Arginine is a conditionally essential amino acid with primary functions in endothelial health and secondary roles in glucose management and cognition.

Arginine is a central component for the production of nitric oxide, a vasodilator which relaxes blood vessels ²⁴. Also via production of nitric oxide, arginine may preserve cognitive abilities during aging and promote the formation of new neurons ^{18, 35}.

Arginine can independently stimulate the release of insulin from the pancreas ²⁴, and it can also protect the pancreas from toxins ³⁹.

Aspartic Acid promotes hormonal health and participates in the urea cycle.

One isomer of aspartic acid supports the release of hormones such as luteinizing hormone, which have a role in fertility and testosterone production ^{8, 30, 37}. In the urea cycle, aspartic acid helps to clear the body of toxins like ammonia ¹⁴.

Glycine is the simplest of amino acids, yet it has some of the most interesting functions.

Glycine’s small structure permits it to form very strong but flexible bonds with other amino acids, proline and hydroxyproline, to form collagen proteins. Collagen proteins are found in our cartilage, tendons, and ligaments ²⁶. Glycine also appears to have a capacity to reduce some symptoms of aging by promoting mitochondrial health ¹⁷.

Isoleucine is one of the three branched chain amino acids, 3 of the most important EAAs.

This amino acid can improve metabolic function and reduce muscle protein breakdown. In the presence of isoleucine, glucose can be more readily absorbed by a muscle ^{4, 10}. Taken pre-exercise, this could help with athletic performance. In a low-energy state, such as with exercise, the body breaks down muscle proteins to obtain amino acids for gluconeogenesis. Isoleucine, by increasing glucose uptake, may limit muscle protein breakdown ¹¹.

Leucine is another branched chain amino acid with principal functions in muscle anabolism and insulin secretion.

Leucine is often viewed as the “main” branched chain amino acid for its ability to stimulate muscle protein synthesis ^{28, 29}. However, proteins cannot be formed in the absence of amino acids additional to leucine, as more than one amino acid is required to form proteins – one of the reasons our Essential Amino Acid Formula is so effective. Similar to isoleucine, leucine can stimulate insulin secretion. However, other regulatory actions are activated at the same time that result in less glucose uptake than with isoleucine alone ¹⁹.

Lysine, although not a significant structural component like glycine, helps in the formation of collagen proteins through enhancement of crosslinks ²¹.

Lysine can also aid in bone health. In a study examining lysine supplementation, those receiving the lysine retained more calcium ⁷.

Methionine is one of only 2 sulfur-containing amino acids.

This is important, as sulfur-containing amino acids participate in regenerating glutathione, one of our bodies most powerful antioxidants ¹³. Oxidation is so detrimental, methionine’s functions extend into improving cardiovascular ³², immume ³⁸, and joint health ²⁷.

Phenylalanine’s chief function is thought to be conversion into another amino acid, tyrosine.

Both are precursors to neurotransmitters, such as phenylethylamine and dopamine ^{16, 20}. Each of these are “feel good” neurotransmitters than can have antidepressant and analgesic effects. Tyrosine also plays a significant role in cognitive health and memory ³.

Taurine is a great amino acid for athletes. Its actions include stabilizing cellular membranes ³¹, enhancing antioxidant status ²⁵, improving insulin sensitivity ²⁵, forming new blood vessels ¹, and increasing blood flow ²³. Supplementation with taurine may improve exercise capacity ⁵ and muscle force output ¹⁵.

Threonine is another amino acid involved in the formation of collagen and connective tissues ¹².

Moreover, threonine is a major amino acid in the production of antibodies, a marker of a healthy immune system. Supplementation with threonine has been observed as necessary for maximal antibody creation ⁹.

Tryptophan is everyone’s favorite Thanksgiving amino acid.

Tryptophan is the amino precursor to the neurotransmitter serotonin and the hormone melatonin ³⁴, which you may also recognize as sleep aids, and turkey has plenty of tryptophan. Serotonin can also improve mood and regulate appetite ²². Melatonin helps regulate the immune ⁶ and gastrointestinal (digestive) systems ³⁶.

Valine is the third and final branched chain amino acid.

Its functions are similar to that of both leucine and isoleucine, albeit to a reduced magnitude. However as one of the branched-chain amino acids, valine can still be utilized as substrate by active muscles ³³.