The impact of food additives, artificial sweeteners and domestic hygiene products on the human gut microbiome and its fibre fermentation capacity

Abstract

Purpose: This study investigated the effect of food additives, artificial sweeteners and domestic hygiene products on the gut microbiome and fibre fermentation capacity.

Methods: Faecal samples from 13 healthy volunteers were fermented in batch cultures with food additives (maltodextrin, carboxymethyl cellulose, polysorbate-80, carrageenan-kappa, cinnamaldehyde, sodium benzoate, sodium sulphite, titanium dioxide), sweeteners (aspartame-based sweetener, sucralose, stevia) and domestic hygiene products (toothpaste and dishwashing detergent). Short-chain fatty acid production was measured with gas chromatography. Microbiome composition was characterised with 16S rRNA sequencing and quantitative polymerase chain reaction (qPCR).

Results: Acetic acid increased in the presence of maltodextrin and the aspartame-based sweetener and decreased with dishwashing detergent or sodium sulphite. Propionic acid increased with maltodextrin, aspartame-based sweetener, sodium sulphite and polysorbate-80 and butyrate decreased dramatically with cinnamaldehyde and dishwashing detergent. Branched-chain fatty acids decreased with maltodextrin, aspartame-based sweetener, cinnamaldehyde, sodium benzoate and dishwashing detergent. Microbiome Shannon α-diversity increased with stevia and decreased with dishwashing detergent and cinnamaldehyde. Sucralose, cinnamaldehyde, titanium dioxide, polysorbate-80 and dishwashing detergent shifted microbiome community structure; the effects were most profound with dishwashing detergent (R² = 43.9%, p = 0.008) followed by cinnamaldehyde (R² = 12.8%, p = 0.016). Addition of dishwashing detergent and cinnamaldehyde increased the abundance of operational taxonomic unit (OTUs) belonging to Escherichia/Shigella and Klebsiella and decreased members of Firmicutes, including OTUs of Faecalibacterium and Subdoligranulum. Addition of sucralose and carrageenan-kappa also increased the abundance of Escherichia/Shigella and sucralose, sodium sulphite and polysorbate-80 did likewise to Bilophila. Polysorbate-80 decreased the abundance of OTUs of Faecalibacterium and Subdoligranulum. Similar effects were observed with the concentration of major bacterial groups using qPCR. In addition, maltodextrin, aspartame-based sweetener and sodium benzoate promoted the growth of Bifidobacterium whereas sodium sulphite, carrageenan-kappa, polysorbate-80 and dishwashing detergent had an inhibitory effect.

Conclusions: This study improves understanding of how additives might affect the gut microbiota composition and its fibre metabolic activity with many possible implications for human health.

Keywords: Fermentation capacity; Fibre; Food additives; Gut microbiome; Microbiota.

Fig. 1

Baseline and net production of total and individual short chain fatty acids (μmol/ml) following 24 h batch faecal fermentation of fibre with food additives, artificial sweeteners and domestic hygiene products. Red filling boxplot indicates significant difference (p < 0.05) compared with the CTRL (displayed with grey filling boxplot); 0H baseline, CTRL control, SUCR sucralose, STEV stevia, ASP aspartame based sweetener, MDX maltodextrin, CNMD cinnamaldehyde, SS sodium sulphite, SB sodium benzoate, TIO titanium dioxide, CGN carrageenan-kappa, P80 polysorbate-80, CMC carboxymethyl cellulose, TP toothpaste, DET detergent

Fig. 2

Microbiome α-diversity indices before and following 24 h batch faecal fermentation of fibre with food additives, artificial sweeteners and domestic hygiene products. 0H baseline, CTRL control, SUCR sucralose, STEV stevia, ASP aspartame based sweetener, MDX maltodextrin, CNMD cinnamaldehyde, SS sodium sulphite, SB sodium benzoate, TIO titanium dioxide, CGN carrageenan-kappa, P80 polysorbate-80, CMC carboxymethyl cellulose, TP toothpaste, DET detergent

Fig. 3

Microbiome community structure (β diversity) using the Bray–Curtis dissimilarity index before and following 24 h batch faecal fermentation of fibre with food additives, artificial sweeteners and domestic hygiene products. 0H baseline, CTRL control, SUCR sucralose, STEV stevia, ASP aspartame based sweetener, MDX maltodextrin, CNMD cinnamaldehyde, SS sodium sulphite, SB sodium benzoate, TIO titanium dioxide, CGN carrageenan-kappa, P80 polysorbate-80, CMC carboxymethyl cellulose, TP toothpaste, DET detergent

Fig. 4

Microbiome community structure (β diversity) using the UniFrac unweighted distances before and following 24 h batch faecal fermentation of fibre with food additives, artificial sweeteners and domestic hygiene products. 0H baseline, CTRL control, SUCR sucralose, STEV stevia, ASP aspartame based sweetener, MDX maltodextrin, CNMD cinnamaldehyde, SS sodium sulphite, SB sodium benzoate, TIO titanium dioxide, CGN carrageenan-kappa, P80 polysorbate-80, CMC carboxymethyl cellulose, TP toothpaste, DET detergent

Fig. 5

The effect of food additives, artificial sweeteners and domestic hygiene products on bacterial OTU relative abundance. 0H baseline, CTRL control, SUCR sucralose, STEV stevia, ASP aspartame based sweetener, MDX maltodextrin, CNMD cinnamaldehyde, SS sodium sulphite, SB sodium benzoate, TIO titanium dioxide, CGN carrageenan-kappa, P80 polysorbate-80, CMC carboxymethyl cellulose, TP toothpaste, DET detergent, log2(FC) log2 fold change

Fig. 6

Concentration of total and major bacterial groups (number of 16S rRNA gene copies/ml) before and following 24 h batch faecal fermentation of fibre with food additives, artificial sweeteners and domestic hygiene products. Red filling boxplot indicates significant difference (p < 0.05) compared with the CTRL (displayed with grey filling boxplot); 0H baseline, CTRL control, SUCR sucralose, STEV stevia, ASP aspartame based sweetener, MDX maltodextrin, CNMD cinnamaldehyde, SS sodium sulphite, SB sodium benzoate, TIO titanium dioxide, CGN carrageenan-kappa, P80 polysorbate-80, CMC carboxymethyl cellulose, TP toothpaste, DET detergent

Fig. 7

Heatmap illustrating the summary effects of food additives, artificial sweeteners and domestic hygiene products on net production of total and individual short chain fatty acids and concentration of total and major bacterial groups. 0H baseline, CTRL control, SUCR sucralose, STEV stevia, ASP aspartame based sweetener, MDX maltodextrin, CNMD cinnamaldehyde, SS sodium sulphite, SB sodium benzoate, TIO titanium dioxide, CGN carrageenan-kappa, P80 polysorbate-80, CMC carboxymethyl cellulose, TP toothpaste, DET detergent. Red indicates a decrease and green an increase in the concentration of short chain fatty acids or bacterial groups

Fig. 8

Heatmap illustrating the effects of food additives, artificial sweeteners and domestic hygiene products on mean relative abundance of the top 50 dominant bacterial OTUs across all samples. 0H baseline, CTRL control, SUCR sucralose, STEV stevia, ASP aspartame based sweetener, MDX maltodextrin, CNMD cinnamaldehyde, SS sodium sulphite, SB sodium benzoate, TIO titanium dioxide, CGN carrageenan-kappa, P80 polysorbate-80, CMC carboxymethyl cellulose, TP toothpaste, DET detergent, OTU Operational Taxonomic Unit