Histidine: Structure, Characteristics, Benefits, Deficiency and Natural Sources

Amino acids are vital chemicals for life, incorporated into the body’s proteins.

Histidine is one of the nine essential amino acids. Amino acids are classified as essential and non-essential.

Histidine is classified as a “conditionally essential” amino acid.

The human body cannot synthesize an essential amino acid from other compounds through chemical reactions or at a rate sufficient to satisfy the body’s physiological needs.

Therefore, it must be obtained through food, especially in children.

An amino acid has a straightforward structure composed of a group of amino acids and a side group, or group R.

The main chain of an amino acid is constituted by an amino group or an -NH2 linked to a central carbon molecule followed by a carboxylic acid group, -COOH.


The amine and carboxylic acid groups can donate hydrogen molecules or oxygen and hydrogen molecules to bind to other amino acids.

The side chain, or group R, is located outside the central carbon and is a fingerprint for each amino acid. Each R group is exclusive of the amino acid that is formed.

Histidine is an amino acid obtained by hydrolysis of many proteins.

A rich source is a hemoglobin (the oxygen-carrying pigment of red blood cells) which produces about 8.5 weight percent Histidine.

Histidine was isolated for the first time in 1896 from various proteins.

Babies can not effectively synthesize Histidine, so it is nutritionally essential to be given to children.

Historically, it was considered non-essential for adults, not being included in the diet, but nowadays, it is also considered essential for adults.

In microorganisms, Histidine is synthesized from sugar ribose and adenosine nucleotide triphosphate.

Histidine is classified as an essential amino acid.

However, the side chain of Histidine allows it to act as a base and an acid, donating and accepting protons, which is considered of paramount importance in its role as protein.

Some amino acids are fundamental for folding the protein, assuming a precise conformational form to function.

Protein plays a particular role, like the enzymes that catalyze chemical reactions.

If the amino acids are combined incorrectly, this complex coordination will decompose.

Essential amino acids, such as Histidine, show the importance of personal responsibility and discipline in selecting a diet to receive necessary elements for good health.


In biochemistry, the term amino acid is often referred to as alpha-amino acids: those amino acids in which the amino and carboxylate groups are attached to the same carbon, the so-called α-carbon (alpha carbon).

The general structure of these alpha amino acids is R | H2N-C-COOH | H, where R represents a specific side chain for each amino acid.

The exception to this basic structure is proline, whose side chain is cycled in the main chain, forming a ring structure. A secondary amino group replaces the primary amino group.

Characteristics of Histidine

The chemical structure of Histidine is C6H9N3O2.

A deficiency of this enzyme is present in the metabolic disorder called histidinemia.

The essential amino acids are obtained through daily food, which both animals and humans must consume because they can not be obtained from chemical products.  


Histidine is an essential amino acid that the body needs mainly in the growth stage of children.

Therefore, it is present in the supplement media or the food.

  • It allows the transfer of iron and copper.
  • It controls diarrhea since it increases the absorption of calcium.
  • Prevents internal bleeding and blood coagulation.
  • Regenerates the skin tissues.
  • Recover muscular injuries.
  • Avoid wrinkles
  • Strengthens the cardiovascular system
  • Relieves degenerative ailments and inflammatory diseases.
  • Provides relief to rheumatoid arthritis.
  • It allows for controlling allergic diseases.
  • Regenerates ulcers
  • Treats anemia caused by kidney failure or kidney dialysis.

But excessive consumption would lead to some side effects such as constipation.

Consequences of Histidine deficiency

Histidinemia is an inherited disorder characterized by elevated histidine levels in the blood and urine due to the lack of the enzyme that breaks down Histidine.

Affected people usually have no symptoms and do not need any restriction of diet or therapy.

Where to find Histidine?

Foods containing Histidine are:

  • Lean meat and lamb.
  • Cheese: gruyere, parmesan, roman, swiss, gouda, and goat.
  • Lean pork
  • Turkey and chicken.
  • Food-based on soy.
  • Fish: halibut, tuna, salmon, trout, canned tuna, snapper, mackerel, and sea bass.
  • Seeds and nuts
  • All types of milk and its derivatives: yogurt, sour cream, etc.
  • Eggs
  • Beans and lentils.
  • Whole grains: quinoa, wheat, wild rice, brown rice, bulgur, and couscous.
  • Vegetables and vegetables