A modified Mediterranean diet is associated with the greatest reduction in alanine aminotransferase levels in obese type 2 diabetes patients: results of a quasi-randomised controlled trial

Abstract

Aim The aim of the study was to compare the effect of different dietary interventions on alanine aminotransferase (ALT) in obese patients with diabetes. Methods A post hoc analysis of an open label, parallel design, quasi-randomised (allocation by alternation), controlled trial, conducted in Israel. Obese patients with diabetes (n=259), treated in the community, were centrally allocated to one of three diets: (1) the 2003 recommended American Diabetes Association diet (ADA): 50-55% carbohydrate, 30% fat and 20% protein, n=85; (2) a low glycaemic index (LGI) diet: 50-55% LGI carbohydrate, 30% fat, 15-20% protein, n = 89; or (3) a modified Mediterranean diet (MMD): 35% LGI carbohydrate, 45% fat that was high in monounsaturated fat, 15-20% protein, n=85. ALT was measured at 6 and 12 months. Results ALT levels decreased in all arms; however, the MMD was associated with the lowest ALT levels at month 6 (n=201: ADA n=64, LGI n=73, MMD n=64) and month 12 of follow-up (n=179). At 12 months mean ALT levels were 19.8±1.4 U/l in the ADA diet arm (n=54), 18.0±1.5 U/l in the LGI diet arm (n=64) and 14.4±1.7 in the MMD arm (n=61, p<0.001). Evidence for an effect of diet on ALT levels persisted when controlling for post-randomisation changes in waist to hip ratio, BMI, homeostasis model assessment (HOMA) or triacylglycerol. Conclusions A Mediterranean diet may have a beneficial effect on liver steatosis in obese patients with diabetes. Results of trials assessing the effect of dietary composition on clinical outcomes should be awaited before a decisive conclusion can be reached. In addition to clinical outcomes, such studies should address the issue of primary prevention of steatosis in high-risk and healthy individuals.

Optimal dietary approaches for prevention of type 2 diabetes: a life-course perspective

“…In a 6 month intervention trial, a low-carbohydrate ketogenic diet resulted in a better lipid profile and clearly improved steatosis and inflammation in liver biopsies in comparison to a conventional low-fat diet [66]. Finally, a post hoc analysis of a 1 year weight loss trial conducted in middle-aged obese Israeli patients with type 2 diabetes indicated that a Mediterranean diet reduced alanine aminotransferase levels (a biomarker for NAFLD) to a larger extent than a conventional low-fat diet [67].…”

Mediterranean diet in type 2 diabetes

“…Some food groups (vegetables, legumes, fruit and nuts, cereals, olive oil, wine and fish) are characteristic of the Mediterranean diet and have been frequently used in conjunction with non-characteristic elements (meat, dairy), to give a modified functional definition [2]. The provision of information on food groups would clarify how comparable the study by Fraser et al [1] is to other investigations of this subject.…”

“…To the Editor: We read with great interest the article by Fraser et al [1], which reported that patients randomised to receive a modified Mediterranean diet (MMD) showed greater reductions in alanine aminotransferase levels at 6 and 12 months compared with those who received the 2003 American Diabetes Association diet or the low glycaemic index diet.…”

“…Macronutrient intakes (assessed using a food frequency questionnaire) for the three different diet groups at 6 months after randomisation are shown in Table 2 of the paper [1]; however, no data are provided on the consumption of different food groups. This information is needed to appraise the practical implications of the results.…”

“…virgin olive oil, fruit and vegetables, red wine), it may be speculated that differences in levels of these constituents across the three diets, rather than the total amount of carbohydrate or fat, are responsible for the greater reductions in the alanine aminotransferase levels observed in the MMD group at 6 and 12 months. In addition to the beneficial effects of a Mediterranean diet demonstrated in the PREDIMED (Prevención con Dieta Mediterránea) trial [5], mentioned in the paper by Fraser et al [1], a large Spanish prospective dynamic cohort (n=13,380), included in the SUN (Seguimiento Universidad de Navarra) study, has recently shown that a Mediterranean-type diet is able to substantially reduce the risk of type 2 diabetes [6] and the metabolic syndrome [7]. It is therefore possible that the evidence provided by Fraser et al [1] suggesting that a Mediterranean diet can offer substantial benefit on liver steatosis is connected to these reported reductions in risk [6,7].…”