Are emulsifiers and sweeteners harmful?
There are serious indications that widely used emulsifiers and artificial sweeteners can disrupt the gut microbiome and may be associated with cancer and other conditions, but solid evidence in humans is still largely lacking. It is prudent to limit ultra-processed products that contain large amounts of these additives.
Emulsifiers such as carboxymethylcellulose (CMC), polysorbate 80 and carrageenan disrupt the gut microbiome in ways that can promote intestinal inflammation. In a small controlled dietary study (16 participants, 11 days), 15 grams of CMC daily led to more gastrointestinal complaints after eating, lower microbiome diversity and fewer beneficial compounds in the stool. In 2 of the 7 participants who received CMC, bacteria penetrated the normally sterile mucus layer of the gut. Lecithin appeared to cause little harm, at least in a laboratory model.
A large French study of 92,000 adults found an association between higher intake of mono- and diglycerides of fatty acids (E471) and a 15% higher risk of cancer overall, a 24% higher risk of breast cancer and a 46% higher risk of prostate cancer. Carrageenan (E407) was associated with a 28% higher risk of breast cancer. These are associations, not proven causal relationships. Other explanations, such as less healthy dietary patterns among people who consume large amounts of these substances, have not been ruled out. Replication in other populations is needed.
Artificial sweeteners have been linked to an increased risk of cardiovascular disease and depression in adults, and to obesity in children. Relatively little targeted research has been done on children as a whole, even though they are the largest consumers of ultra-processed food. Azo dyes and sodium benzoate have also been linked to behavioural problems in children, though the evidence comes from observational studies and animal research.
Both emulsifiers and sweeteners are also associated with worsening irritable bowel syndrome and chronic bowel diseases such as Crohn's disease. The mechanism likely operates through the gut microbiome, but exactly how it works remains largely unclear. Most of the evidence comes from animal research; in humans, the evidence is scarce. If you already have gastrointestinal complaints, discuss your dietary pattern with your doctor or dietitian.
The evidence for the harmful effects of emulsifiers on the gut microbiome rests on laboratory studies, animal research and one small controlled dietary study in humans. The cancer associations come from one large observational study, in which cause and effect have not been demonstrated. The associations with cardiovascular disease, depression and behavioural problems are likewise largely observational or derived from animal research. Overall, there are several concerning signals, but the evidence in humans is limited and causal relationships have not yet been established for most outcomes.
Does coffee activate mTOR?
Coffee does not activate mTOR. Caffeine actually inhibits mTOR, and in humans this mechanism has not yet been directly tested. Whether that inhibition produces any practical benefit in daily life remains unknown.