamed in June 2023.

The disease, marked by excess fat accumulation in the liver, has no initial symptoms. It can progress to metabolic dysfunction-associated steatohepatitis (MASH), a more serious condition that can lead to liver scarring and cirrhosis.

Currently, no medication has been approved to treat this form of liver disease. Doctors recommend exercise and dietary changes to help reduce body fat in preventing or reversing MASLD.

Health experts have long considered that soda consumption may increase MASLD risk by inducing insulin resistance and inflammation in the liver.

While diet sodas often tout claims like “zero sugar” and “zero calories,” these are not considered healthful beverages by experts.

Now, a research team set out to find an association between heavy consumption of diet soda and MASLD risk. Their work, recently published in BMC Public Health, suggests a strong correlation between diet sodas and this form of liver disease.

“To the best of our knowledge, this is the first study to explore the association between diet soda consumption and MASLD in a nationally representative sample, and our findings can provide valuable dietary recommendations for the prevention and treatment of MASLD,” the study authors wrote.

Sodas are carbonated, nonalcoholic beverages. Marketers have promoted diet sodas in response to concerns about obesity.

Zero sugar and zero calories beverages have grown in popularity in recent years, but they often contain aspartame or other chemical sweeteners.

Recent research continues to link heavy consumption of artificial sweeteners with increased risks of obesity, type 2 diabetes, and other markers of metabolic syndrome.

In May 2023, a new guideline from the World Health Organization (WHO) advised against using non-sugar sweeteners to reduce body fat. In July 2023, the WHO labeled aspartame as “possibly carcinogenic to humans”.

Some research has suggested that diet sodas may contribute to increased body mass index (BMI) and percentage body fat in adolescents.

Daily soda intake is also associated with increased hypertension in adolescents. Furthermore, excessive diet soda consumption may be involved in increased risk of vascular events and type 2 diabetes.

Prior research has suggested that artificial sweeteners may promote insulin resistance and glucose intolerance by disrupting intestinal microbiota. Both reactions are closely related to the development of MASLD.

Medical News Today discussed this study with Dr. Menka Gupta of Nutranourish, a functional medicine provider. She was not involved in the present research.

Dr. Gupta hypothesized that artificial sweeteners may affect the liver via the gut-brain axis. She explained to MNT:

“The gut-brain axis involves bidirectional communication between the gastrointestinal tract and the central nervous system. Artificial sweeteners in diet soft drinks can impact the gut microbiota composition, which in turn can impact this axis. This can influence metabolic processes and potentially contribute to liver-related conditions.”

To find the connection between diet sodas and MASLD, the present study’s authors analyzed data from the National Health and Nutrition Examination Survey (NHANES).

The United States’ National Center for Health Statistics sponsors this program to evaluate the health and nutritional conditions of the American population.

Detailed records of diet soda consumption were only available during the 2003–2006 dietary interviews. The study authors examined information on a total of 2,378 participants.

The final study assessment categorized 1,089 people with MASLD and 1,289 with no MASLD.

The NHANES database had no data on liver transient elastography, so the Fatty Liver Index (FLI) was used to determine MASLD status.

Responses to the food frequency questionnaire informed the assessment of diet soda consumption frequency. The answers to the question “How often do you drink diet soft drinks?” included:

  • never
  • rarely
  • sometimes
  • always

The researchers adjusted their results for confounding variables among participants, including:

  • age
  • gender
  • ethnicity
  • smoking status
  • average daily physical activity
  • carbohydrate intake
  • hypertension
  • diabetes

Males made up 54.6% of the MASLD group, and the MASLD group’s diet soft drink intake was dramatically higher than the non-MASLD counterparts’ reported consumption.

Hypertension, hyperlipidemia, and diabetes were also significantly more prevalent among the MASLD population than in the non-MASLD group.

Dr. Gupta shared: “The inclusion of mediation analysis to explore the potential mediating role of BMI provides insights into the mechanisms underlying the association between diet soft drink consumption and MASLD.”

The study’s authors also tested their hypothesis that BMI may be a mediating factor in MASLD.

After accounting for age, gender, race, dietary factors, and cardiometabolic conditions, the team found that diet soda consumption “was positively associated with the occurrence of MASLD.”

The scientists also noticed a positive correlation between BMI and MASLD.

“It was estimated that 84.7% of the total association between diet soft drink consumption and MASLD was mediated by BMI,” the researchers reported.

Dr. Gupta said she was impressed with the study’s large sample size and adjustments for potential demographic, lifestyle, and metabolic syndrome-related confounders.

But she and the study’s authors noted a few drawbacks to the new research.

First, FLI was used instead of the imaging method widely used in clinics. Although FLI has been validated, Dr. Gupta said that it could falsely indicate the presence of fatty liver or fail to detect it.

As the study’s authors mentioned, the cross-sectional design could have made reverse causality possible. In other words, people diagnosed with MASLD may have altered their diet soda intake in response to the diagnosis.

“Using self-reported data is subject to recall bias, [and] the study didn’t use detailed dietary records or biomarkers such as metabolites,” Dr. Gupta said.

She also said that BMI as an obesity marker has its own limitations, as it doesn’t distinguish between muscle and fat mass, or consider fat distribution. Neither does it provide information about metabolic health.

Lastly, this work did not account for genetic variants or sleep patterns, both of which are risk factors for MASLD.

The study’s authors believe that randomized controlled trials (RCTs) will be needed to provide more robust evidence for their findings.