Branched chain amino acids also known as BCAA is a group of three essential amino acids-leucine, isoleucine & valine. We have discussed basics about BCAA in our earlier blog.
Briefly, BCAA are the building block of proteins. Our body uses 21 amino acids & our body makes a lot of them itself. However 9 of these amino acids also called essential amino acids are not made by our body & we get them from food we eat. Leucine, isoleucine & valine are essential amino acids which we get from our food or supplements.
Structure & metabolism of BCAA differ from other amino acids. As the name suggests BCAA has a chain that branches off to one side. When we talk of metabolism, BCAA ( unlike other amino acids) is broken down into muscle tissue( not liver).
Besides stimulating muscle growth, BCAA helps in regulating how tissues metabolise glucose & controls blood sugar levels.
Let us discuss protein synthesis!
BCAA acts as a building block for larger proteins including those that make up muscle fibres. It also stimulates muscle protein synthesis which helps in muscle gains. Let us take the example of Leucine. It directly stimulates a series of chemical reactions called mTOR signalling pathway which helps in muscle protein synthesis.
Besides, BCAA also inhibits breakdown of protein through a process known as proteolysis. Therefore BCAA has anabolic effect on the body. It promotes the building of molecules, cells & tissue.
BCAA as an energy source
BCAA can also be used as energy source by muscles when supply of glycogen is low. Therefore BCAA is an important energy source for long duration endurance exercise.
Production of neurotransmitters
BCAA are transported into the brain & influence the production of various neurotransmitters such as dopamine, serotonin & noradrenaline. These neurotransmitters are used to transmit messages from one neuron to another
Regulates glucose metabolism
BCAA influences glucose metabolism & controls blood sugar levels. It facilitates entry to glucose into your issue including your liver & skeletal muscle. It may also stimulate secretion of insulin, the transport hormone that transports glucose to different parts of body & tissues. Therefore by uptake of glucose, BCAA helps in reducing blood sugar level. However, it is important to note that high dietary intake of BCAA can impair insulin function & can also lead to elevated glucose levels.
Let us discuss now the impact of excessive intake of BCAA on glucose metabolism.
Research has shown that high intake of BCAA can result in insulin resistance. This happens when tissue does not respond properly to insulin & becomes insensitive to its effects. The result is tissue is unable to take glucose from the bloodstream leading to elevated glucose level in the bloodstream. This insulin resistance is linked to obesity, type 2 diabetes & metabolic syndrome. As discussed above, BCAA stimulates signalling of mTOR signalling pathway. Excess stimulation can impair insulin signalling leading to insulin resistance. In addition to this, BCAA also interferes with metabolism of fatty acids in muscle tissue. This creates intermediate metabolites which impairs insulin function & lead to insulin resistance.
PPM1K enzyme regulates activity of another enzyme BCKD. This enzyme is involved in breakdown of BCAA. If the activity of this enzyme is reduced , less BCAA is broken down leading to high tissue levels of BCAA.
The C allele of PPM1K gene( which encodes PPM1K enzyme) is associated with high levels of insulin resistance & higher blood glucose levels. This is also linked with type 2 diabetes. These effects of insulin resistance & type 2 diabetes arise from high levels of BCAA linked to C allele.
When you have a high fat diet, the impact of BCAA on insulin resistance is more worse. PPM1K gene variants impact weight loss and improvements in insulin sensitivity in response to diets with different fat content.
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