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J Hepatol. 2019 May 8. pii: S0168-8278(19)30274-0. doi: 10.1016/j.jhep.2019.04.013. [Epub ahead of print]

The beneficial effects of Mediterranean diet over low-fat diet may be mediated by decreasing hepatic fat content.

Author information

1
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine and Sylvan Adams Sports Institute, Tel Aviv University, Israel.
2
Soroka University Medical Center, Beer-Sheva, Israel.
3
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
4
Soroka University Medical Center, Beer-Sheva, Israel; Nuclear Research Center-Negev, Dimona, Israel.
5
Nuclear Research Center-Negev, Dimona, Israel.
6
Department of Medicine, University of Leipzig, Germany.
7
Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard School of Public Health, Boston, MA, USA.
8
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel. Electronic address: irish@bgu.ac.il.

Abstract

BACKGROUND & AIM:

It is unclear if a reduction in hepatic fat content (HFC) is a major mediator of the cardiometabolic benefit of lifestyle intervention, and whether it has prognostic significance beyond the loss of visceral adipose tissue (VAT). In the present sub-study, we hypothesized that HFC loss in response to dietary interventions induces specific beneficial effects independently of VAT changes.

METHODS:

In an 18-month weight-loss trial, 278 participants with abdominal obesity/dyslipidemia were randomized to low-fat (LF) or Mediterranean/low-carbohydrate (MED/LC + 28 g walnuts/day) diets with/without moderate physical activity. HFC and abdominal fat-depots were measured using magnetic resonance imaging at baseline, after 6 (sub-study, n = 158) and 18 months.

RESULTS:

Of 278 participants (mean HFC 10.2% [range: 0.01%-50.4%]), the retention rate was 86.3%. The %HFC substantially decreased after 6 months (-6.6% absolute units [-41% relatively]) and 18 months (-4.0% absolute units [-29% relatively]; p <0.001 vs. baseline). Reductions of HFC were associated with decreases in VAT beyond weight loss. After controlling for VAT loss, decreased %HFC remained independently associated with reductions in serum gamma glutamyltransferase and alanine aminotransferase, circulating chemerin, and glycated hemoglobin (p <0.05). While the reduction in HFC was similar between physical activity groups, MED/LC induced a greater %HFC decrease (p = 0.036) and greater improvements in cardiometabolic risk parameters (p <0.05) than the LF diet, even after controlling for VAT changes. Yet, the greater improvements in cardiometabolic risk parameters induced by MED/LC were all markedly attenuated when controlling for HFC changes.

CONCLUSIONS:

%HFC is substantially reduced by diet-induced moderate weight loss and is more effectively reduced by the MED/LC diet than the LF diet, independently of VAT changes. The beneficial effects of the MED/LC diet on specific cardiometabolic parameters appear to be mediated more by decreases in %HFC than VAT loss.

LAY SUMMARY:

High hepatic fat content is associated with metabolic syndrome, type 2 diabetes mellitus, and coronary heart disease. In the CENTRAL 18-month intervention trial, a Mediterranean/low-carbohydrate diet induced a greater decrease in hepatic fat content than a low-fat diet, conferring beneficial health effects that were beyond the favorable effects of visceral fat loss. ClinicalTrials.gov Identifier: NCT01530724.

KEYWORDS:

Cardiovascular risk; Clinical trial; Diet; Hepatic fat content; Lifestyle; Low carbohydrate; NAFLD; Visceral adipose tissue

PMID:
31075323
DOI:
10.1016/j.jhep.2019.04.013
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