Tyrosine – The Unsung Hero
By Prithu Nath
Vegetarians are more at risk of a dysregulated Immune system due to the shortage of Tyrosine which basically comes from the intake of proteins.
In a study published this week in the journal Science, the scientists found that phosphorylation of an amino acid called tyrosine – phosphorylation being a process that can turn molecules on or off – is key for activating plant immune receptors. This mechanism is already known to play an essential role in the activation of mammalian receptors, and its mis-regulation is often linked to important chronic diseases and a dysregulated Innate Immune response to Pathogens invading our body.
You must get some amino acids — known as essential amino acids — from food, while others your body makes on its own. Tyrosine is a nonessential amino acid your body makes from the essential amino acid phenylalanine. Low tyrosine levels are rare, but there is some preliminary research that you may need to up your intake during times of stress. Knowing the food sources of this amino acid may help ensure you’re getting what you need.
Other Roles of Tyrosine in the Body
Without tyrosine, your body wouldn’t be able to handle stress or make important hormones. The nonessential amino acid is an essential part of many of the neurotransmitters — brain chemicals — your body needs to combat stress, including epinephrine, norepinephrine and dopamine. Tyrosine is also needed for the proper functioning of your adrenal, thyroid and pituitary glands. These glands are needed to make hormones such as thyroid hormone, which helps regulate the metabolic activities of your organs, and the hormone that maintains fluid and salt balance known as aldosterone. And as a necessary component of melanin, tyrosine also plays a role in determining the pigment of your hair and skin.
Tyrosine helps make several important substances, including (4):
- Dopamine: Dopamine regulates your reward and pleasure centers. This important brain chemical is also important for memory and motor skills (5Trusted Source).
- Adrenaline and noradrenaline: These hormones are responsible for the fight-or-flight response to stressful situations. They prepare the body to “fight” or “flee” from a perceived attack or harm (5Trusted Source).
- Thyroid hormones: Thyroid hormones are produced by the thyroid gland and primarily responsible for regulating metabolism (6Trusted Source).
- Melanin: This pigment gives your skin, hair and eyes their color. Dark-skinned people have more melanin in their skin than light-skinned people (7Trusted Source).
- Because tyrosine can increase the production of neurotransmitters, it’s claimed to act as an antidepressant (25Trusted Source).
Foods High in Tyrosine
Tyrosine is found in a wide variety of foods — from meats to cheese — making it easy to ensure you’re getting what you need. The amount of tyrosine you need each day is linked to the essential amino acid precursor phenylalanine — for adults, that is 14 milligrams per kilogram per day. If you weigh 180 pounds — with weight in pounds divided by 2.2 to determine kilograms of body weight — you need 1.145 milligrams of phenylalanine/tyrosine a day, about half coming from each amino acid.
Some of the best sources of tyrosine include Parmesan cheese with 559 milligrams per ounce, roasted soybeans with 1,392 milligrams per cup and roast beef with 1,178 milligrams per 3-ounce serving. Pork chops, salmon, turkey and chicken are also rich in tyrosine, with 900 to 1,000 milligrams per 3-ounce cooked portion.
Other Food Sources of Tyrosine
Even if you don’t eat foods rich in tyrosine, you’re sure to get what you need eating a varied diet. One egg has 250 milligrams and a cup of cooked white beans 450 milligrams of tyrosine. Eating 1/4 cup of peanuts can help you get 351 milligrams, and 1 ounce of pumpkin seeds yields 306 milligrams. Both diced Swiss and provolone cheese have about 500 milligrams of tyrosine per 1/4-cup serving. Grain sources of the amino acid include oats with 447 milligrams per 1/2 cup and wild rice with 139 milligrams per 1/2 cup.
Role of Protein Tyrosine Phosphatases in Regulating the Immune System
In recent months a lot of focus has been there on the topic of the Dysregulation of our Innate Immune System. Tyrosine mediators of innate immunity are key regulators of an uncontrolled immune response as they interface signals from multiple cellular receptors. Tyrosine phosphorylation plays a role in regulation of the innate immune response through TLRs.
Immune Cells respond to extracellular cues through a variety of receptors on the surface. These signals once transduced across the cell membrane, activate protein tyrosine kinases, which through phosphorylation of substrates on key tyrosine residues, are able to control cellular growth, activation and differentiation pathways. Recent data suggest that protein tyrosine kinases are critical in integrating signals from various cellular receptors, including pathogen detection receptors that mediate the host innate immune response.
Phosphorylation and dephosphorylation of specific aminoacid residues, in particular tyrosine residues, represent a funda-mental mechanism for the activation and inactivation of intracel-lular signaling molecules. Dephosphorylation is performed bya large number of different protein phosphatases. One importantfamily of such proteins is protein tyrosine phosphatases (PTPs).Members of this family play an essential role in the regulation ofcritical cell signaling events, i.e., proliferation, differentiation, andcell survival. Recent studies demonstrated a pivotal role for PTPsin the regulation of inflammatory and antibacterial responses.
T cell activation requires extracellular stimulatory signals that are mainly mediated by T cell receptor (TCR) complexes. The TCR recognizes antigens on major histocompatibility complex molecules with the cooperation of CD4 or CD8 coreceptors. After recognition, TCR-induced signaling cascades that propagate signals via various molecules and second messengers are induced. Consequently, many features of T cell-mediated immune responses are determined by these intracellular signaling cascades. Furthermore, differences in the magnitude of TCR signaling direct T cells toward distinct effector linages. Therefore, stringent regulation of T cell activation is crucial for T cell homeostasis and proper immune responses. Dysregulation of TCR signaling can result in anergy or autoimmunity. In this review, we summarize current knowledge on the pathways that govern how the TCR complex transmits signals into cells and the roles of effector molecules that are involved in these pathways.
A T cell is a type of lymphocyte, which develops in the thymus gland (hence the name) and plays a central role in the immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor on the cell surface. These immune cells originate as precursor cells, derived from bone marrow, and develop into several distinct types of T cells once they have migrated to the thymus gland. T cell differentiation continues even after they have left the thymus.
Groups of specific, differentiated T cells have an important role in controlling and shaping the immune response by providing a variety of immune-related functions. One of these functions is immune-mediated cell death, and it is carried out by T cells in several ways: CD8+ T cells, also known as “killer cells”, are cytotoxic – this means that they are able to directly kill virus-infected cells as well as cancer cells. CD8+ T cells are also able to utilize small signalling proteins, known as cytokines, to recruit other cells when mounting an immune response. A different population of T cells, the CD4+ T cells, function as “helper cells”. Unlike CD8+ killer T cells, these CD4+ helper T cells function by indirectly killing cells identified as foreign: they determine if and how other parts of the immune system respond to a specific, perceived threat. Helper T cells also use cytokine signalling to influence regulatory B cells directly, and other cell populations indirectly. Regulatory T cells are yet another distinct population of these cells that provide the critical mechanism of tolerance, whereby immune cells are able to distinguish invading cells from “self” – thus preventing immune cells from inappropriately mounting a response against oneself (which would by definition be an “autoimmune” response). For this reason these regulatory T cells have also been called “suppressor” T cells. These same self-tolerant cells are co-opted by cancer cells to prevent the recognition of, and an immune response against, tumor cells.
It Might Help Those With Phenylketonuria
Phenylketonuria (PKU) is a rare genetic condition caused by a defect in the gene that helps create the enzyme phenylalanine hydroxylase (19Trusted Source).
Your body uses this enzyme to convert phenylalanine into tyrosine, which is used to create neurotransmitters (4).
However, without this enzyme, your body cannot break down phenylalanine, causing it to build up in the body.
The primary way to treat PKU is to follow a special diet that limits foods containing phenylalanine (20).
However, because tyrosine is made from phenylalanine, people with PKU can become deficient in tyrosine, which can contribute to behavioral problems (21Trusted Source).
Supplementing with tyrosine may be a viable option for alleviating these symptoms, but the evidence is mixed.
In one review, researchers investigated the effects of tyrosine supplementation alongside or in place of a phenylalanine-restricted diet on intelligence, growth, nutritional status, mortality rates and quality of life (22Trusted Source).
The researchers analyzed two studies including 47 people but found no difference between supplementing with tyrosine and a placebo.
A review of three studies including 56 people also found no significant differences between supplementing with tyrosine and a placebo on the outcomes measured (23Trusted Source).
The researchers concluded that no recommendations could be made about whether tyrosine supplements are effective for the treatment of PKU.
Role of Protein Tyrosine Phosphatases in IBD
PTPs play a crucial role for regulating intracellular signaling events. Recent GWAS have associated a number of PTPs with the onset of IBD. Evolving evidence emerges that expression levels of PTPs, mainly PTPN2, PTPN22, and PTPN11are altered in actively inflamed intestinal tissue. Furthermore, thePTPs seem to be critical for protecting intestinal epithelial barrier function, regulating innate and adaptive immune responses, and finally for maintaining intestinal homeostasis. Dysfunction of those PTPs results in aberrant and uncontrolled immune responses that result in chronic inflammatory conditions. This way, it becomes more and more evident that dysfunction of PTPs displays an important factor in the parthenogenesis of chronic intestinal inflammation, in particular IBD. Evidence Regarding Its Effects on Depression Is Mixed
Tyrosine has also been said to help with depression.
Depression is thought to occur when the neurotransmitters in your brain become unbalanced. Antidepressants are commonly prescribed to help realign and balance them (24Trusted Source).
Because tyrosine can increase the production of neurotransmitters, it’s claimed to act as an antidepressant (25Trusted Source).
However, early research doesn’t support this claim.
In one study, 65 people with depression received either 100 mg/kg of tyrosine, 2.5 mg/kg of a common antidepressant or a placebo each day for four weeks. Tyrosine was found to have no antidepressant effects (26Trusted Source).
Depression is a complex and varied disorder. This is likely why a food supplement like tyrosine is ineffective at combating its symptoms.
Nevertheless, depressed individuals with low levels of dopamine, adrenaline or noradrenaline may benefit from supplementing with tyrosine.
In fact, one study among individuals with dopamine-deficient depression noted that tyrosine provided clinically significant benefits (27Trusted Source).
Dopamine-dependent depression is characterized by low energy and a lack of motivation (27Trusted Source).
Until more research is available, the current evidence does not support supplementing with tyrosine to treat symptoms of depression (25Trusted Source).
Immune Activation and Inflammation in Patients with Cardiovascular Disease Are Associated with Higher Phenylalanine to Tyrosine Ratios:
Patients with CAD and higher serum neopterin or CRP levels may exhibit higher Phe/Tyr, an abnormality which is most probably due to impaired PAH activity. Thus Tyrosine should be supplemented via food specially in people with CAD.
Tyrosine, in Combination With Iodine, Produces Thyroid Hormone
“Tyrosine is a nutrient involved in thyroid hormone production and conversion,” Kellman says. One of the best ways to get more tyrosine, an amino acid, is to make sure you’re getting enough protein, Londergan says. Aim for 10 to 35 percent of your calories from protein each day.