COMMENTARY

Mediterranean Diet's Benefits May Extend to Multiple Diseases

William F. Balistreri, MD

Disclosures

November 07, 2018

In This Article

Benefits in Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is associated with visceral obesity, insulin resistance, dyslipidemia, and chronic inflammation, all components of the metabolic syndrome. At present, the recommended management strategy for patients with NAFLD is based on lifestyle interventions—exercise and a balanced (quantitative as well as qualitative) diet.[19] A specific focus of dietary intervention is limiting the intake of calories, saturated/trans fatty acids, and fructose.[20] A 7%-10% reduction in body weight is associated with histologic improvement, resolution of steatosis, necroinflammation, and fibrosis.[21]

The rationale for the Mediterranean diet in NAFLD is sound, because inflammation and oxidative stress are consistent postulated elements of the metabolic syndrome and in the pathogenesis of NAFLD. The Mediterranean diet may have a beneficial effect in patients with NAFLD by exerting antioxidant and anti-inflammatory effects, reducing serum lipids, and favorably altering the gut microbiota.

Two initial, small, short-term randomized trials suggested a potential beneficial effect of the Mediterranean diet on NAFLD.[22,23] In both studies, liver fat content, measured by magnetic resonance spectroscopy, decreased more in the monounsaturated fat recipients (-29% to -39%) than in the high carbohydrate/fiber group (-4% to -7%), despite modest weight loss that was not different between the two diets.

A few recent studies have sought to assess the benefit. In a prospective study, Ma and colleagues[24] examined the association between changes in diet quality and liver fat content. Among the 1521 participants from a Framingham Heart Study cohort, the authors specifically assessed the Mediterranean-style Diet Score (MDS) to determine the diet's impact over 6 years on liver fat accumulation. For each one standard deviation increase in the MDS, less liver fat was noted on CT images and the odds of incident fatty liver decreased by 26%. Increasing diet quality was not only associated with less liver fat accumulation but also reduced the risk for new-onset fatty liver. An improved diet was particularly of benefit for individuals with a high genetic risk for NAFLD.

Sekkarie and colleagues[25] summarized recently published evidence that a high intake of sugar plays a causal role in the development of NAFLD, including several experimental studies that reported a unique effect of fructose consumption on liver fat accumulation. They also cited evidence of the "NAFLD protective effects" of the Mediterranean diet, perhaps through its impact on the microbiome. They suggest that the effect may also be modified by the presence or absence of genetic polymorphisms (nutrigenomics).

Abenavoli and colleagues[26] also cite the growing body of evidence supporting the idea that the Mediterranean diet and accompanying physical activity may prevent and treat patients with NAFLD. 

Properzi and colleagues[27] recently reported that an ad libitum isocaloric Mediterranean diet and a low-fat diet were equally effective in reducing liver fat content in patients with NAFLD. Weight loss was minimal and did not differ between the two groups; there was a small reduction in waist circumference (3-4 cm). Notably, adherence was higher with the Mediterranean diet than with the low-fat diet (88% vs 64%, respectively).

Finally, in a randomized, controlled, single-blind clinical trial, Katsagoni and colleagues[28] found that small changes toward the Mediterranean lifestyle were an effective treatment option for patients with NAFLD.

At present, the Mediterranean diet is recommended for persons with NAFLD by the European Association for the Study of the Liver/European Association for the Study of Diabetes/European Association for the Study of Obesity's clinical practice guidelines.[29] The American Association for the Study of Liver Diseases awaits rigorous, prospective, longer-term trials with histopathologic endpoints before recommendations related to specific macronutrient diets can be made.[30]

Benefits in Fatty Liver Disease

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