Polysorbate 80

Polysorbate 80, also sold as Tween 80 or the food code E433, is a nonionic emulsifier that blends oil and water; in food it smooths ice cream, sauces, and dressings, and in cosmetics it keeps lotions and cleansers uniform. It is made by attaching about twenty units of ethylene oxide to a sorbitan-and-oleic-acid base, a step called ethoxylation, and that step is the first reason for caution. Ethoxylated ingredients can be left contaminated with 1,4-dioxane, a probable human carcinogen, and with residual ethylene oxide. The contamination is a removable trace, and the FDA advises makers to vacuum-strip it out, but a label does not let you confirm that was done, which is why ingredients ending in eth or starting with PEG are worth a second look. The second reason is specific to eating it: a 2015 study in Nature found that polysorbate 80 and a similar emulsifier shifted the gut microbiome and thinned the protective mucus layer in mice, promoting inflammation and metabolic changes. Those are animal and laboratory results, and food-safety agencies still allow it within an intake limit of 25 mg per kg of body weight per day, but the gut work has kept the picture cautious rather than closed, above all for people with inflammatory bowel conditions or diets heavy in processed food. The molecule itself is low in acute toxicity; the open questions are the contamination from how it is made and the emerging gut findings from eating it often.