Hydroxytyrosol

Hydroxytyrosol is a naturally occurring polyphenol, a phenylethanoid built on a catechol framework (two adjacent hydroxyl groups on a benzene ring), which gives it its powerful free-radical-scavenging chemistry. It occurs in the olive tree (Olea europaea) and its products, including olives, virgin olive oil, olive leaves and the wastewater from olive milling, and it is also present in wine. In the plant it forms largely from the breakdown of the bitter glycoside oleuropein as olives ripen or when tissue is damaged. Among olive polyphenols, hydroxytyrosol is the major form consumed and is regarded as having the highest antioxidant potency of the group ^[3].

Interest in hydroxytyrosol grew out of studies on the Mediterranean diet, in which olive oil is the principal fat and populations show lower rates of cardiovascular and other chronic diseases ^[1]. Laboratory and animal work attributes to hydroxytyrosol a range of activities beyond simple antioxidation, including anti-inflammatory, anti-platelet and anti-atherogenic effects, and reviews of human intervention studies report that olive polyphenols lower the oxidation of LDL cholesterol and improve several markers of oxidative damage ^[2][3]. Because it is well absorbed after olive oil intake, it is considered one of the more bioavailable dietary polyphenols, though most of it circulates as conjugated metabolites and clinical trials focused specifically on purified hydroxytyrosol remain limited ^[2]. It is marketed as an antioxidant dietary supplement and added to some foods and cosmetic products.

Regulators have examined hydroxytyrosol mainly in the context of olive oil and food use. In the European Union, purified hydroxytyrosol has been authorized as a novel food after a safety assessment ^[4], and the European Food Safety Authority supports a health claim that olive oil polyphenols, including hydroxytyrosol, help protect blood lipids from oxidative stress when olive oil supplies a meaningful amount per serving. In the United States it has been treated as generally recognized as safe for use in certain foods. It is supplied as a concentrated olive extract or as a purer isolated ingredient, in capsules, liquids and powders.

Considered very safe, with olives and olive oil consumed for millennia. Isolated supplement doses are well tolerated in studies, with rare mild GI effects. There's no significant toxicity concern at normal intakes.