Genetic and epigenetic diseases and disorders are treated with FDA approved dietary compositions in the form of dietary supplements and nutraceuticals. The diseases and disorders to be treated include Rett syndrome, trinucleotide repeat diseases such as Fragile X syndrome, memory impairment, chronic inflammation, pre-cancerous conditions which involve cancer stem cells, and post-cancerous conditions which involve cancer stem cells which have survived in spite of cancer treatment. Treatment options include prophylactic treatment which is initiated prior to the development of the symptoms of the disease or disorder.