Researchers looked at 25 studies involving 1,689 people with non-alcoholic fatty liver disease (NAFLD), a condition where fat builds up in the liver. They found that flavonoids—natural compounds found in plants—may help improve several markers of liver health. When people took flavonoid supplements, their liver enzyme levels decreased, cholesterol improved, and their bodies became better at handling blood sugar. However, the supplements didn’t significantly reduce liver scarring or inflammation. While these results are promising, scientists say more long-term research is needed to confirm these benefits and understand how flavonoids work best.

The Quick Take

  • What they studied: Whether natural plant compounds called flavonoids can help people with fatty liver disease by improving liver function and overall health markers.
  • Who participated: 1,689 people across 25 different studies who had been diagnosed with non-alcoholic fatty liver disease (NAFLD). This is a condition where too much fat accumulates in the liver without being caused by alcohol.
  • Key finding: Flavonoid supplements significantly improved several important health markers: liver enzyme levels dropped by meaningful amounts, cholesterol levels improved, blood sugar control got better, and the liver’s ability to process insulin improved. However, the supplements didn’t significantly reduce scarring or inflammation in the liver.
  • What it means for you: If you have fatty liver disease, flavonoid-rich foods or supplements may help improve some aspects of your liver health, particularly liver function and blood sugar control. However, this shouldn’t replace medical treatment, and you should talk to your doctor before starting any supplement. Results may vary from person to person, and more research is needed to understand long-term effects.

The Research Details

This was a meta-analysis, which means researchers combined data from 25 different high-quality studies (called randomized controlled trials) to get a bigger picture of how flavonoids affect fatty liver disease. They searched five major medical databases for all studies published through December 2024 that tested flavonoid supplements in people with NAFLD.

The researchers followed strict guidelines called the Cochrane Handbook and PRISMA standards to make sure they included the right studies and analyzed the data correctly. They looked at studies that measured different health markers: liver enzyme levels (which show how well your liver is working), cholesterol and triglyceride levels, blood sugar control, body measurements, and liver scarring.

By combining results from all these studies, the researchers could see patterns that might not be obvious in any single study. This approach gives us a more reliable picture of whether flavonoids actually help people with fatty liver disease.

This research approach is important because fatty liver disease is very common and there aren’t many proven treatments besides lifestyle changes. By combining results from multiple studies, researchers can see if flavonoids are truly helpful or if earlier positive results were just flukes. This meta-analysis approach is considered one of the strongest types of evidence in medical science.

This study followed strict international guidelines for combining research, which makes it reliable. The researchers included 25 studies with a total of 1,689 participants, which is a reasonably large group. However, the quality of individual studies can vary, and the researchers didn’t find strong evidence for some outcomes. The fact that they were transparent about what worked and what didn’t suggests honest reporting.

What the Results Show

Flavonoid supplements showed clear benefits for several liver health markers. Liver enzyme levels (AST, ALT, and ALP) all decreased significantly, which means the liver was working better and experiencing less damage. Total cholesterol levels dropped, and triglycerides (a type of fat in the blood) also decreased. People’s fasting blood sugar levels improved, and their bodies became better at using insulin to control blood sugar—this is measured by something called QUICKI, which improved in the flavonoid groups.

Body mass index (BMI), which measures whether someone is at a healthy weight, also improved with flavonoid supplements. These improvements suggest that flavonoids may help reduce the amount of fat in the liver and improve overall metabolic health.

However, the research showed that flavonoids didn’t significantly help with some other important markers. Liver scarring (fibrosis) didn’t improve much, and inflammation markers didn’t change significantly. Weight loss wasn’t greater in the flavonoid groups compared to control groups, and other body measurements like waist circumference didn’t show major improvements.

Interestingly, while total cholesterol improved, the breakdown of cholesterol types (LDL and HDL) didn’t change much. This suggests flavonoids may work through different pathways than some other treatments. The fact that insulin sensitivity improved without major weight loss suggests flavonoids may help your body use insulin more efficiently, independent of weight changes. This is important because insulin resistance is a key problem in fatty liver disease.

This research builds on earlier studies that suggested flavonoids had anti-inflammatory and antioxidant properties. This meta-analysis confirms that some of those benefits are real, particularly for liver function and blood sugar control. However, it also shows that flavonoids may not be as powerful for reducing liver scarring as some earlier research suggested. This is a more realistic picture than previous individual studies might have shown.

The studies included had different designs and used different types and doses of flavonoids, which makes it harder to know the best way to use them. Most studies were relatively short-term, so we don’t know if benefits last over months or years. The research didn’t look at whether flavonoids work better when combined with other treatments or lifestyle changes. Some studies were small, and not all studies measured the same health markers, which limits what conclusions can be drawn. Finally, the studies didn’t thoroughly examine side effects or safety concerns with long-term use.

The Bottom Line

If you have fatty liver disease, eating more flavonoid-rich foods (like berries, dark chocolate, tea, and colorful vegetables) is a safe, evidence-based approach with moderate confidence. Flavonoid supplements may help improve liver function and blood sugar control, but the evidence is moderate, not strong. These should be used alongside, not instead of, lifestyle changes like exercise and healthy eating. Always talk to your doctor before starting supplements, especially if you take other medications.

People diagnosed with non-alcoholic fatty liver disease should pay attention to this research. It’s particularly relevant for those struggling with blood sugar control or high cholesterol. However, this research is less relevant for people with alcoholic liver disease or those with advanced liver scarring. If you’re pregnant, nursing, or taking blood-thinning medications, check with your doctor before using flavonoid supplements.

Based on the studies reviewed, most people showed improvements in liver enzymes and blood sugar within 8-12 weeks of taking flavonoids. However, more dramatic changes in liver scarring or weight loss would likely take several months. You shouldn’t expect overnight results—think of flavonoids as a supporting tool rather than a quick fix.

Want to Apply This Research?

  • Track your intake of flavonoid-rich foods daily (berries, dark leafy greens, tea, dark chocolate, citrus fruits) and log weekly measurements of energy levels and digestion. Set a goal to consume at least 2-3 servings of flavonoid-rich foods daily.
  • Add one flavonoid-rich food to each meal: blueberries at breakfast, green tea as a snack, and colorful vegetables at dinner. If taking supplements, set daily reminders and track consistency. Also log any lifestyle changes like exercise or diet modifications that happen alongside flavonoid intake.
  • Monthly check-ins to assess energy levels, digestion, and overall wellbeing. If possible, work with your doctor to track liver enzyme levels (AST, ALT) through blood tests every 3 months to see if flavonoids are helping. Keep notes on any side effects or changes in how you feel.

This research summary is for educational purposes only and should not replace professional medical advice. Fatty liver disease is a serious condition that requires medical supervision. Before starting any flavonoid supplements, consult with your doctor or hepatologist, especially if you have advanced liver disease, take medications, are pregnant, or nursing. While flavonoids show promise, they are not a substitute for proven treatments like weight loss, exercise, and dietary changes. Some flavonoid supplements may interact with blood-thinning medications or other drugs. Always inform your healthcare provider about any supplements you’re considering.