DHA (docosahexaenoic acid) is recognized as a physiologically essential nutrient in the brain where it is required in high concentrations for facilitating optimal mental performance (neuronal functioning) and in the retina (of the eye), where it is critical for visual acuity. DHA exerts its most crucial functions at the level of the cell membrane, where it is known to significantly affect many of its basic properties including fluidity, permeability, and interactions with key signaling and regulatory molecules. DHA-1000 has twice the DHA (1,000 mg per softgel) than our DHA-500 (500 mg per softgel).