Rangel-Zuniga’s recent research publication,1 which describes proteomic changes resulting from dietary lipids, may be valuable to anyone with a scientific – or even personal – interest in metabolic syndrome.

Rangel-Zunigal and his research team wanted to determine whether diets that vary in the quantity and quality of fatty acids would influence the proteome (the set of proteins that are expressed) of subjects with metabolic syndrome. To do this, they placed 24 people with metabolic syndrome on one of four diets:

  • High saturated fatty acid (HSFA);
  • High monounsaturated fatty acid (HMUFA);
  • Low fat, high complex carbohydrate diet supplemented by placebo (LFHCC); and
  • Low fat, high complex carbohydrate diet supplemented with long chain (LC) n-3 polyunsaturated fatty acid (PUFA) (LFHCC n-3).

Gross Physical Measures

Research team members measured participants’ body mass index (BMI), waist circumference, blood lipids, glucose and insulin at the beginning and end of the 12-week study. The team did not observe any significant changes to baseline or post-intervention physical measures, nor were any significant changes noted in fasting lipid levels or other metabolic parameters.

Molecular Alterations

The researchers used peripheral blood mononuclear cells (PMBC) to analyze changes to the proteome. PBMC is a model system that Rangel-Zunigal’s lab has used in the past, as the cells are easy to isolate from human blood and can be used as an in vivo model to study biological responses. The team took samples from participants at baseline and after 12 weeks on the diets. Using a combination of 2D polyacrylamide gel electrophoresis (2D-PAGE) coupled with mass spectrometry they identified proteins that showed altered expression levels.

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The researchers recognized a total of 56 proteins that were differentially expressed in either the nuclear or cytoplasmic fractions of PBMCs of the participants who were on one of the four diets. They used informatics software to investigate functional relationships between the differentially expressed proteins. Each of the four diets produced distinct sets of differentially expressed proteins and unique network diagrams. Few proteins identified were common to more than one diet.

In their discussion, the researchers’ review how the differentially expressed proteins may be involved in pathways related to inflammation, oxidative stress, endoplasmic reticular stress and DNA repair. They conclude that long-term consumption of the HSFA diet, as compared to the other three, may increase risk factors associated with metabolic syndrome such as inflammation and oxidative stress, leading to DNA damage. More investigation regarding altered proteins and the pathways they affect is required to confirm this conclusion.

The most important part of this study is that clear proteomic alterations do occur in response to dietary adjustments. These molecular changes occurred in the absence of significant changes between the participants’ pre- and post-diet BMI, waist circumference, lipids and glucose measurements. Because this work is part of an ongoing project, it will be interesting to learn from future papers how soon proteomic changes can be detected after a diet is started, and how long the changes persist after diet discontinuation.

  1. Rangel-Zúñiga OA, Camargo A, Marin C, et al. Proteome from patients with metabolic syndrome is regulated by quantity and quality of dietary lipids. BMC Genomics 2015, 16:509  doi:10.1186/s12864-015-1725-8.