Pro12Ala polymorphism influences body composition changes in severely obese patients consuming extra virgin olive oil: a randomized clinical trial.

Background: Previous intervention studies have reported the association of the Pro12Ala (rs1801282) and -174G > C (rs1800795) polymorphisms with weight loss; however, their results are inconsistent. We aimed to investigate the effect of the Pro12Ala and -174G > C polymorphisms on body weight, body composition and metabolic parameters after a 12-week nutritional intervention with a traditional Brazilian diet and extra virgin olive oil supplementation in severely obese patients.

Methods: A total of 149 severely obese individuals [body mass index (BMI) ≥ 35 kg/m] were randomized into three 12-week nutritional intervention groups - the extra virgin olive oil supplementation (OO) group ( = 50), the traditional Brazilian diet (DieTBra) group ( = 49), and the DieTBra plus extra virgin olive oil supplementation (DieTBra+OO) group (n = 50). Anthropometric measurements, body composition, metabolic parameters, physical activity practise and dietary intake were assessed. The associations were tested using generalized linear models adjusted for confounders.

Results: The Pro12Ala polymorphism influenced body composition changes. Ala carriers in the intervention groups with extra virgin olive oil supplementation had greater reductions in the percentage of body fat (%BF) (OO:  = 0.049, DietBra+OO:  = 0.004) and greater increases in both fat-free mass (FFM) (OO:  = 0.020, DieTBra:  = 0.007) and lean mass (LM) (OO: p = 0.020, DieTBra+OO: p = 0.007) than did ProPro homozygotes. No association was found for the -174G > C polymorphism.

Conclusions: Extra virgin olive oil intake may modulate favourable body composition changes, promoting a decrease in the %BF and increases in the LM and FFM of severely obese individuals, even without weight loss, in the presence of the Ala allele of the Pro12Ala polymorphism.

Trial Registration: Registered under ClinicalTrials.gov Identifier No. NCT02463435.