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Understanding the Differences Between L-Theanine and L-Tyrosine

In this blog, we will provide insight into L-Theanine and L-Tyrosine, two amino acids with distinct properties and effects on the body. We will discuss their sources, roles in the body, and potential therapeutic applications.

Greta Daniskova

Author - Greta Daniskova

Greta is a BSc Biomedical Science student at the University of Westminster, London.

Greta used MediSearch to find sources for this blog.
MediSearch gives instant answers to medical questions based on 30 million scientific articles.

What is L-Theanine?

L-theanine is a non-protein amino acid found in green and black tea leaves and some mushrooms; one of the umami components of green tea, it contributes to the distinct flavour of tea [1]. Good antioxidant-like activity has been reported in L-theanine, and various other therapeutic effects have been observed, including improvements in brain and gastrointestinal function, improvements in the therapeutic efficacy of certain types of cancer drugs, antihypertensive effects, and improved immune function [2].

L-theanine appears to have a historical reputation as a relaxing agent. Animal neurochemistry studies raise brain levels of several neurotransmitters, including serotonin, dopamine, glutamic acid, and GABA. It also has micromolar affinities for AMPA, Kainate, and NMDA receptors [3]. Neuroprotective properties in rodent models have been linked to its antagonistic effects on group 1 metabotrophic glutamate receptor cells [3].

It is commercially produced as a functional component and used in the food and health products industry for its multiple health benefits [1], sold as tablets or pills that help patients relieve anxiety and tension and induce sleep [4]. L-Theanine Gummies are also available for consumption.

What is L-tyrosine?

L-Tyrosine, sometimes referred to as just tyrosine, is an amino acid essential in producing proteins in the body; it’s also useful for dopamine production in your brain, and it’s involved in producing pigments. People typically find tyrosine in protein-rich foods [5].

Tyrosine is one of the 20 proteinogenic amino acids and a precursor of further secondary metabolites [6]. This amino acid is synthesised de novo in plants and microorganisms. Plants also use it as a precursor of many secondary metabolites, such as electron ‘in-and-out’ carriers, antioxidants, attractants, and defence compounds. Many molecules derived from tyrosine among the plant natural products have ends that have become important in human medicine and nutrition. Examples include morphine and vitamin E [7].

What is the Difference Between L-Tyrosine and L-Thianine?

L-Theanine and L-Tyrosine are both amino acids, but they exhibit diverese properties and effects on the body.

L-Theanine is known for its anxiolytic (anxiety-reducing), stress-easing and sleep-improving properties and its demonstrated cardiovascular, neurological and oncological effects. L-Theanine is considered a therapeutic/medicinal agent and an additive to consumer products. It is synthesised and extracted from plants and derived from green and black tea leaves and some mushrooms [8, 9, 10].

In contrast, L-Tyrosine is an amino acid derived within the body from the amino acid phenylalanine. It is a precursor to a number of crucial molecules, including the neurotransmitters:

  • Dopamine
  • Adrenaline
  • Norepinephrine
  • Thyroid hormones
  • Melanin

In supplement form, L-Tyrosine is often marketed for its supposed ability to enhance alertness, attention and focus.

To sum up, L-Theanine and L-Tyrosine are types of amino acids formulated from completely different sources with contrasting bodily results. L-Theanine, the active ingredient found in tea, is linked to relaxing feelings, whereas L-Tyrosine, a physiologically produced amino acid, is usually used to obtain greater focus and alertness.

What are the Similarities Between L-Tyrosine and L-Thianine?

L-Tyrosine and L-Theanine are both amino acids, but the structures of the two are strikingly different. L-Tyrosine is a proteinogenic amino acid. Amino acids with this distinction are used in the body to build proteins. L-Theanine, by contrast, is a non-protein amino acid, meaning it isn't used in the body to build proteins, although it likely has an essential function in the body [8, 10].

Both L-Tyrosine and L-Theanine found in specific foods. As L-Tyrosine binds most readily to protein, it is found in high-protein foods such as chicken, turkey, fish and dairy products, whereas L-Theanine occurs only in tea leaves.

Regarding their in vivo effects, both L-Tyrosine and L-Theanine have been shown to promote relaxation and improve focus. These ergogenic effects are attributable to each molecule’s unique actions. Specifically, theanine is an amino acid analogue found naturally in savoury green tea leaves and always occurs in conjunction with L-glutamic acid; it is believed to promote relaxation without the sedating effects associated with classical anxiolytic drugs like benzodiazepines, and it supports alert attention/wakefulness without promoting the anxiety often associated with caffeine use. L-Tyrosine is a non-protein amino acid implicated in synthesising neurotransmitters, among its many other functions. It is the precursor to dopamine, norepinephrine, epinephrine, or adrenaline [8, 11].

The chemical structure of L-Tyrosine contains a side chain of a phenol, whereas the chemical structure of L-Theanine contains a side chain of an amide. Although L-Tyrosine is a phenol-type amino acid while L-Theanine is an amide-type amino acid, both L-Tyrosine and L-Theanine are water-soluble [8, 10].

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