Euglena gracilis, often regarded as a ‘superfood,’ is a promising microalga with many health and nutritional benefits. In a recent study, researchers found an efficient and low-resource approach to trigger a reddening reaction in E. gracilis using red light and a bonito fish-based culture medium. This reaction is a sign of higher and diverse carotenoid content ratio, meaning the proposed method could help turn E. gracilis into an even more nutritious food source.