St John's wort, hailed as a natural remedy for depression, could cause cataracts in some patients, says US research.
It is just the latest report of side effects associated with the herb and its active ingredient hypericin.
Joan Roberts, of Fordham University, New York, showed in laboratory experiments that the drug reacts with light, both visible and ultraviolet, to produce free radicals, molecules that can damage the cells of the body.
These, the scientists found, can react with vital proteins in the eye.
Roberts said: "If the proteins are damaged, they precipitate out of solution and make the lens cloudy. That's what a cataract is."Source BBC News