How safe is chitosan for the consumer?
Chitosans are regarded as completely safe for consumers. In fact, chitosan-containing capsules are swallowed by many people as dietary fat blockers and though scientific evidence suggests this is not effective, it also not known to have any negative effects. Consequently, chitosan is also approved as a food and feed additive. Also, chitosan hydrochloride (i.e. chitosan dissolved in water by the addition of small amounts of hydrochloric acid) has been registered as a "basic substance" in the EU, meaning that no harm is expected from its use for humans or the environment. Purified chitosans are also non-allergenic, even in people suffering from a shellfish allergy, and they show no cytotoxicity towards human cells. However, chitosan nanoparticles are easily taken up by human cells, an effect that can be used e.g. for drug delivery, by chitosans with low degree of acetylation are not easily degraded inside the human cells, so that their metabolic fate is unclear. Thus, the development of applications for nano-formulated chitosans needs to be accompanied by careful studies on potential health risks.