  == Protein/Animo Acid section ==  I agree amino acids and nucleic acis would provide very little benefit to hair.  And whole protein molecules would be too large to enter the cuticle. But the section seems to want to argue about *permanently* bonding new amino acids to hair, which of course isn't going to happen in dead cells.  But I haven't seen any conditioner or shampoo marketed as permanently improving hair. Adding hydrolized protein bits that are cationically charged will help temporarily improve the look of damaged or fine fine (until its washed again).  