Rapeseed and Soy Lecithin As Food Additives Vectors of α-Linolenic Acid: Impacts on High-Fat Induced Adiposity, Inflammation and Gut Microbiota in Mice

Abstract Objectives Dietary synthetic emulsifiers have recently been shown to promote metabolic syndrome and alter gut microbiota. The effects of natural emulsifiers, such as vegetable lecithin, remain, however, poorly described. Our objective was to evaluate, in mice, the impact of soy and rapeseed lecithin, both rich in essential α-linolenic acid (ALA), when incorporated in high-fat (HF) Western diets on the bioavailability of ALA, as well as on HF-induced adiposity, inflammation and gut microbiota. Methods For 13 weeks, male Swiss mice (n = 72) were fed either a standard Chow diet, a control semi-synthetic HF-diet (25 wt% lipids) poor in ALA (HFC), or different ALA-enriched (4.7% of total fatty acids) HF-diets containing 0% lecithin (HFA-L0), a nutritional dose of soy or rapeseed lecithin (10 wt% of lipids; HFA-SL10, HFA-RL10), or a 20 wt% supplemental dose of RL (HFA-RL20). Histomorphology of the epididymal adipose tissue (EAT) was analysed; hepatic lipid composition was determined by GC-FID, gene expression by RT-PCR, and faecal microbiota composition by 16S sequencing. Results Within ALA-rich HF diets, the hepatic bioavailability of ALA was similar whether ALA was vectorised as lecithin (HFA-RL10, HFA-RL20, HFA-SL10) or as oil only (HFA-L0) (yet, all higher than HFC). Similarly to HFC, HFA-SL10 and HFA-RL20, but not HFA-RL10, increased body weight gain (P < 0.001), visceral adiposity (P < 0.001) and adipocyte hypertrophy (P < 0.05), compared to Chow. The addition of lecithin in HF-diets, regardless of origin or dose, cancelled the anti-inflammatory effect of ALA observed in HFA-L0 on the expression of genes involved in macrophage infiltration in the EAT (e.g., Tnfα, Cd11c). Only HFA-RL10 increased gut microbiota α-diversity compared to HFC (P < 0.05), and altered the abundance of several gut bacterial groups, such as Lachnospiraceae and Desulfovibrionaceae. Conclusions Although the incorporation of neither soy nor rapeseed lecithin in HF-diets improved ALA hepatic bioavailability, the two lecithins exerted differential metabolic effects in mice. At a nutritional dose, rapeseed lecithin, unlike soy lecithin, did not significantly enhance visceral adiposity comparatively to a Chow diet, and increased gut bacterial diversity. Rapeseed lecithin may therefore be considered as a promising food ingredient. Funding Sources ANRT CIFRE PhD grant (UMT ACTIA BALI).