Does a Gluten-free Diet Improve Metabolic Syndrome Parameters? A Systematic Review

Abstract

To review scientific evidence on the effects of a gluten-free diet on body composition and improvement of clinical and biochemical parameters of metabolic syndrome. The Preferred Reporting Items for Systematic Reviews and Meta-Analyzes -PRISMA guidelines were followed. A literature search was performed in the PubMed, ScienceDirect, Trip Database, Bireme and Scielo databases, without language restriction, until March 2021. The terms "gluten-free diet", "obesity", "metabolic syndrome", and "weight loss", and Boolean operators (AND/OR) were used. The clinical hypothesis was structured according to the acronym PICOT. Randomized clinical trials with adult and elderly humans without a diagnosis of celiac disease, consuming a gluten-free diet, evaluating associations of the effects of this diet on weight loss and metabolic syndrome components were considered eligible. To assess the risk of bias, the RoB2 was used. A total of 3,198 articles were identified and, after the screening and evaluation of pre-defined eligibility criteria, four studies were included in the qualitative analysis. Weight loss was not associated with a gluten-free diet. However, individuals under a gluten-free diet had lower mean waist circumference, fat percentage (-2.3%) and serum triglyceride levels. The impact of a gluten-free diet on metabolic syndrome parameters is still controversial. In individuals without gluten sensitivity or celiac disease, the consumption of a gluten-free diet appears to provide no nutritional benefit.

Does Gluten Decrease (or Increase) Metabolic Syndrome Risk?

“…This study used one of the largest data sets in the field to elucidate the relationship between GFD and MS parameters. 6 The study highlighted the lack of effects or evidence of this diet in the general population. Furthermore, the GFD seemed not to promote weight gain, and had controversial effects on MS parameters.…”

“…The authors also found a lower intake of fiber and a non-significant weight loss in the GFD group compared with controls. 5 The article by Orange et al, 6 in this issue of the Journal is a secondary analysis of data compiled from four studies fulfilling the inclusion criteria for the qualitative synthesis and systematic review. This study used one of the largest data sets in the field to elucidate the relationship between GFD and MS parameters.…”

“…8 Stefoska-Needham et al, 9 conducted a study only on female individuals and found no effects of gluten restriction. The same results were found by Johnston et al 10 On the other hand, Ehteshami et al, 5 found reduced fasting blood glucose, waist circumference and serum triglyceride concentrations, but only in participants with MS. Orange et al, 6 concluded, in their systematic review, that gluten restriction had no beneficial effects on MS parameters. 5,9,10 and seemed not to promote weight loss in individuals without CD, which often contrasts with marketing and media information.…”