Which Amino Acids Cross the Blood-Brain Barrier? A Comprehensive Guide
                                
                                
                                •
                                
                                
                        
                                    
                                    5 min read                                
                            
                                Approximately 98% of small-molecule drugs fail to cross the blood-brain barrier (BBB), but many vital nutrients, including specific amino acids, successfully navigate this biological defense. Understanding which amino acids cross the blood-brain barrier is crucial for appreciating the brain's metabolic needs and its communication with the rest of the body.