What it is
A sweet extract of luo han guo — the monk fruit prized in Chinese medicine for cough and throat — whose mogrosides run 150–250× sweeter than sugar, used in microscopic amounts.
Why your biology objects
Like stevia, about as benign as a non-caloric sweetener gets: the mogrosides aren't absorbed intact (they're broken down in the colon), so no calories and no glucose or insulin response, with a clean safety review and even some real — if lab-only — antioxidant activity. The catch isn't the fruit: shelf "monk fruit" is almost entirely erythritol by weight, so the bottle's real health question is the bulking polyol, not the mogroside.