Glutamine
Glutamine is the most abundant naturally occurring, nonessential amino acid in the human body, and one of the few amino acids that can directly cross the blood–brain barrier. Humans obtain glutamine through catabolism of proteins in foods they eat. In states where tissue is being built or repaired, like growth of babies, or healing from wounds or severe illness, glutamine becomes conditionally essential.
Omega-6 fatty acid
Linoleic acid (18:2, "n"−6), the shortest-chained omega-6 fatty acid, is one of many essential fatty acids and is categorized as an essential fatty acid because the human body cannot synthesize it. Mammalian cells lack the enzyme omega-3 desaturase and therefore cannot convert omega-6 fatty acids to omega-3 fatty acids. Closely related omega-3 and omega-6 fatty acids act as competing substrates for the same enzymes. This outlines the importance of the proportion of omega-3 to omega-6 fatty acids in a diet.