From the Journals

Mediterranean diet cut fatty liver risk



Middle-aged and older adults who closely followed a Mediterranean-style diet for 6 years were at significantly lower risk of developing fatty liver disease than others in a large prospective study.

Each 1-standard-deviation rise in Mediterranean-style Diet Score (MDS) correlated with significantly decreased hepatic fat accumulation and a 26% lower odds of new onset fatty liver disease (P = .002). “To our knowledge, ours is the first prospective study to examine the relations of long-term habitual diet to fatty liver,” Jiantao Ma, MBBS, PhD, and his associates wrote in Gastroenterology. “Our findings indicate that improved diet quality may be particularly important for those with high genetic risk for NAFLD.”

The Mediterranean diet emphasizes fruits, vegetables, nuts, legumes, whole grains, and omega-3 fatty acids and minimizes consumption of trans fats and red meat. The diet has been linked with reduced liver fat in a large cross-sectional study and a 6-week randomized trial of patients with nonalcoholic fatty liver disease (NAFLD). In the current study, 1,521 middle-aged and older adults from the Framingham Heart Study self-administered the 126-item Harvard food frequency questionnaire during 2002 through 2005 and 2008 through 2011. Longitudinal changes in two diet scores, the MDS and the Alternative Healthy Eating Index (AHEI), were correlated with hepatic fat based on liver phantom ratio and computed tomography.

Over a median 6 years of follow-up, each 1-standard deviation rise in MDS correlated with a 26% decrease in odds of new-onset fatty liver (95% CI, 10% to 39%; P = .002) and with a significant increase in liver phantom ratio (0.57; 95% confidence interval, 0.27 to 0.86; P less than .001), which signifies lower accumulation of liver fat. Similarly, every 1-standard deviation rise in the AHEI dietary score correlated with a 0.56 rise in liver phantom ratio (95% CI, 0.29 to 0.84; P less than .001) and with a 21% lower odds of incident fatty liver disease (95% CI, 5% to 35%; P = .02).

Individuals whose diets improved the most (those in the highest quartile of dietary score change) over time had about 80% less liver fat accumulate between baseline and follow-up compared with those whose diets worsened the most (those in the lowest quartile of dietary score change). Furthermore, relationship between diet and liver fat remained statistically significant (P = .02) even after accounting for changes in body mass index.

The investigators also studied whether the presence of single nucleotide polymorphisms (SNPs) linked with NAFLD modified dietary effects. High genetic risk for NAFLD did not appear to lead to increased liver fat as long as diet improved or remained stable over time, they found. But when diet worsened over time, high genetic NAFLD risk did correlate with significantly greater accumulation of liver fat (P less than .001).

“Future intervention studies are needed to test the efficacy and efficiency of diet-based approaches for NAFLD prevention as well as to examine mechanisms underlying the association between diet and NAFLD,” the researchers wrote.

The National Heart, Lung and Blood Institute’s Framingham Heart Study provided funding. Affymetrix provided genotyping. The researchers reported having no financial conflicts of interest.

SOURCE: Ma J, et al. Gastroenterology. 2018 Mar 28. doi: 10.1053/j.gastro.2018.03.038

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