What is An Emulsifier and Are They Safe in Our Diets?

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Two recent articles examine emulsifiers and their potential impact on the GI tract and beyond.

Levine et al provide a good overview of the topic of emulsifiers. Key points:

  • Emulsifiers allow “the mixing of water and and water-soluble agents with fats and fat-soluble agents that is they possess both hydrophilic and lipophilic properties”
  • The FDA “has been responsible for approving the use of all direct food additives” (n=~3000) and “for regulatory purposes, [the FDA excluded] some substances that were generally regarded as safe (GRAS) (n=~450)…Precisely how some emulsifiers gained GRAS status is unclear.
  • “Lecithin” is derived from the Greek name for egg yolk (lekithos). “Over the years the use of the term “lecithin” has been taken to include various mixtures of different phospholipids” (not just phosphatidylcholine).
  • Lecithin can provide the substrate “for the production of trimethylamine N-oxide (TMAO)…linked to cardiac events and cardiovascular inflammation.”
  • “The list of emulsifiers that are widely used, but not considered GRAS, most notably include polysorbate 80 (p80), carboxymethylcellulose (CMC) and carrageenan…these emulsifiers have been linked to the disruption of the microbiota and gut mucosal lining…In addition, low-grade inflammation [has been] associated with consumption of emulsifying agents such as CMC and p80” [in mouse models].
  • The International Organization for the Study of Inflammatory Bowel Disease (IOIBD) has recommended that IBD patients “limit consumption of certain commonly encountered synthetic emulsifiers, specifically carboxymethylcellulose (E466/cellulose gum) and polysorbate 80 (E433) [which] are present in many processed foods, such as ice cream. The group also recommends a decrease in foods containing carrageenan”

In the second study by Chassaing et al with 16 healthy adults, the authors studied the effects of CMC in those with an emulsifier-free diet (n=9) or an identical diet enriched with CMC (n=7).

Key findings:

  • Relative to control subjects, CMC consumption modestly increased postprandial abdominal discomfort and perturbed gut microbiota composition in a way that reduced its diversity
  • CMC-fed subjects exhibited changes in the fecal metabolome, particularly reductions in short-chain fatty acids and free amino acids
  • 2 subjects consuming CMC who exhibited increased microbiota encroachment into the normally sterile inner mucus layer, a central feature of gut inflammation, as well as stark alterations in microbiota composition

My take: The dramatic increase in the prevalence of IBD over the past 50 years indicates a strong influence of environment factors, particularly diet. Determining which of these factors are most important will be challenging. These articles indicate that some emulsifiers could be contributing to GI tract inflammation and non-GI tract inflammation as well.

The challenges with identifying dietary factors relate to difficulties with using randomized controlled trials (especially eliminating delicious foods) to assess the impact over a long period of follow-up.

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