Alongside essential fats, our ancestors were also absolutely dependent upon the high protein content (amino acids), the important fat-soluble vitamin E and the minerals and trace elements found in nuts, since meat and fish were hardly in abundance. For example, cashew kernels contain the important amino acid tryptophan (as much as 450 mg in 100 g), a deficiency of which in the brain is responsible for depressive mood disorders. In order for us to produce the growth hormone that we need in the pituitary gland (hypophysis), we need the two amino acids arginine and ornithine, which are present in abundance in peanuts and hazelnuts.