Researchers compared the eating habits and gut bacteria of 25 people with a fatty liver disease called MASLD to 25 healthy people. They found that people with MASLD ate less fiber, nuts, seeds, and healthy fats, and had different types of gut bacteria. The study suggests that eating more Mediterranean-style foods—like vegetables, whole grains, nuts, and fish—might help restore healthy gut bacteria and improve liver health. While this is promising, more research is needed to confirm whether changing your diet can actually reverse the disease.

The Quick Take

  • What they studied: Whether people with a fatty liver disease have different eating patterns and different types of gut bacteria compared to healthy people
  • Who participated: 25 adults diagnosed with metabolic-associated steatotic liver disease (MASLD, a condition where fat builds up in the liver) and 25 healthy adults with no liver disease
  • Key finding: People with MASLD ate significantly less fiber, omega-3 fatty acids from fish, nuts, seeds, whole grains, and vegetables. They also had lower amounts of ‘good’ bacteria and higher amounts of ‘bad’ bacteria in their guts compared to healthy people
  • What it means for you: Eating more Mediterranean-style foods (vegetables, whole grains, nuts, fish, and olive oil) may help restore healthy gut bacteria, which could potentially improve liver health. However, this study only shows a connection—it doesn’t prove that changing your diet will cure the disease. Talk to your doctor before making major dietary changes

The Research Details

This was a case-control study, which means researchers compared two groups: people with MASLD and healthy people without the disease. They looked backward at what these people had eaten over three days and analyzed their gut bacteria using advanced DNA testing. The researchers recorded everything the participants ate and drank, measured their liver health markers through blood tests, and identified which bacteria lived in their guts using a technique called shotgun metagenomic sequencing—basically, they read the genetic code of all the bacteria in stool samples to see exactly which species were present and in what amounts.

Understanding the connection between what we eat, our gut bacteria, and liver disease is important because it could lead to new treatments. Instead of just telling people to lose weight, doctors might be able to recommend specific foods that help restore healthy gut bacteria and improve the gut-liver connection. This approach could be more targeted and effective than general weight loss advice alone.

This study has some strengths: it used advanced genetic testing to identify bacteria accurately, and it carefully recorded what people ate. However, it has important limitations: the sample size was small (only 50 people total), it only looked at one point in time rather than following people over months or years, and it can’t prove that diet changes will actually improve the disease. The findings suggest a connection but don’t prove cause-and-effect.

What the Results Show

People with MASLD ate significantly less dietary fiber compared to healthy people—this is important because fiber feeds the good bacteria in your gut. They also consumed less omega-3 fatty acids (healthy fats found in fish), fewer nuts and seeds, less whole grain bread and cereals, and fewer vegetables overall. The gut bacteria differences were striking: people with MASLD had lower amounts of four specific types of ‘good’ bacteria that are thought to protect liver health, including Faecalibacterium, which is known to be beneficial. At the same time, they had higher amounts of Ruminococcus torques, a bacteria associated with less healthy outcomes. The researchers also found that the bacteria in people with MASLD were less able to perform certain important functions, like producing certain amino acids and B vitamins that the body needs.

The study found that the harmful bacteria and reduced bacterial functions in MASLD patients were connected to eating more added sugars and saturated fats (like butter and fatty meats), while the beneficial bacteria were connected to eating more unsaturated fats (like olive oil) and fiber. This suggests that the Mediterranean diet—which emphasizes these healthier foods—might help restore the right balance of gut bacteria. The researchers also noted that the bacteria in MASLD patients showed reduced ability to produce certain protective compounds and vitamins.

Previous research has shown that the gut microbiota (the community of bacteria in your digestive system) plays an important role in liver disease. This study adds to that knowledge by showing specific bacteria and specific foods that are connected to MASLD. It supports the idea that the ‘gut-liver axis’—the connection between your gut health and liver health—is real and important. However, most previous studies focused only on weight loss as treatment; this study suggests that the types of foods you eat matter beyond just calories.

The biggest limitation is the small sample size—only 50 people total, which means the results might not apply to larger populations. The study only looked at what people ate for three days, which might not represent their typical eating patterns. It’s a snapshot in time, not a long-term follow-up, so we don’t know if these dietary differences cause the bacterial changes or if the bacterial changes cause people to eat differently. The study can’t prove that changing your diet will actually improve MASLD because it didn’t test that. Additionally, the study didn’t account for other factors that might affect gut bacteria, like medications, exercise, or stress.

The Bottom Line

Based on this research, eating a Mediterranean-style diet—rich in vegetables, whole grains, nuts, seeds, fish, and olive oil, and low in added sugars and saturated fats—appears to support healthier gut bacteria. This may help with MASLD, though more research is needed to confirm this. Confidence level: Moderate. This is a promising direction, but larger studies are needed before we can say with certainty that diet changes will improve the disease.

This research is most relevant to people diagnosed with MASLD or those at risk for it (people who are overweight or have metabolic syndrome). It’s also relevant to anyone interested in gut health and liver health. However, this study should not replace medical advice from your doctor. People with MASLD should work with their healthcare provider to develop a treatment plan, which may include dietary changes, weight loss, and other interventions.

Changes to gut bacteria can happen relatively quickly—sometimes within weeks of dietary changes—but improvements in liver health typically take longer, usually several months to a year of consistent dietary changes combined with weight loss. Don’t expect overnight results, but staying consistent with healthier eating patterns should show benefits over time.

Want to Apply This Research?

  • Track daily intake of fiber (aim for 25-30 grams), servings of vegetables (aim for 5+ servings), nuts/seeds (1 ounce daily), whole grains (3+ servings), and omega-3 rich foods like fish (2+ servings weekly). Monitor these specific Mediterranean diet components rather than just calories.
  • Set a specific goal like ‘Add one new vegetable to lunch’ or ‘Swap white bread for whole grain bread’ each week. Use the app to log these specific foods and track consistency. Create reminders to eat nuts as snacks and to include fish in meals twice per week.
  • Track Mediterranean diet adherence weekly using a simple score (how many of the key foods did you eat this week?). If possible, work with your doctor to monitor liver health markers (like liver enzymes) every 3-6 months to see if dietary improvements correlate with better liver function over time.

This research shows a connection between diet, gut bacteria, and fatty liver disease, but it does not prove that dietary changes will cure or treat MASLD. This study was small and observational—it cannot establish cause-and-effect. If you have been diagnosed with MASLD or suspect you may have liver disease, consult with your healthcare provider or hepatologist before making significant dietary changes. Do not use this information to self-diagnose or self-treat liver disease. While a Mediterranean-style diet is generally considered healthy, individual nutritional needs vary, and a registered dietitian can provide personalized recommendations based on your specific health situation.