The consumption of flavonoid-rich foods was associated with a reduced risk of NAFLD among middle-aged adults

By Dr. Chinta SidharthanReviewed by Lily Ramsey, LLMSep 30 2024

Study reveals that a flavonoid-rich diet, especially with apples and tea, may reduce liver fat and inflammation, lowering the risk of NAFLD.

Study: A Flavonoid-Rich Diet is Associated with Lower Risk and Improved Imaging Biomarkers of NAFLD: A Prospective Cohort Study. Image Credit: marilyn barbone/Shutterstock.com

In a recent study published in The American Journal of Clinical Nutrition, researchers conducted a population-based prospective cohort analysis to determine whether a diet rich in flavonoids had a positive impact on non-alcoholic fatty liver disease (NAFLD) and examined the association between flavonoid-diet indices and a set of NAFLD imaging-derived biomarkers consisting of liver steatosis and liver fat.

Background

In the past few decades, the global prevalence of NAFLD has increased by 50%, with the accumulation of fat in the liver constituting up to 5% of the liver tissue without alcohol consumption.

NAFLD can also progress to more serious conditions involving inflammation, such as non-alcoholic steatohepatitis or NASH, fibrosis or scarring of the liver, and eventual liver failure.

Factors such as a sedentary lifestyle and obesity influence the risk of NAFLD, highlighting the importance of weight loss, cardiovascular health, and dietary and lifestyle choices for the prevention or treatment of the disease.

Plant-based diets that are rich in vegetables, fruits, and whole grains are highly beneficial for metabolic and cardiovascular health. These diets are rich in flavonoids, which are bioactive compounds found in apples, berries, tea, red wine, and cocoa.

These compounds come in different forms and are linked to a decrease in the risk of type 2 diabetes and cardiovascular disease. Studies have also shown that following a Mediterranean diet could lower the risk of NAFLD.

About the study

In the present study, the researchers used a prospective cohort from the United Kingdom (U.K.) Biobank to explore how diets rich in flavonoids impact the accumulation of fat in the liver and examine its association with imaging-derived NAFLD biomarkers.

The U.K. Biobank contains over 500,000 participants and provided baseline data on health, sociodemographic characteristics, and dietary habits for the study. Detailed dietary data was obtained between 2009 and 2012 using five different 24-hour dietary recall questionnaires.

Additional follow-up data consisted of body composition measurements based on magnetic resonance imaging (MRI) scans collected from 2014 till the diagnosis or end of the study.

The first part of the study examined the association between flavonoid intake, measured using a Flavodiet Score, and the incidence of NAFLD. The Flavodiet Score represented the cumulative daily portions of foods rich in flavonoids, such as tea, berries, apples, dark chocolate, and red wine.

The second part of the study examined how the intake of flavonoids in the diet correlated with MRI imaging-derived NAFLD biomarkers such as liver steatosis and liver fat.

Hospital inpatient records were used to identify NAFLD cases, and the patients were contacted for follow-ups after their last dietary assessment. Proton density fat fraction through the MRI scans was used to measure liver fat.

Two models were used for the analysis, one where the analysis was adjusted for age and sex, and the other where factors such as smoking status, physical activity levels, body mass index, alcohol intake, and education levels were incorporated as covariates.

Additionally, sensitivity analyses were conducted for tea and red wine consumption to rule out bias from increased consumption of tea or alcohol.

Results

The study identified 1,081 cases of NAFLD over a 10-year follow-up period and found that patients who had a high flavonoid dietary score were 19% less likely to develop NAFLD compared to those who had a low Flavodiet Score.

Furthermore, increased consumption of tea and apples was linked to 14% and 22% lower risk of NAFLD, respectively. However, no significant associations were found between other flavonoid-rich foods such as berries or red wine, and the risk of NAFLD.

Participants in the highest percentile of the Flavodiet Score also showed significantly lower levels of liver inflammation and liver fat percentages, indicating that flavonoid-rich diets were associated with liver health biomarkers.

The corrected T1 or cT1, which is an MRI-based quantitative metric for assessing inflammation and fibrosis in the liver, showed an inverse relationship with tea intake.

Other foods such as dark chocolate and sweet peppers were also linked to lower levels of fat and inflammation in the liver, while grapes and onions were associated with higher levels of liver fat.

The flavonoid anthocyanin showed contrasting associations with NAFLD, with higher anthocyanin intake being linked to higher levels of liver fat and low cT1 values, indicating a complex relationship that requires to be explored further.

Conclusions

Overall, the findings suggested that a diet rich in flavonoids, especially in the form of apples or tea, could potentially protect against NAFLD, and lower the levels of inflammation and fat in the liver.

While foods such as dark chocolate, sweet peppers, apples, and tea have been linked to low levels of liver fat, others such as grapes and onions were found to be associated with higher liver fat accumulation, highlighting the complex impact of diet on liver health.