My eye caught a news story today Common food additive may impact gut bacteria, increase anxiety.
Earlier studies have shown that emulsifiers can alter the microbiome of mice, causing low-grade inflammation and increasing the risk of obesity and metabolic disorders.
A study in humans concluded that gut bacteria “can be directly impacted by these commonly used food additives, in a manner that subsequently drives intestinal inflammation.”
The scientists showed that the emulsifiers did impact gut bacteria, but in different ways for male and female mice. They also showed that the changes in behavior were different between the sexes.
Specifically, they saw an increase in anxious behavior, particularly in male mice. In female mice, there was a reduction in social behavior.
A common one is polysorbate 80, which I have a page on the bacteria that it is known to change, here. It is often found in ice cream and cottage cheese. It is also in some vaccines.
Another one, cited above is carboxymethylcellulose (CMC)
- The Role of Carrageenan and Carboxymethylcellulose in the Development of Intestinal Inflammation.
- Dietary emulsifiers directly alter human microbiota composition and gene expression ex vivo potentiating intestinal inflammation 
- Acute Exposure to Commonly Ingested Emulsifiers Alters Intestinal Mucus Structure and Transport Properties.
- Dietary Emulsifier-Induced Low-Grade Inflammation Promotes Colon Carcinogenesis. 
- Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome.
- Nonstarch polysaccharides modulate bacterial microbiota, pathways for butyrate production, and abundance of pathogenic Escherichia coli in the pig gastrointestinal tract.
- Bacterial overgrowth and inflammation of small intestine after carboxymethylcellulose ingestion in genetically susceptible mice.
Other emulsifers used in the US include :
- lecithin [phosphatidylcholine (PC)] ,
- mono- and diglycerides (MDGs),
- stearoyl lactylates,
- sucrose esters, and
- polyglycerol polyricinoleate.
For lecithin, we read:
Dietary carnitine (present predominately in red meat) and lecithin (phosphatidyl choline) are shown to be metabolized by gut microbes to trimethylamine (TMA), which in turn is metabolized by liver flavin monoxygenases (especially FMO3 and FMO1) to form trimethylamine-N-oxide (TMAO). High levels of TMAO in the blood strongly correlate with cardiovascular disease and associated acute clinical eventsDietary modification of the microbiome affects risk for cardiovascular disease.
Checking products for any emulsifiers before buying (and asking your waiter when eating out, which menu items contains no emulsifiers) is strongly recommended — especially if you have any gut or anxiety issues.
Foods commonly containing emulsifiers are:
- “almost every processed food, from ice cream, to low fat cookies and salad dressing contains a wide range of emulsifiers that keep ingredients from separating, improve the texture and taste especially of low-fat foods, and increase shelf life. ” [src]
- salad oils
- some cottage cheese, some cheese (especially processed) and many yogurts [src]
- ice cream
- processed meat
Some of this list from an article entitled “The perfect mixture: emulsifiers make our food enjoyable” . IMHO, it needs a subtitle, “and do a number on your microbiome!’
A list of various names that may be on products [src]:
- Soya Lecithin Granules G
- Soya Lecithin Powder P
- (Ultralec® P & G)
- Soya Lesithin-Powder,Granulate,Liquid
- Distilled Glycerin Monostearate(D…
- Potassium Stearate
- Calcium Stearoyl Lactylate(CSL)
- Glyceryl Monostearate
- Mono Propylene Glycol
- SPAN 80
- Sodium stearoyl lactylate(SSL)
- Sodium Stearate
- Glycerol Triacetate
- Sugar Esters
- Polyglycerol Esters of Fatty Acid…
- Non dairy creamer
- Calcium Stearate
- Polyglycerol Polyricinoleate (PGPR)
- E No: E476
- Soya Lecithin Liquid (Yelkin® TS)
Bottom line: Use the raw ingredients to prepare meals. Beware of all processed foods.