Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the United States. According to the National Institutes of Diabetes and Digestive and Kidney Diseases, approximately 30 to 40 percent of American adults have the condition, as do almost 10 percent of children between ages of 2 to 19 years old.

There are a number of reasons for the increase in incidence of the disease and for being at risk – obesity, type 2 diabetes, and other related conditions, often clustered together as one condition called metabolic syndrome. Extra fat deposits in the liver threaten the liver’s ability to work properly. When that happens, the body can’t metabolize drugs properly, filter blood, detoxify, or properly digest food because of decreased bile production. Fortunately, the liver is also resilient. Fat deposits can diminish on their own, but lifestyle and nutrient interventions would go a long way to setting things right.

This study focused on the ability of olive oil and the Mediterranean diet to improve the liver’s health status. Participants either followed a Mediterranean diet with supplemental olive oil, the same diet supplemented with nuts (also a source of healthy fats, fiber, and protein), or a controlled diet that reduced overall fat intake.

By the end of the three-year study period, those in the Mediterranean diet with olive oil saw the lowest remaining levels of fat in the liver. Bear in mind that the caloric intake in the Mediterranean diet groups wasn’t controlled and no recommendations to lose weight or boost exercise were part of the program. From this, it appears that olive oil has a great deal of influence over the health of the liver. And, interestingly, it fared better in results than the controlled, reduced fat diet plan.

For many people, it may seem counterintuitive to add another fat to a diet. But pairing additional olive oil with a Mediterranean diet – already known to have benefits for the heart and waistline – may be the most enjoyable way to stay healthy.

Abstract:

Pintó X, Fanlo-Maresma M, Corbella E, et al. A Mediterranean Diet Rich in Extra-Virgin Olive Oil Is Associated with a Reduced Prevalence of Nonalcoholic Fatty Liver Disease in Older Individuals at High Cardiovascular Risk. J Nutr. 2019 Jul 23. pii: nxz147.

BACKGROUND: Adherence to a Mediterranean diet (MedDiet) is thought to reduce liver steatosis.

OBJECTIVES: To explore the associations with liver steatosis of 3 different diets: a MedDiet + extra-virgin olive oil (EVOO), MedDiet + nuts, or a control diet.

METHODS: This was a subgroup analysis nested within a multicenter, randomized, parallel-group clinical trial, PREvención con DIeta MEDiterránea (PREDIMED trial: ISRCTN35739639), aimed at assessing the effect of a MedDiet on the primary prevention of cardiovascular disease. One hundred men and women (mean age: 64 ± 6 y), at high cardiovascular risk (62% with type 2 diabetes) from the Bellvitge-PREDIMED center were randomly assigned to a MedDiet supplemented with EVOO, a MedDiet supplemented with mixed nuts, or a control diet (advice to reduce all dietary fat). No recommendations to lose weight or increase physical activity were given. Main measurements were the percentage of liver fat and the diagnosis of steatosis, which were determined by NMR imaging. The association of diet with liver fat content was analyzed by bivariate analysis after a median follow-up of 3 y.

RESULTS: Baseline adiposity and cardiometabolic risk factors were similar among the 3 treatment arms. At 3 y after the intervention hepatic steatosis was present in 3 (8.8%), 12 (33.3%), and 10 (33.3%) of the participants in the MedDiet + EVOO, MedDiet + nuts, and control diet groups, respectively (P = 0.027). Respective mean values of liver fat content were 1.2%, 2.7%, and 4.1% (P = 0.07). A tendency toward significance was observed for the MedDiet + EVOO group compared with the control group. Median values of urinary 12(S)-hydroxyeicosatetraenoic acid/creatinine concentrations were significantly (P = 0.001) lower in the MedDiet + EVOO (2.3 ng/mg) than in the MedDiet + nuts (5.0 ng/mg) and control (3.9 ng/mg) groups. No differences in adiposity or glycemic control changes were seen between groups.

CONCLUSIONS: An energy-unrestricted MedDiet supplemented with EVOO, a food with potent antioxidant and anti-inflammatory properties, is associated with a reduced prevalence of hepatic steatosis in older individuals at high cardiovascular risk.