TYPES OF AMINO ACIDS

You may have heard of Amino Acids at your local gym, but what are they, how do they work and how many types of amino acids are there? If these are the questions you need answers to keep reading!

Protein is considered to be an essential nutrient, which means that it must be consumed through diet because the human body is unable to make it. The protein that we eat is broken down into the nitrogen-containing amino acids that it is composed of.¹ During digestion, enzymes break the proteins down into peptides (which are short chains of amino acids strung together) and single amino acids. The amino acids are used all over the body to be used to create different types of body proteins like enzymes, hormones, structural proteins (muscle, skin, and other tissues), immunoproteins, transport proteins and more.¹ All of these protein types are important for things like digestion, muscle growth, tissue repair, regulating immune function and SO MUCH MORE!

READ MORE: What Are BCAAs?

TYPES OF AMINO ACIDS

The 20 amino acids that are used to make protein in the body can be classified in several ways, including their structure, electrical charge, polarity, and essentiality. We’re going to focus on essentiality, which looks at the amino acids in terms of the human body’s ability to produce them (or not). Interestingly, every species has different amino acids that are defined as essential. For example, arginine is a non-essential amino acid in humans, but it is essential for dogs because their bodies cannot make arginine.

ESSENTIAL AMINO ACIDS

These cannot be made by the body, and must therefore come from food sources. Some of the best sources of essential amino acids are meat, eggs, poultry, dairy products and dairy protein supplements.

There are 9 essential amino acids, including: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

• Histidine: Works with antioxidant and immune systems. Found abundantly in hemoglobin.²
• *Isoleucine: Helps with wound healing, detoxification processes, immune function and hormone secretion. Needed the formation of hemoglobin and blood sugar regulation. Isoleucine is found in high concentrations in muscle tissue.³
• *Leucine: Important for many metabolic functions. It helps to regulate blood glucose levels, growth/repair of muscle, production of growth hormones and healing of wounds. Leucine is found in high concentrations in muscle tissue.⁴
• Lysine: Involved in collagen formation, antibody production, hormone production and enzyme production. Important for wound and tissue healing.⁵
• Methionine: A sulfur containing amino acid, it is involved in maintenance of skin, hair and nails. Also important for antioxidant and detoxification processes.⁶
• Phenylalanine: Used to produce norepinephrine, which is a neurotransmitter involved in awake/alert cycles, hunger regulation and memory. Used to make other amino acids.⁷
• Threonine: Helps to make collagen, elastin and tooth enamel. Involved in fat metabolism.⁸
• Tryptophan: Serves as a precursor to serotonin and melatonin. Important for immune function. Least abundant of all amino acids, but can be found in dairy, meats, fish, brown rice and soy products.⁹
• *Valine: Involved in growth hormone production, energy metabolism and blood glucose regulation.¹⁰

NON-ESSENTIAL AMINO ACIDS

The human body has the ability to make these amino acids, even if we do not get it from the foods that we eat.

There are 11 non-essential amino acids including: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine.

• Alanine: Involved in energy creation and nervous system function. Also important for immune function.¹¹
• Arginine: Involved in nitric oxide production, so it is involved in blood circulation and wound healing.¹²
• Aspara gine: Involved in muscle protein synthesis and detoxification of the body.¹³
• Aspartic Acid: Involved in energy creation and detoxification.¹⁴
• Cysteine: A sulfur containing amino acid that is involved in detoxification and antioxidant systems. Also found in keratin which is in nails, skin and hair.¹⁵
• Glutamic Acid: Involved in detoxification and creation of neurotransmitters.¹⁶
• Glutamine: Acts as a nitrogen donor in the creation of many other amino acids and compounds in the body. Also involved in detoxification processes.¹⁷
• Glycine: Involved in cell creation and creation of hormones needed for immune function.¹⁸
• Proline: Especially important in joint tissue and skin health and repair. Also important for immune function.¹⁹
• Serine: Important for antibody production as well as fat and fatty acid metabolism.²⁰
• Tyrosine: Serves as a precursor to neurotransmitters dopamine and norepinephrine. Also involved in thyroid hormone production.²¹

CONDITIONALLY ESSENTIAL AMINO ACIDS

These are amino acids that are not usually “essential,” but under conditions of illness or stress, they may become essential.

Conditional Amino Acids include: arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline and serine.

• Ornithine: Ornithine is sort of like the bonus amino acid on this list. If you’ve been counting, this is #21, and there are only 20 protein-forming amino acids. This one is important, though, because it plays a key role in detoxification through the urea cycle. It also helps with immune function.²²

When it comes to amino acids in the diet, the most important thing is getting variety in your diet. If you eat different kinds of meats, plant foods, legumes, protein supplements and amino acid supplements, you are sure to provide your body with all of the building blocks it needs to create important proteins to perform all of the important functions discussed above! Believe it or not, this list is only the tip of the iceberg when it comes to the importance of amino acids in the body. No wonder protein is considered an essential nutrient!

READ MORE: Amp Up Your Results With Intra-Workout BCAAs

^{*Branched Chain Amino Acids (BCAAs) are a special type of essential amino acids. Check out these articles that explain the role and benefits of these special amino acids.}

^{1. Advanced Nutrition and Human Metabolism. (2005). (S. S. Gropper, J. L. Smith, & J. L. Groff Eds. 4th Edition ed.). Belmont, CA: Thomson Wadsworth.}