Ad Libitum Mediterranean and Low‐Fat Diets Both Significantly Reduce Hepatic Steatosis: A Randomized Controlled Trial

Abstract

Although diet-induced weight loss is first-line treatment for patients with nonalcoholic fatty liver disease (NAFLD), long-term maintenance is difficult. The optimal diet for improvement in either NAFLD or associated cardiometabolic risk factors, regardless of weight loss, is unknown. We examined the effect of two ad libitum isocaloric diets (Mediterranean [MD] or low fat [LF]) on hepatic steatosis (HS) and cardiometabolic risk factors. Subjects with NAFLD were randomized to a 12-week blinded dietary intervention (MD vs. LF). HS was determined by magnetic resonance spectroscopy (MRS). From a total of 56 subjects enrolled, 49 completed the intervention and 48 were included for analysis. During the intervention, subjects on the MD had significantly higher total and monounsaturated fat, but lower carbohydrate and sodium, intakes compared to LF subjects (P < 0.01). At week 12, HS had reduced significantly in both groups (P < 0.01), and there was no difference in liver fat reduction between groups (P = 0.32), with mean (SD) relative reductions of 25.0% (±25.3%) in LF and 32.4% (±25.5%) in MD. Liver enzymes also improved significantly in both groups. Weight loss was minimal and not different between groups (-1.6 [±2.1] kg in LF vs -2.1 [±2.5] kg in MD; P = 0.52). Within-group improvements in Framingham Risk Score (FRS), total cholesterol, serum triglyceride (TG), and glycated hemoglobin (HbA1c) were observed in the MD (all P < 0.05), but not with the LF diet. Adherence was higher for the MD compared to LF (88% vs. 64%; P = 0.048). Conclusion: Ad libitum low-fat and Mediterranean diets both improve HS to a similar degree.

Ad Libitum Mediterranean or Low‐Fat Diets as Treatments for Nonalcoholic Fatty Liver Disease?

“…No significant differences were observed between, or within groups, in markers of insulin resistance, and measures of both arterial stiffness and liver stiffness (as assessed by FibroScan). (10) Collectively, although some of the observed benefits on liver fat content may have been attributed to a small decrease in abdominal adiposity (visceral fat mass) and an increase in physical activity energy expenditure, we consider that these findings are clinically relevant for patients with NAFLD and provide support for the view that both MD and LFD have the potential to improve HS (by approximately −25% to −30%), even in the absence of significant weight reduction. (10) There are some differences in the benefits conferred by the MD versus the LFD on cardiometabolic risk factors, as illustrated in the linked article.…”

“…Notably, diet adherence was higher with the MD than with the LFD (88% vs. 64%); and among the secondary outcomes, the researchers found that the Framingham Risk Score, plasma lipids, and hemoglobin A1c improved significantly from baseline in the MD group only. No significant differences were observed between, or within groups, in markers of insulin resistance, and measures of both arterial stiffness and liver stiffness (as assessed by FibroScan) …”

“…The findings of Properzi et al add additional information to the body of evidence supporting dietary changes in NAFLD. The researchers show that ad libitum isocaloric MD and low‐fat diets (LFDs) are equally effective in reducing liver fat content (measured by MRS) in NAFLD.…”

“…(10) There are some differences in the benefits conferred by the MD versus the LFD on cardiometabolic risk factors, as illustrated in the linked article. (10) Furthermore, the dietary components (or the absence of some dietary factors) that contribute to the benefit of either diet in NAFLD remain unclear. Nevertheless, in Fig.…”

“…Collectively, although some of the observed benefits on liver fat content may have been attributed to a small decrease in abdominal adiposity (visceral fat mass) and an increase in physical activity energy expenditure, we consider that these findings are clinically relevant for patients with NAFLD and provide support for the view that both MD and LFD have the potential to improve HS (by approximately –25% to –30%), even in the absence of significant weight reduction . There are some differences in the benefits conferred by the MD versus the LFD on cardiometabolic risk factors, as illustrated in the linked article . Furthermore, the dietary components (or the absence of some dietary factors) that contribute to the benefit of either diet in NAFLD remain unclear.…”