Direct evidence was presented that omega-3 supplements reach the brain. However, it did not prevent memory, cognitive function, or hippocampal atrophy. Why did the nutrients that reached the brain fail to protect brain health? A study conducted by researchers at the Keck School of Medicine at the University of Southern California (USC) and published in the international journal eBioMedicine leaves this question open. Kang Seong-hoon, professor of neurology at Korea University Guro Hospital, said, “This study is one of the best-designed studies on DHA (docosahexaenoic acid) supplementation conducted to date.” “The biggest feature is that we directly measured the concentration of DHA in the cerebrospinal fluid and confirmed whether it is actually delivered to the brain.” Kim Ki-woong, a professor of psychiatry at Seoul National University Bundang Hospital, evaluated this study as saying, “We need to look at the successful half and the failed half together.” The successful half is proof of brain delivery. When a supplement containing 2g of DHA was taken daily, the DHA concentration in cerebrospinal fluid increased by about 17% in 6 months. Red blood cell omega-3 index is also average.