Threonine, an essential amino acid, which might not be so well known as some of the other amino acids, but it also plays an important part in health, well-being, anabolism, and fat loss. Threonine aids in maintaining/achieving a positive nitrogen balance where muscle growth can occur and is also is used in the formation of proteins itself. Without it, proper muscle protein synthesis cannot occur.
The majority of excess threonine (that’s not immediately used by the body for important processes such as protein synthesis) is used to produce glucose via gluconeogenesis and only a small amount is converted to ammonia and propionyl-CoA, which is then converted to succinyl-CoA, which is an intermediate in the Kreb cycle, making it a very safe amino acid.
Threonine reduces anxiety and serotonin
Threonine reduces the conversion of tryptophan to serotonin and also reduces anxiety, possibly via the lowering of serotonin. (1, 2) Anything that lowers serotonin, will have a positive effect on dopamine, androgens, mood, motivation, well-being, etc…
Threonine deficiency also increases glutamate release, because of a loss of γ-aminobutyric acid (GABA). (15) GABA is anxiolytic, promotes calmness and aids in better sleep.
Threonine boosts glycine levels
Threonine is significantly correlated with glycine, which then positively balance neurotransmitters (3). Threonine is catabolized by threonine dehydrogenase to form L-2-amino-3-oxobutanoate, which is mainly cleaved by 2-amino-3-ketobutyrate CoA ligase, forming glycine and acetyl-CoA (4). Glycine has powerful 5-alpha-reductase activity in the brain and increases allopregnanolone, which is a neurosteroid. Glycine is also neuroprotective and anti-anxiety while increasing mental alertness. More on glycine here…
Threonine improves Muscle efficiency
Threonine increases muscle efficiency by reducing motor impairment and is useful in the treatment of genetic spasticity disorders and multiple sclerosis at a dose of 1 gram daily (5, 6). Threonine will thus benefit sportsmen like target shooting, bow and arrow, etc… by improving fine motor skills.
Threonine is a Lipotropic and helps make the liver lean
Threonine is a lipotropic, which means it aids in transporting fats out of the liver so that it can be used as energy in the body and preventing fatty build-up in the liver. (7) A buildup of fat in the liver can cause non-alcoholic fatty liver disease. There are many different lipotropics (amino acids, fats itself, vitamins and minerals), but are unable to prevent or heal a fatty liver when there are insufficient or an imbalance of amino acids. For instance, an anti-lipotropic effect was seen of methionine (which is actually a potent lipotropic amino acid) when there was a deficiency in threonine. Lipotropics, such as the indispensable threonine, aid in fat loss by increasing fatty acid transport and mobilization.
Threonine is an essential anabolic amino acid
Threonine uptake is indicative of net muscle protein synthesis and is also a rate-limiting amino acid. Meaning, muscle protein synthesis is positively correlated with threonine levels in the body. (8)
Threonine activates muscle protein synthesis via mTOR ⇒ PDK pathway signaling and also increases the cell sensitivity to protein synthesis. (9) The body is able to sense low levels/a deficiency of amino acids and represses muscle protein synthesis.
Threonine uptake is significantly higher for those consuming fat with protein, compared to protein ingestion with low to no fat. (10) Combine fat with your protein meal to get the best amino acid utilization.
Threonines’ importance in building muscle: 10/10
Threonine boosts Immunity
Threonine is an immunostimulant which promotes the growth of the thymus gland. Estrogen causes the thymus to shrink, so threonine might be anti-estrogen.
As described in the above “Glycine” section, when L-2-amino-3-oxobutanoate is not converted to glycine, it is spontaneously converted to aminoacetone, which is further metabolized into methylglyoxal. (13) Methylglyoxal has potent anti-cancer and anti-viral properties. (14)
Foods highest in threonine include cottage cheese, poultry, fish, other meats, lentils, black turtle bean and sesame seeds.
Threonine can also be synthesized from the amino acid aspartate.
Eating enough meat for the day will ensure you have enough threonine, however, you can always supplement more. I recommend the following amino acid blends for your threonine.