The blood brain barrier is a dense network of capillary walls that are wrapped around the brain to prevent harmful bacteria, viruses, fungi, and other substances from entering the brain, while allowing access to neurotransmitters and nutrients that nourish the brain. Astaxanthin, with a molecular weight of 597 Daltons, readily crosses the blood brain barrier to boost the antioxidant level of the central nervous system, including the eyes and the brain.