L-serine is a nonessential amino acid, it occurs naturally in an L-isomer form. L-serine is synthesized from glycine or theonine. It is involved in the biosynthesis of purines, pyrimidines, and other amino acids. L-serine plays a role in cell proliferation. Serine is just one of twenty amino acids which form the building blocks of all the protein that make up the human body. Amino acids are also used in the formation of many enzymes needed for good health. Amino acids form living cells and the antibodies used by our immune systems, carry oxygen throughout the body and are involved in muscle activity. Since all the proteins crucial to our existence are composed of various combinations of amino acids, it is easy to understand their importance.

Serine's known benefits to proper human functioning are numerous. Serine is an integral component of particular phospholipids (fatty compounds) which are important constituents of cellular membranes. Serine also makes up brain proteins and nerve coverings. Serine aids in the production of immunoglobulins and antibodies. Serine, in turn, is needed to produce the amino acid, tryptophan, which is imperative to the construction of other important neurotransmitters. Tryptophan is a natural relaxant, relieves stress, anxiety and depression, and most critically is used in the making of serotonin. This chain of events in our metabolism displays that when we have reduced levels of serine not only do we lose the direct benefit of serine alone, but we will also miss out on the many benefits of tryptophan and serotonin.

What is L-Serine?
Serine is a nonessential amino acid synthesized from glycine, and it also helps derive cysteine from homocysteine. It is one of three amino acids that is usually phosphorylated during cell signaling in eukaryotes. Phosphorylated serine residues are referred to as phosphoserine. Serine proteases are a common type of protease. Serine has sugar-producing qualities, and is very reactive in the body. It is highly concentrated in all cell membranes, helping in the manufacture of immunoglobulins and antibodies.

Serine can be made in the body from either glycine or threonine (making it nonessential), but its production is dependent on sufficient levels of B3, B6, and folic acid. Serine is crucial in metabolism because it participates in the biosynthesis of purines and pyrimidines, cysteine, tryptophan (in bacteria), in the formation of cell membranes, and in creatine synthesis. Serine is also necessary for fat and fatty acid metabolism, muscle growth, and a healthy immune system. It is vital in the production of immunoglobulins and antibodies, and is an integral component of brain proteins and nerve sheaths. It is thus important in the production of cell membranes, as well as in muscle tissue synthesis.

In the United States, L-Serine is sold as a dietary supplement, and dietary supplements are regulated as foods, not drugs. Therefore, premarket evaluation and approval by the Food and Drug Administration are not required unless claims are made for specific disease prevention or treatment.

Where it is found
A select list of dietary sources of serine is provided in the table below.

Benefits / uses
Serine is important to overall physical and mental health, and is especially important to proper functioning of the brain and central nervous system because it helps build the phospholipids required to make every single cell in your body. It is also involved in RNA and DNA function, fat and fatty acid metabolism, muscle formation, and the maintenance of a healthy immune system. The proteins used to form the brain, as well as the protective myelin sheaths that protect the nerves, contain serine. Without serine, the myelin sheaths could become less effective at transmitting messages between the brain and nerve endings in the body, thus short circuiting mental function.

Serine is also required to synthesize tryptophan, an amino acid that is used to manufacture serotonin, a mood-determining brain chemical. Low levels of serotonin and tryptophan have been directly linked to depression, insomnia, confusion, and anxiety. Research indicates that shortages of serine may also contribute or lead to chronic fatigue syndrome (CFS) and fibromyalgia (FM). Serine helps make immunoglobulins and antibodies for a strong immune system, and also aids in creatine absorption, a substance made from amino acids that helps build and maintain all the muscles in the body, including the heart. Serine as a constituent of phospholipids also help seal in moisture, and for this reason it is also often included as a natural moisturizing agent in numerous skin care products.

Doses
Since Serine is a nonessential amino acid, meaning this is an amino acid that can be produced in our body, there is no established RDA. However, 500mg daily has been proven beneficial in numerous clinical studies. You can see the full bulk density/volumetric conversion chart for Serine here.

Possible Side effects / Precautions / Possible Interactions:
Side effects are generally rare but can include nausea, indigestion and insomnia. Although toxicity has not been established it has been found that very elevated serine levels may cause immune suppression and psychological symptoms such as cerebral allergies. Do not take Serine if you are a child, are pregnant or are nursing.

Research studies / References