Alpha-linolenic acid (ALA), an 18-carbon omega-3 essential fatty acid, is the precursor of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA cannot be synthesized by humans and therefore must be entirely acquired from exogenous sources. Evidence for the essentiality of ALA was first provided by a study showing that ALA supplementation reversed the abnormal neurologic signs observed in a 6-year-old girl who suffered from sensory loss and visual complications. Most of the ALA is catabolized via beta-oxidation for energy generation, and a small proportion of it undergoes conversion to produce another two potent members of omega-3 PUFA family: EPA and DHA. Delta 6 desaturase (D6D) enzyme is responsible the conversion of ALA to DHA. Although not conclusive, it was suggested, that the benefits associated with ALA seem to stem mainly from EPA and DHA, and as major consequence of ALA deficiency it appears that EPA and DHA are not adequately produced.

Alpha-ketoglutarate (AKG), an endogenous intermediary metabolite in the Krebs cycle, is a molecule involved in multiple metabolic and cellular pathways. As an intermediate of the tricarboxylic acid cycle, AKG is essential for the oxidation of fatty acids, amino acids, and glucose. Extracellular AKG is a significant source of energy for cells of the gastrointestinal tract. As a precursor for the synthesis of glutamate and glutamine in multiple tissues (including liver, skeletal muscle, heart, brain, and white adipose tissue), AKG bridges carbohydrate and nitrogen metabolism for both conservation of amino acids and ammonia detoxification. Additionally, emerging evidence shows that AKG is a regulator of gene expression and cell signaling pathways (including the mammalian target of rapamycin and AMPactivated protein kinase). Thus, AKG is an attractive dietary supplement in animal and human nutrition to improve cellular energy status, immunity, and health.AKG can decrease protein catabolism and increase protein synthesis to enhance bone tissue formation in the skeletal muscles and can be used in clinical applications. In addition to these health benefits, a recent study has shown that AKG can extend the lifespan of adult Caenorhabditis elegans by inhibiting ATP synthase and TOR. Orally, AKG is used for kidney disease, gastrointestinal disorders, bacterial overgrowth, intestinal toxemia, liver dysfunction, and chronic candidiasis. It is also used for improving peak athletic performance, improving amino acid metabolism in hemodialysis patients, and cataracts. Intravenously, AKG is used for preventing ischemic injury during heart surgery, improving renal blood flow after heart surgery, and preventing muscle protein depletion after surgery or trauma.