Our gut microbes are under siege. For starters, they flourish on fiber yet sugar and fat are more likely to be on our plates. Perhaps even more unpalatable is the onslaught of additives, artificial sweeteners and domestic hygiene products—chemicals mostly introduced in the last century.
While food processing can protect from some infectious diseases, the collateral damage to the gut microbiome and host health is only recently being considered.
Exactly how microbes respond is up for debate. Does composition of the microbiota change? Is the fermentation process impacted?
One new study looked at the effect of these common chemicals on gut microbiota composition and its fiber fermentation capacity to produce short-chain fatty acids (SCFAs). The impact of food additives, artificial sweeteners and domestic hygiene products on the human gut microbiome and its fibre fermentation capacity appeared December 2019 in the European Journal of Nutrition.
As the end product of fiber fermentation, SCFAs depend on the host’s diet and microbiome composition. SCFAs are critical bacterial products involved, not only locally in gut health, but also in whole body health. Acetic acid and propionic acid are two and another, butyric acid, has been used as an indicator of healthy status of the microbiome. On the flip side, reduced diversity, low production of SCFA and dysbiosis have been implicated in inflammatory bowel disease, diabetes and obesity.
In this study, Konstantinos Gerasimidis and his team in Glasgow, UK measured the effect of thirteen commonly used food additives, artificial sweeteners, and domestic hygiene products on the healthy gut microbiome composition and its fermentation capacity.
Fecal 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)
- Household products (toothpaste and dishwashing detergent)
Short-chain fatty acid production was measured with gas chromatography while composition was characterised with 16S rRNA sequencing and quantitative polymerase chain reaction (qPCR).
“Six of the additives affected the production of SCFA, five influenced the global microbiome community structure and nine altered the concentration of dominant microbial groups. Only toothpaste, stevia and carboxymethyl cellulose showed no or minimal effects on the broad composition and fermentation capacity of the faecal microbiome.”
The authors added that changes in microbiome composition and SCFA concentrations varied considerably in both the microorganisms or SCFA affected as well as the direction of this effect.
The results imply that the gut microbiome is modifiable in different ways by different additives. Therefore, future study should look at the effects separately.
“As our diet has become more industrialised and is expected to become even more so to sustain food availability, it is important to understand the beneficial or detrimental effect food additives may have on the gut microbiome, and by extension to host health, to guide current and future use.”
Read this interesting paper for more historical evidence on how food additives, artificial sweeteners and household products may influence both rodent and the human gut microbiome and, by extension, the health of the host.
Also, Common Emulsifier Messes with Microbes appeared on the IPA website in 2019.