All fifteen people with a shrimp allergy took it without reacting
The shellfish allergen is a muscle protein; glucosamine comes from the shell. In a blind challenge, fifteen shrimp-allergic people swallowed 1,500 mg of it, once, with no reaction.
What the study found
Fifteen of fifteen shrimp-allergic people tolerated shrimp glucosamine
The shellfish allergen is a muscle protein; glucosamine comes from the shell. In a blind challenge, all fifteen people with a confirmed shrimp allergy took 1,500 mg of shrimp-derived glucosamine without reacting, and the one US label sourced here carries no shellfish warning at all.
The caveat · Only the tested brands were cleared
Fifteen people and a single dose cannot rule out rare reactions, and the authors limit their conclusion to the manufacturers' products they tested rather than to glucosamine in general. Nothing here tests a poorly purified product or daily use. Chondroitin comes from cattle or shark cartilage.