Do wine sulphites affect gut microbiota? An in vitro study of their digestion in the gastrointestinal tract

Abstract

“Sulphites” and mainly sulphur dioxide (SO₂) is by far the most widely used additive (E-220/INS 220) in winemaking and likely the most difficult to replace. The well-known antioxidant, antioxidasic and antimicrobial properties of SO₂ make this molecule a practically essential tool, not only in winemaking, but also in the production of other food products. The current trend in winemaking is the reduction of this unfriendly additive due to its negative effects on health and environmental. In particular, it could cause headaches and intolerance/allergic reactions in sensitive individuals. Wine is considered one of the major contributors of exposure of SO₂ in the adult population, when this beverage is included in the diet. The European Union establishes that the limits for total SO₂ content may not exceed 200 mg/L for red wines with a sugar content higher than 5 g/L, whereas the threshold for an adverse reaction varies between 5 and 200 mg/L SO₂. The gut microbiome is now considered a therapeutic target for many pathologies and for general health status. Recent research has highlighted the potential of wine to modulate the gut microbiome, mainly attributed to its phenolic content and diversity. To our knowledge, very few studies have addressed the effects of sulphites on the gut microbiota, which could be mediated by the dietary matrix. Therefore, the novel question that arises is whether the presence of sulphites in wine may also affect our gut microbiome. To disclose this matter, we have designed an in vitro study based on the simulated gastrointestinal digestion in the simgi® simulator of the following comparative wines: a) synthetic wine, b) synthetic wine fortified with SO₂ (200 mg/L), c) young red wine (2,8 mg/L of free SO₂), and d) young red wine fortified with SO₂ (200 mg/L). The following analyses were performed in the wines after intestinal and colonic (0, 6, 24, and 48h) digestions: free and bound SO₂ by the PAUL-Rankine method (OIV-MA-AS323-04A), microbial plate counting, qPCR and 16S rDNA sequencing, microbial ammonium production, short chain fatty acids (SCFA) by SMPE-GCMS, and phenolic metabolites by UPLC-ESI-MSMS. The results indicate that, at least to some extent, the addition of sulphites to wine may have an impact on the gut microbiome, although this may be dependent on the composition of the wine, especially with regard to its phenolic content.

Acknowledgements: MICIN (PID2019-108851RB-C21 Project). The authors would also like to thank R. de Diego for sound technical assistance.