Non-alcoholic fatty liver disease (NAFLD) is defined in the literature, as an accumulation of liver fat in individuals, who are not consumers of excessive amounts of alcohol—more than 20 grams per day for women and less than 30 for men.
According to research—"Mediterranean Diet and NAFLD: What We know and Questions That Still Need to be Answered"—which appeared in the December 2019 online issue of the journal Nutrients—"NAFLD encompasses different clinical scenarios, from the simple accumulation of fat in the liver (steatosis), to steatohepatitis (NASH), cirrhosis, and its complications."
The research points out that the presence of liver steatosis globally has hit 25% of the population—with 46% here in the United States. Liver steatosis represents a reversible condition caused by an accumulation of triglyceride fat in liver cells.
The Merckmanual.com says that NASH is defined as the presence of fat leading to lipo-toxicity and inflammatory damage to hepatocytes (liver cells).
Since there no approved drug treatment methods to address the global impact of NAFLD and its manifestations, addressing systemic and visceral (fat in midsection) obesity and the associated inflammation is an appropriate place to start.
The Mediterranean Diet (MD)—a plant-based eating plan with a high ratio of mono-unsaturated fatty acids (MUFA), representing 30-40% of the daily caloric intake—is rich in olive oil, nuts, vegetables, whole grains, legumes, fish (high sources of omega-3 fatty acids) and other seafood, while low in meat and dairy products, and moderate alcohol consumption (mainly rede wine)—all anti-inflammatory in nature.
From a dietary pyramid perspective, the MD breaks out as follows: protein (legumes, fish & meat) constitute 25%, vegetables & fruits 50%, grains, rice, and pasta 25%—with 1 glass of red wine and 1-2 servings of olive oil.
The Italian study investigators comment that, "a diet (like the MD) rich in omega-3-fatty acids has been shown to be protective against fatty liver as it prevents hepatic fat accumulation and reduces hepatic steatosis. An additional benefit of the MD on fatty liver disease is related to its low content of refined sugars, fructose, and high content of complex carbohydrates and fibers."
Surprisingly, the researchers note that, "the MD consents to a moderate amount of alcoholic units per day. Although there is a lack of studies with convincing evidence to support the benefits versus harms of ethanol intake, light alcohol intake seems safe in NAFLD non-cirrhotic patients."
A recent retrospective study the Italians cite on the effects of alcohol consumption on survival in NAFLD-patients, "reported that drinking 0.5-1.5 drinks per day decreases the risk of overall mortality by 41%." I personally find that research suspect.
The MD is rich in high-fiber whole grains, which may be beneficial in NAFLD patients, since they have less energy density and induce more satiety (hunger satisfaction) than refined carbohydrates. The whole grains also modulate gut microbiota through its prebiotic (food for the healthy gut bacteria), which may play a role in the pathogenesis of NAFLD and its progression.
The Italians conclude by commenting that, "MD has recently been suggested as the diet of choice for NAFLD treatment, but the evidence behind this recommendation is very low, as most of the studies that have addressed this issue included few patients, differed in the inclusion/exclusion criteria, the methods by which steatosis was measured, and in the measurement of outcomes."
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