Researchers focused on what’s known as non-alcoholic fatty liver disease (NAFDL), which is usually associated with obesity and certain eating habits. While dietary changes are recommended to treat this type of liver disease, research to date hasn’t clearly demonstrated whether these changes can work for prevention.
For the current study, researchers examined data from dietary questionnaires and liver fat scans for 1,521 people enrolled in the long-running Framingham Heart Study. Participants did the questionnaires and scans twice, at least three to four years apart.
During the study, people with above-average increases in adherence to a healthy Mediterranean diet rich in whole grains, fish, lean protein, veggies and olive oil were at least 26 per cent less likely to develop fatty liver than individuals with average increases in adherence, the study found.
Above-average increases in sticking to another liver-friendly diet, the so-called Alternative Healthy Eating Index, were associated with at least 21 per cent lower odds of developing fatty liver, researchers report in Gastroenterology.
People with a high genetic risk for fatty liver disease whose diet scores decreased during the study period accumulated more fat in their livers. But even with a high genetic risk, fat accumulation didn’t increase if people kept their diets the same or improved them.
“Our findings demonstrate that increasing diet quality is associated with less liver fat accumulation and reduced risk for new-onset fatty liver, particularly in individuals with a high genetic risk for NAFLD,” said senior study author Dr Daniel Levy, director of the Framingham Heart Study and a researcher at the National Institutes of Health in Bethesda, Maryland.
Participants who had improved diet quality scores consumed more fruit, vegetables, and whole grains, which have high amounts of water and fibre.
“We speculated that these foods may decrease energy intake by affecting satiety and improve weight control and therefore reduce liver fat,” Levy said.
“It is also possible that fibre intake may affect gut bacteria and subsequently have impact on liver fat.”
Both diets in the study also limit intake of red meat that can lead to liver fat, and encourage consumption of foods like nuts, which may help reduce liver fat accumulation, Levy added.
Most people have a little bit of fat in their liver. Fatty liver disease can occur when more than 5 per cent of the liver by weight is made up of fat. Excessive drinking can damage the liver and cause fat to accumulate, a condition known as alcoholic fatty liver, but even when people don’t drink much, they can still develop non-alcoholic fatty liver disease.
The study wasn’t a controlled experiment designed to prove whether or how diet changes might impact the risk of developing fatty liver. Researchers also relied on questionnaires to assess participants” diets, which can be unreliable, and they lacked data on non-dietary causes of liver fat accumulation including certain medications and viral infections.
Even so, the findings add to the evidence suggesting that healthy eating habits can minimise the risk of fatty liver disease, even when people have a genetic risk for this condition, said Shira Zelber-Sagi, a researcher at the University of Haifa in Israel who wasn’t involved in the study.
“Genetics is not a destiny,” Zelber-Sagi said by email. “The patients have the power to improve their liver health by themselves in many cases of NAFLD.”