Hydroxytyrosol and olive polyphenols

What hydroxytyrosol is

Hydroxytyrosol occurs in olives and olive oil, both free and bound, for example as oleuropein, which is abundant in olive leaves. The body absorbs hydroxytyrosol from both forms (Bender 2023). What is offered are olive leaf extracts, extracts from olives and synthetically produced hydroxytyrosol. Related polyphenols with their own page include green tea extract (EGCG) and OPC.

In the BK-Score, human evidence stands at 6 out of 10 points. This axis rates the state of knowledge, not the substance. The official health claim applies to olive oil, not to capsules.

How it works

Hydroxytyrosol is an antioxidant. The EU claim is based on the protection of LDL particles from oxidative damage. In the EUROLIVE study, oxidized LDL fell more, the more polyphenols the olive oil contained (Covas 2006). Oxidized LDL is a surrogate marker, not a clinical endpoint.

Absorption has been measured in humans: after liquid olive extracts with around 31 and 61 mg of hydroxytyrosol, plasma levels peaked after about 30 minutes, and bioavailability rose with the amount; the main breakdown products were homovanillic acid, hydroxytyrosol-3-O-sulfate and 3,4-dihydroxyphenylacetic acid (Bender 2023). Whether less oxidized LDL translates into fewer heart attacks has not been tested in outcome studies.

What the studies show

EUROLIVE: Covas 2006

200 healthy men from 6 centers in 5 European countries took, in random order, 25 ml daily of olive oil with low (2.7 mg/kg), medium (164 mg/kg) or high (366 mg/kg) polyphenol content for 3 weeks each, separated by two-week breaks. HDL rose with all oils, most strongly with the polyphenol-rich one (0.045 mmol/l). Oxidized LDL changed by +1.21, −1.48 and −3.21 U/l; only with the polyphenol-rich oil did the confidence interval exclude zero. As limitations, the authors name the short phases and the self-reported diet.

Hydroxytyrosol as a capsule: Moratilla-Rivera 2025

52 adults aged 40 to 70 with overweight and prediabetes received 15 mg of hydroxytyrosol or placebo for 16 weeks; 49 completed the study. The primary endpoint, oxidized LDL, fell compared with placebo (p = 0.045), as did protein carbonyls, the DNA damage marker 8-OHdG and IL-6. Blood lipids, body measurements, sleep, well-being and physical performance did not change, and no adverse events occurred.

Olive leaf: meta-analyses and a negative study

Mansouri 2026 pooled 30 randomized trials with 1,726 participants on olive leaf and olive pomace. Olive leaf lowered total cholesterol, triglycerides, LDL, ApoB and oxidized LDL, raised ApoA1 and lowered TNF-alpha, systolic and diastolic blood pressure, weight and BMI; blood sugar values remained unchanged, and the certainty of evidence ranged from very low to high. Frumuzachi 2025 found small reductions in total cholesterol, triglycerides and insulin across 14 studies with 594 participants on oleuropein, hydroxytyrosol and tyrosol. By contrast, 500 mg of olive leaf extract daily over 8 weeks in 77 overweight adults with slightly elevated cholesterol changed neither blood lipids nor oxidized LDL, blood pressure or blood sugar (Stevens 2021).

Where the data stop

• Capsules instead of olive oil. The EU claim applies only to olive oil with at least 5 mg of hydroxytyrosol and derivatives per 20 g. There is no approved health claim for capsules.
• Heart attack and stroke. None of the supplement studies analyzed here measured hard endpoints; oxidized LDL is a surrogate marker.
• Inconsistent products. The meta-analyses pool different extracts, amounts and groups, and the certainty of evidence goes down to very low. One placebo-controlled single study found no effect.
• Long-term data. The supplement studies analyzed here lasted 8 to 16 weeks.

Status, approval and legal

The claim on olive oil polyphenols is on the EU list under Regulation 432/2012 and may only be used for olive oil that contains at least 5 mg of hydroxytyrosol and its derivatives, such as oleuropein complex and tyrosol, per 20 g; consumers must be informed that the beneficial effect is obtained with a daily intake of 20 g of olive oil. The underlying EFSA assessment from 2011 also examined claims on HDL cholesterol, blood pressure and anti-inflammatory effects; only the claim on protection from oxidation was included in the EU list.

Synthetically produced hydroxytyrosol is authorized as a novel food after EFSA considered it safe in 2017 at the amounts applied for. The authorization covers fish and vegetable oils other than olive oil up to 0.215 g per kg and spreadable fats up to 0.175 g per kg, with mandatory labeling; it does not cover use in food supplements. Olive leaf extract is sold as a food supplement; there is no approved health claim for it.

Safety

For synthetic hydroxytyrosol, EFSA derived a NOAEL of 50 mg per kg of body weight per day from a subchronic toxicity study and noted that the consumption of olive oil and olives has not been associated with adverse effects. Foods containing synthetic hydroxytyrosol must carry the statement that children under 3 years of age, pregnant women and breastfeeding women should not consume them. In the capsule study with 15 mg daily, no adverse events occurred over 16 weeks (Moratilla-Rivera 2025).

Because olive leaf extract lowered blood pressure in a meta-analysis, taking it alongside blood-pressure-lowering medication should be coordinated with a physician. In the BK-Score, safety stands at 6 out of 10 points; this axis measures how well safety has been studied, not how safe the substance is. This text is for information and does not replace medical advice.

Sources

• Covas MI et al., Ann Intern Med 2006 – EUROLIVE, randomized crossover study, 200 men, olive oil with different polyphenol content
• EFSA 2011 – assessment of health claims on olive polyphenols and protection of LDL particles from oxidative damage (EFSA Journal 2011;9(4):2033)
• Regulation (EU) No 432/2012 – list of permitted health claims made on foods
• Moratilla-Rivera I et al., Clin Nutr 2025 – double-blind study, 49 people with overweight and prediabetes, 15 mg hydroxytyrosol, 16 weeks
• Frumuzachi O et al., Crit Rev Food Sci Nutr 2025 – meta-analysis, 14 studies on oleuropein, hydroxytyrosol and tyrosol
• Mansouri F et al., Nutr Metab Cardiovasc Dis 2026 – meta-analysis, 30 randomized trials on olive leaf and olive pomace
• Stevens Y et al., Eur J Nutr 2021 – placebo-controlled study, 77 adults, olive leaf extract, 8 weeks
• Bender C et al., Nutrients 2023 – crossover study, 12 volunteers, absorption of hydroxytyrosol from food supplements
• EFSA 2017 – safety of synthetic hydroxytyrosol as a novel food (EFSA Journal 2017;15(3):4728)
• Implementing Regulation (EU) 2017/2470 – Union list of novel foods, consolidated version of August 10, 2026