Extra virgin olive oil: a strong reputation and a mixed trial record

In a review of 3 randomized trials in 2,348 pregnant women, pooling the two that added extra virgin olive oil and pistachios to a Mediterranean diet cut gestational diabetes by 29% against the same diet without them (RR 0.71, 95% CI 0.57 to 0.88). Only two trials fed that estimate, and the oil always came with the nuts. The other strong result is a null one. Pooling 13 trials with 633 people, extra virgin olive oil did not change fasting glucose (SMD -0.07, 95% CI -0.20 to 0.07), and its effects on insulin and HOMA-IR did not reach significance, in trials the authors call too short. The heart reputation rests on weaker ground. Among 7,102 high-risk adults aged 55 to 80 in the PREDIMED trial, those in the top third of extra virgin olive oil intake, about 49 g a day, had a 25% lower risk of cardiovascular events (HR 0.75, 95% CI 0.60 to 0.94). That is an observational finding, because intake was not what the trial randomized. FDA allows only a qualified heart claim for high-oleic oils, about 20 g a day in place of fats higher in saturated fat, and calls its own evidence supportive but not conclusive. The EU register lists the claim that olive oil promotes heart health as non-authorized.

How much is actually in it

• Across 36 USDA samples of extra virgin olive oil, oleic acid averaged 67.8 g per 3.5 oz (100 g) (56.9 to 73.2), saturated fat 15.4 g (13.1 to 18.8) and polyunsaturated fat 9.07 g (5.81 to 15.5). — USDA Foundation Foods record Oil, olive, extra virgin (FDC 748608), 36 samples (n = 36) Evidence E source
  MUFA 18:1 67.8 g, SFA 15.4 g, PUFA 9.07 g per 3.5 oz (100 g), with PUFA varying most (spread 107%)

What a real portion looks like

• The US dietary survey counts one tablespoon of olive oil as 14 g, which carries 126 calories. — FNDDS food Olive oil (fdc 2710186) Evidence E source
  1 tablespoon 14 g = 126 calories, 1 cup 224 g = 2016 calories, 900 calories per 3.5 oz (100 g)

What your body absorbs

• In a double-blind study in 20 volunteers given 5 mg of hydroxytyrosol in different foods, extra virgin olive oil gave the highest plasma level at 30 minutes, 3.79 ng/mL, and urinary hydroxytyrosol of 0.86 mcg/mg creatinine. — 20 volunteers, single 5 mg hydroxytyrosol dose in diverse food matrices (n = 20) Evidence B source
  Plasma 3.79 ng/mL at 30 min with EVOO vs control; urine 0.86 vs 0.63, 0.55 and 0.33 mcg/mg creatinine for fortified refined olive, flax and grapeseed oils
• Eating 17 oz (470 g) of tomatoes cooked with 1.7 tbsp (25 ml) of extra virgin olive oil once a day for 5 days raised plasma trans-lycopene by 82% in 11 people, while tomatoes cooked without oil left it unchanged in 12. — healthy subjects, one tomato meal a day for 5 days, 11 with olive oil and 12 without (n = 23) Evidence B source
  Trans-lycopene +82% (P<0.001) and cis-lycopene +40% with oil vs no significant trans change and +15% cis without oil
• After a 100 g load of extra virgin olive oil, 8 healthy volunteers absorbed its phenols tyrosol and hydroxytyrosol within 60 to 120 minutes, though absorption varied widely between people. — eight healthy volunteers, single oral fat load; separate one-month trial in 14 volunteers (n = 8) Evidence B source
  Phenols peaked at 60 to 120 min in lipoproteins; plasma antioxidant capacity 0.96 to 1.19 mM Trolox at 120 min (p = 0.02); no fasting phenols after one month of 50 g/day

What cooking and storage change

• In 12 obese insulin-resistant women, a meal with vegetables and pasta fried in 0.88 oz (25 g) of extra virgin olive oil gave lower C-peptide responses at 120 to 180 minutes than the same meal with the oil added raw. — 12 obese insulin-resistant women and five lean subjects, two test meals in random order (n = 17) Evidence B source
  C-peptide AUC higher after the raw-oil meal at 120 min (P = .0020), 150 and 180 min (P = .0039); no difference in lean subjects
• In 20 obese people, breakfasts made with oils put through 20 frying cycles raised markers of oxidative stress with sunflower oil but less so with virgin olive oil. — Twenty obese people, four breakfasts in randomized crossover order (n = 20) Evidence B source
  Sunflower oil lowered plasma GSH and GSH/GSSG ratio and raised protein carbonyls compared with virgin olive oil and antioxidant-added oils

What it does to your health

• Observational data from 7102 high-risk PREDIMED participants link the top third of extra virgin olive oil intake, about 49 g a day, with a 25% lower risk of cardiovascular events over 4.7 years. — 7102 high-risk participants from the PREDIMED trial (57.5% women; aged 55-80 years) (n = 7102) Evidence C source
  HR 0.75 (95% CI 0.60 to 0.94) for highest tertile of EVOO; common olive oil HR per 10 g/d 0.93 (0.87 to 1.00)
• A meta-analysis of 4 cohorts and 6 trials linked the highest olive oil intake with 13% lower diabetes risk in cohorts and 22% lower in trials. — 10 studies (4 cohorts and 6 RCT), more than 500,000 subjects (n = 10 studies) Evidence C source
  Cohorts RR 0.87 (0.83 to 0.92), RCTs RR 0.78 (0.70 to 0.88), EVOO subgroup RR 0.75 (0.65 to 0.87)
• In a meta-analysis of 10 studies in 1,073 adults with non-dialysis kidney disease, diets using high-phenolic extra virgin olive oil lowered C-reactive protein by 0.79 mg/L. — Ten studies involving 1,073 participants, adults with CKD stages 1-5 (n = 1073) Evidence C source
  CRP -0.79 mg/L (95% CI -1.37 to -0.21) with high-phenolic EVOO; eGFR +2.44 mL/min/1.73 m2 for MedDiet overall, no harm to potassium or phosphorus

Safety, limits and interactions

• In a double-blind trial in healthy women of reproductive age, 40 g a day of extra virgin olive oil for 8 weeks lowered fasting insulin but raised LDL cholesterol by 5.1 mg/dL compared with sunflower oil. — healthy nulliparous women, 40 g/day for 8 weeks, 12 EVOO and 15 control completers (n = 27) Evidence B source
  Fasting insulin -0.31 U/mL (p = 0.03), LDL +5.1 mg/dL (p = 0.047), no difference in blood pressure

What people believe that the data does not support

• FDA allows only a qualified claim for olive oil and other high-oleic oils, that about 1.5 tablespoons (20 g) a day may reduce heart disease risk when it replaces fats higher in saturated fat. — US food labels for oils with at least 70% oleic acid Evidence E source
  About 20 g a day, supportive but not conclusive evidence, benefit only when replacing saturated fat
• The EU register lists the claim that olive oil promotes heart health as non-authorized, so it may not appear on EU labels. — EU food labels Evidence E source
  Claim status Non-authorized

Who this works differently for

• In 190 women with gestational diabetes, advice to eat three tablespoons of extra virgin olive oil a day cut the need for insulin (RR 0.595) and lowered triglycerides by 43.3 mg/dL by term. — 190 patients with GDM enrolled before week 29 of gestation (n = 190) Evidence B source
  Insulin requirement RR 0.595 (0.361 to 0.967), triglycerides MD -43.3 mg/dL (-66.8 to -19.8), NICU requirement RR 0.367 (0.140 to 0.939)
• In a review of three randomized trials with 2348 pregnant women, pooling the two that supplemented a Mediterranean diet with extra virgin olive oil and pistachios lowered gestational diabetes risk by 29% (RR 0.71). — pregnant women in three trials, 2348 women in total; RR pooled from the two MedDiet plus EVOO and pistachio trials (n = 2348) Evidence A source
  RR 0.71 (95% CI 0.57 to 0.88) for MedDiet plus EVOO and pistachios vs MedDiet alone
• In 38 older adults with probable sarcopenia, 2 tbsp (30 mL) a day of phenolic-rich extra virgin olive oil with a prebiotic for 12 weeks enlarged the rectus femoris by 0.579 cm2 in women compared with refined olive oil. — Thirty-eight participants (69.6 ± 4.1 years; 31 women) with probable sarcopenia (n = 38) Evidence B source
  Rectus femoris cross-sectional area +0.579 cm2 (0.07 to 1.1) in females vs refined olive oil; BIA muscle mass higher at 12-week follow-up

What is still unknown

• A meta-analysis of 13 trials with 633 people found that extra virgin olive oil did not change fasting glucose (SMD -0.07), insulin or HOMA-IR. — 13 related trials comprising a total of 633 subjects (n = 633) Evidence A source
  FBS SMD -0.07 (95% CI -0.20 to 0.07), insulin SMD -0.32 (-0.70 to 0.06), HOMA-IR SMD -0.32 (-0.75 to 0.10)
• A systematic review of 25 human studies found extra virgin olive oil linked to less liver fat in fatty liver disease, but said high-quality randomized trials are lacking. — adults with MASLD in 25 studies, 12 on olive oil alone and 13 on MD emphasizing EVOO (n = 25 studies) Evidence C source
  Improvements in hepatic steatosis and ALT, AST with EVOO, larger at intakes above 30-50 g/day

The bottom line

A 14 g tablespoon carries 126 calories in the US dietary survey, which does not separate extra virgin from refined olive oil. Across 36 USDA samples of extra virgin oil, oleic acid averaged 67.8 g per 3.5 oz (100 g) (range 56.9 to 73.2) and saturated fat 15.4 g. Polyunsaturated fat varied most, from 5.81 to 15.5 g. That record covers fatty acids only and gives no spread for the phenols the oil is sold on. The oil does carry things into the blood. Eating 17 oz (470 g) of tomatoes cooked with 1.7 tbsp (25 ml) of extra virgin olive oil once a day for 5 days raised plasma trans-lycopene by 82% in 11 healthy people, while tomatoes cooked without oil left it unchanged in 12. In 20 volunteers given 5 mg of hydroxytyrosol in different foods, extra virgin olive oil gave the highest plasma level at 30 minutes, 3.79 ng/mL, in a single-dose test with no health outcome. After a 100 g load of the oil, a dose far above normal use, 8 healthy volunteers absorbed its phenols within 60 to 120 minutes, with very high variability between people. Two small meal tests looked at cooking. In 12 obese insulin-resistant women, pasta and zucchini fried in 0.88 oz (25 g) of oil gave lower C-peptide responses at 120 to 180 minutes than the same meal with the oil added raw, and lean subjects showed no difference. In 20 obese people, breakfasts made with oils heated through 20 frying cycles raised oxidative stress markers more with sunflower oil than with virgin olive oil, a different grade from extra virgin, and the abstract gives no sizes. The diabetes picture is contested. A meta-analysis of 4 cohorts and 6 trials linked the highest olive oil intake with 13% lower diabetes risk in cohorts (RR 0.87) and 22% lower in trials (RR 0.78), with an extra virgin subgroup at RR 0.75. Why this differs from the null glucose result is unclear. One analysis measured glucose in short trials, and the other counted diabetes across mixed designs. In 190 women with gestational diabetes, advice to take three tablespoons of extra virgin olive oil a day cut the need for insulin (RR 0.595, 95% CI 0.361 to 0.967) and lowered triglycerides by 43.3 mg/dL. That trial was open, without placebo, and lost 30% and 22% of its two groups. In 10 studies of mixed design in 1,073 adults with chronic kidney disease, diets using high-phenolic extra virgin olive oil lowered C-reactive protein by 0.79 mg/L (95% CI -1.37 to -0.21). A review of 25 studies in fatty liver disease linked the oil to less liver fat, more so above 30 to 50 g a day, and said high-quality randomized trials are lacking. In 38 older adults with probable sarcopenia, phenol-rich oil with a prebiotic for 12 weeks enlarged the rectus femoris in women by 0.579 cm2 (0.07 to 1.1) against refined olive oil, with 11 to 14 people per group. Who should be careful. In a double-blind trial in healthy women who had not given birth, 40 g a day of extra virgin olive oil for 8 weeks lowered fasting insulin by 0.31 U/mL and raised LDL cholesterol by 5.1 mg/dL compared with sunflower oil. Only 27 women finished it. We have no card on allergy or on interactions with medicines for this oil.

Sources

1. exvo-daily-r1-01 · USDA FoodData Central, Foundation Foods
   Oil, olive, extra virgin: MUFA 18:1 c 67.8 g (range 56.9-73.2, median 68.6, 36 samples); Fatty acids, total saturated 15.4 g (range 13.1-18.8, median 15.3, 36 samples); Fatty acids, total polyunsaturated 9.07 g (range 5.81-15.5, median 8.35, 36 samples)
   USDA FoodData Central, Foundation Foods, release 2026-04-30, FDC 748608 · checked 2026-09-30
2. exvo-daily-r1-02 · USDA FNDDS, dataset
   Olive oil (fdc_id 2710186): Energy 900 kcal per 100 g; 1 tablespoon 14 g 126.0 kcal; 1 cup 224 g 2016.0 kcal
   USDA FNDDS, FoodData Central survey release 2024-10-31, FDC 2710186 · checked 2026-09-30
3. exvo-daily-r1-03 · randomized trial
   A double-blind study was performed including 20 volunteers who ingested 5 mg of hydroxytyrosol through diverse food matrices, to discover the influence on pharmacokinetics and bioavailability of HT metabolites (hydroxytyrosol acetate, 3,4-dihydroxyphenylacetic acid (DOPAC), tyrosol, and homovanillic alcohol) of the distinct matrices by UHPLC-ESI-QqQ-MS/MS. ... In this aspect, the intake of extra virgin olive exhibited significantly higher plasma concentrations after 30 min of oral intake (3.79 ng/mL) relative to the control. Regarding the hydroxytyrosol bioavailability, the intake of extra virgin olive oil, as well as fortified refined olive, flax, and grapeseed oils provided significantly higher urinary contents (0.86, 0.63, 0.55, and 0.33 µg/mg creatinine, respectively) compared with basal urine, whereas hydroxytyrosol metabolites showed no significant changes.
   Eur J Nutr, 2021 · checked 2026-09-30
4. exvo-daily-r1-04 · randomized trial
   Plasma lycopene concentrations were measured after 5 days on a low lycopene diet and again after a five-day dietary intervention, in healthy subjects, who consumed one meal per day of tomatoes (470 g) cooked with or without extra virgin olive oil (25 ml olive oil). There was an 82% increase in plasma trans-lycopene (P< 0.001) and a 40% in cis-lycopene (P = 0.002) concentrations in the 11 subjects who consumed tomatoes cooked in olive oil. There was no significant change in trans-lycopene (P = 0.684) and a 15% increase in cis-lycopene (P = 0.007) concentrations in 12 subjects consuming tomatoes cooked without olive oil.
   Asia Pac J Clin Nutr, 2005 · checked 2026-09-30
5. exvo-daily-r1-05 · randomized trial
   In the second study (Postprandial), eight healthy volunteers received an oral fat load consisting of 100 g of extra virgin olive oil. ... Tyrosol and OH-tyrosol were recovered in all lipoprotein fractions, except VLDL, with concentrations peaking between 60' and 120'. However, a very high variability in tyrosol and OH-tyrosol absorption was observed among subjects.
   Nutr Metab Cardiovasc Dis, 2000 · checked 2026-09-30
6. exvo-daily-r1-06 · randomized trial
   After an overnight fast, 12 obese insulin-resistant women (body mass index [BMI], 32.8 ± 2.2 kg/m(2)) and five lean subjects (BMI, 22.2 ± 1.2 kg/m(2)) were randomly assigned to receive two different meals (designated A and B). Meal A was composed of 60 g of pasta made from wheat flour and 150 g of grilled courgettes with 25 g of uncooked oil. Meal B included 15 g of oil in the 150 g of deep-fried courgettes and 10 g of oil in the 60 g of stir-fried pasta. ... In obese women the AUCs for C-peptide were significantly higher after meal A than after meal B at 120 minutes (W [Wilcoxon sign rank test] = 27.5, P = .0020), 150 minutes (W = 26.5, P = .0039), and 180 minutes (W = 26.5, P = .0039).
   J Med Food, 2011 · checked 2026-09-30
7. exvo-daily-r1-07 · randomized trial
   Twenty obese people received four breakfasts following a randomised crossover design consisting of different oils (virgin olive oil (VOO), sunflower oil (SFO), and a mixed seed oil (SFO/canola oil) with added dimethylpolysiloxane (SOX) or natural antioxidants from olives (SOP)), which were subjected to 20 heating cycles. The intake of SFO-breakfast reduced plasma GSH levels and the GSH/GSSG ratio, increased protein carbonyl levels, and induced a higher gene expression of the different NADPH-oxidase subunits, Nrf2-Keap1 activation, gene expression of the antioxidant enzymes in peripheral blood mononuclear cells and antioxidant plasma activities than the intake of the breakfasts prepared with VOO, SOP and SOX.
   Food Chem, 2013 · checked 2026-09-30
8. exvo-daily-r1-09 · cohort analysis
   We assessed 7102 high-risk participants from the PREDIMED trial (57.5% women; aged 55-80 years), all free of CVD at baseline. ... Participants in the highest tertile of cumulative EVOO intake (mean: 49.2 g/d) had a 25% lower risk of the composite outcome (HR: 0.75; 95% CI: 0.60-0.94), with significant reductions in several individual CVD outcomes.
   Am Heart J, 2026 · checked 2026-09-30
9. exvo-daily-r1-10 · meta-analysis
   10 studies (4 cohorts and 6 RCT) involved more than 50,0000 subjects and 2,0000 individuals with diabetes were included in the meta-analysis. A 13% (RR = 0.87, 95%CI = 0.83 - 0.92, P < 0.01) decreased risk of diabetes was shown in Cohort study and 22% (RR = 0.78, 95%CI = 0.70 - 0.88, P < 0.01) decreased risk in RCT study for the highest vs. lowest olive oil consumption. Subgroup analysis results showed that there was a better effect on reducing diabetes risk in age > 50 years(RR = 0.77, 95%CI = 0.70 - 0.89, P < 0.01), Europe(RR = 0.81, 95%CI = 0.72 - 0.86, P < 0.01) and extra virgin olive oil ( RR = 0.75, 95%CI = 0.65-0.87, P < 0.01).
   J Health Popul Nutr, 2025 · checked 2026-09-30
10. exvo-daily-r1-15 · meta-analysis
    Ten studies involving 1,073 participants were included. The MedDiet was associated with a modest improvement in estimated glomerular filtration rate (eGFR) (mean difference 2.44 mL/min/1.73 m2, 95% CI 0.16 to 4.72), though heterogeneity was high (I2 = 90%). ... Notably, a significant reduction in C-reactive protein (CRP) was specifically linked to interventions using high-phenolic EVOO (mean difference -0.79 mg/L, 95% CI -1.37 to -0.21). The diet also improved body composition and reduced blood urea nitrogen, without adversely affecting serum potassium or phosphorus.
    Front Nutr, 2026 · checked 2026-09-30
11. exvo-daily-r1-11 · randomized trial
    Healthy nulliparous women were randomized to 40 g/day of EVOO high in oleic acid and phenols or an identical dose of sunflower seed oil for 8 weeks. ... Twelve women in the EVOO group and 15 in the control group completed the trial. Compliance was >97 % in both groups. EVOO supplementation reduced fasting insulin (-0.31 ± 0.52 U/mL, p = 0.03), but increased LDL cholesterol (+5.1 ± 4.0 mg/dL, p = 0.047).
    Pregnancy Hypertens, 2026 · checked 2026-09-30
12. exvo-daily-r1-16 · FDA qualified health claim
    Supportive but not conclusive scientific evidence suggests that daily consumption of about 1½ tablespoons (20 grams) of oils containing high levels of oleic acid, when replaced for fats and oils higher in saturated fat, may reduce the risk of coronary heart disease.
    FDA, qualified health claim for oleic acid and coronary heart disease, 2018-11-19 · checked 2026-09-30
13. exvo-daily-r1-17 · EU claims register
    POL-HC-7679 Olive Oil Olive Oil promotes your heart health Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7679, snapshot 2026-09-21 · checked 2026-09-30
14. exvo-daily-r1-12 · randomized trial
    This is a multicenter, parallel, randomized controlled trial in which 190 patients with GDM were enrolled before week 29 of gestation and randomized into the Control group and the Intervention group. Patients in the Intervention group received the indication to consume three tablespoons of extra virgin olive oil (EVOO) daily. ... Primary outcomes showed that EVOO consumption was associated with a reduction in insulin requirement (RR 0.595, 95% CI 0.361-0.967, p < 0.05). There was a significant reduction in triglyceridemia in the EVOO-supplemented group compared to controls (MD -43.3 mg/dL, 95% CI -66.8--19.8, p < 0.01).
    Nutrients, 2026 · checked 2026-09-30
15. exvo-daily-r1-13 · meta-analysis of RCTs
    Across the trials, 2348 women were included. Two of the three trials defined the intervention as the Mediterranean diet supplemented with extra virgin olive oil (EVOO) and pistachios, with the control group being Mediterranean diet alone. Meta-analysis of these trials found a significant reduction in the incidence of gestational diabetes in the intervention group compared to the control group (risk ratio=0.71, 95% confidence interval=(0.57, 0.88)).
    Eur J Obstet Gynecol Reprod Biol, 2024 · checked 2026-09-30
16. exvo-daily-r1-14 · randomized trial
    A 12-week randomised, double-blind, parallel, placebo-controlled, three-arm clinical trial was conducted. ... RESULTS: Thirty-eight participants (69.6 ± 4.1 years; 31 women) with probable sarcopenia were assigned to ROO (n = 13), EVOO (n = 14) or EVOO + PREB (n = 11) intervention groups. ... Also, EVOO + PREB compared to ROO increased the cross-sectional area of the rectus femoris (0.579 cm2 [0.07; 1.1], p = 0.026) and rectus femoris muscle thickness (0.133 cm [0.00; 0.27], p = 0.050) in females.
    J Cachexia Sarcopenia Muscle, 2026 · checked 2026-09-30
17. exvo-daily-r1-08 · meta-analysis of RCTs
    We found 13 related trials comprising a total of 633 subjects. In pooled analysis, EVOO intake had no effect on FBS (SMD: -0.07; 95% CI: -0.20, 0.07; I2 = 0.0%), insulin (SMD: -0.32; 95% CI: -0.70, 0.06; I2 = 38.0%), and HOMA-IR (SMD: -0.32; 95% CI: -0.75, 0.10; I2 = 51.0%). ... Furthermore, well-designed RCTs with longer durations are still needed to evaluate the EVOO's efficacy on glycemic parameters.
    Nutr Metab Cardiovasc Dis, 2021 · checked 2026-09-30
18. exvo-daily-r1-18 · systematic review
    This review included 25 high-quality studies, 12 of which assessed olive oil alone and 13 evaluated the MD emphasizing extra virgin olive oil (EVOO). ... Longer study durations and higher EVOO intake (>30-50 g/day) yielded greater improvements. ... However, findings are limited by study heterogeneity and a lack of high-quality randomized controlled trials, highlighting the need for future research to refine optimal dosing, assess long-term outcomes, and clarify underlying mechanisms.
    Nutrients, 2025 · checked 2026-09-30