Spirulina

Spirulina is the dried biomass of Arthrospira microalgae used in small amounts to add blue‑green color and nutrients. Its safety as a food ingredient has been acknowledged in FDA GRAS notices, but the main concern is contamination with microcystins—liver‑toxic compounds produced by some cyanobacteria in shared waters. EFSA and WHO caution that exposures can exceed the WHO tolerable daily intake (0.04 μg/kg/day) if sourcing and testing are poor, and that accurate, validated testing is essential. On the benefit side, spirulina provides antioxidant pigments such as phycocyanin, and a human study has measured its protein digestibility directly, supporting its role as a usable plant protein. Short‑term human trials commonly use 1–10 g/day and report acceptable tolerability, though gastrointestinal upset can occur at higher doses. Overall, spirulina can be a useful nutrient‑dense color ingredient when sourced and tested carefully; the practical takeaway is to choose brands that publish microcystin testing (preferably LC‑MS/MS) and to start with modest amounts.