Hydroxytyrosol is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula . It is a

phenylethanoid Phenylethanoids are a type of phenolic compounds characterized by a phenethyl alcohol structure. Tyrosol and hydroxytyrosol are examples of such compounds. Glycosides The red deadnettle (''Lamium purpureum'') contains phenylethanoid glycosides ...

, i.e. a relative of

phenethyl alcohol Phenethyl alcohol, or 2-phenylethanol, is an organic compound with the chemical formula . It is a colourless liquid with a pleasant floral odor. It occurs widely in nature, being found in a variety of essential oils. It is slightly soluble in wate ...

. Its derivatives are found in a variety of natural sources, notably olive oils and wines. Hydroxytyrosol is a colorless solid, although samples often turn

beige Beige ( ) is variously described as a pale sandy fawn color, a grayish tan, a light-grayish yellowish brown, or a pale to grayish yellow. It takes its name from French, where the word originally meant natural wool that has been neither ble ...

during storage. It is a derivative, formally speaking, of

catechol Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is an organic compound with the molecular formula . It is the ''ortho'' isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It ...

. Hydroxytyrosol and its derivatives occur in olives and in wines.

Occurrence

Olives

left, Oleuropein, bitter compound, an ester of hydroxytyrosol found in green olive">ester.html" ;"title="Oleuropein, bitter compound, an ester">Oleuropein, bitter compound, an ester of hydroxytyrosol found in green olive skin The olives, leaves, and olive pulp contain large amounts of hydroxytyrosol derivative

oleuropein Oleuropein is a glycosylation, glycosylated seco-iridoid, a type of polyphenol, phenolic bitter compound found in green olive skin, flesh, seeds, and leaves. The term oleuropein is derived from the botanical name of the olive tree, ''Olea europaea ...

, more so than olive oil. Unprocessed, green (unripe) olives contain between 4.3 and 116 mg of hydroxytyrosol per 100 g of olives, while unprocessed, black (ripe) olives contain up to 413.3 mg per 100 g. The ripening of an olive substantially increases the amount of hydroxytyrosol. Processed olives, such as the common canned variety containing

iron(II) gluconate Iron(II) gluconate, or ferrous gluconate, is a black compound often used as an iron supplement. It is the iron(II) salt of gluconic acid. It is marketed under brand names such as ''Fergon'', ''Ferralet'' and ''Simron''. Uses Medical Ferrous glu ...

, contain little hydroxytyrosol, as iron salts are catalysts for its oxidation.

Food safety

Hydroxytyrosol is considered safe as a

novel food A novel food is a type of food that does not have a significant history of consumption or is produced by a method that has not previously been used for food. Designer food Designer food is a type of novel food that has not existed on any regional ...

for human consumption, with a

no-observed-adverse-effect level The no-observed-adverse-effect level (NOAEL) denotes the level of exposure of an organism, found by experiment or observation, at which there is no biologically or statistically significant increase in the frequency or severity of any adverse effe ...

of 50 mg/kg body weight per day, as evaluated by the

European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002 ...

(EFSA). In the United States, hydroxytyrosol is considered to be a safe ingredient (

GRAS Gras may refer to: People * Basile Gras (1836–1901), French firearm designer * Enrico Gras (1919–1981), Italian filmmaker * Felix Gras (1844–1901), Provençal poet and novelist * Laurent Gras (disambiguation) * N. S. B. Gras (1884–1956), ...

) in processed foods at levels of 5 mg per serving.

Function and production

In nature, hydroxytyrosol is generated by the

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

that occurs during olive ripening. Oleuropein accumulates in olive leaves and fruit as a defense mechanism against

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

s and

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s. During olive ripening or when the olive tissue is damaged by pathogens, herbivores, or mechanical damage, the enzyme β-glucosidase catalyzes hydroxytyrosol synthesis via hydrolysis from oleuropein.

Metabolism

Shortly after olive oil consumption, 98% of hydroxytyrosol in plasma and urine appears in conjugated forms (65% glucuronoconjugates), suggesting extensive first-past metabolism and a

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 2.43 hours.

Mediterranean diet

Mediterranean diet The Mediterranean diet is a concept first proposed in 1975 by the American biologist Ancel Keys and chemist Margaret Keys. The diet took inspiration from the eating habits and traditional food typical of Crete, much of the rest of Greece, and s ...

s, characterized by regular intake of olive oil, have been shown to positively affect human health, including reduced rates of

cardiovascular diseases Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheuma ...

. Research on consumption of olive oil and its components includes hydroxytyrosol and oleuropein, which may inhibit oxidation of LDL cholesterol a

risk factor In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often use ...

for atherosclerosis, heart attack or stroke. The daily intake of hydroxytyrosol within the Mediterranean diet is estimated to be between 0.15 and 30 mg.

Regulation

Europe

The EFSA has issued a scientific opinion on health claims in relation to dietary consumption of hydroxytyrosol and related polyphenol compounds from olive fruit and oil, and protection of blood lipids from potential oxidative damage. EFSA concluded that a cause-and-effect relationship existed between the consumption of hydroxytyrosol and related compounds from olives and olive oil and protection of blood lipids from oxidative damage, providing a

health claim A health claim on a food label and in food marketing is a claim by a manufacturer of food products that their food will reduce the risk of developing a disease or condition. For example, it is claimed by the manufacturers of oat cereals that oa ...

for consumption of olive oil polyphenols containing at least 5 mg of hydroxytyrosol and its derivatives (

complex and tyrosol) per 20 g of olive oil.

References

{{Estrogen receptor modulators GPER agonists Phenylethanoids Phenol antioxidants Monoamine oxidase inhibitors Phytoestrogens