Fruits · Fruit
Olives
Olea europaea · also called Olives, table olives, aceitunas (Spanish)
The olive is a small fruit eaten after curing in brine or lye. It is mostly fat, mainly oleic acid, and is high in salt. We found no human trial showing that eating table olives prevents or treats any condition. The main cautions are salt, botulism from badly home-cured olives, rare allergy, and the pit.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Olives
The olive is a fruit eaten mostly cured in salt water. It is a tasty, fatty and salty food, not a proven remedy. The research that sounds promising is mostly about olive oil, the Mediterranean diet or olive compounds in supplements.
What it is
The olive (Olea europaea) is the fruit of the olive tree. Fresh olives are very bitter, so they are cured. Ripe black olives, green olives in brine and naturally fermented olives are the same fruit prepared in different ways.
Figures from our earlier USDA summary: canned ripe olives have about 116 kcal, 10.9 g of fat and 1.6 g of fibre per 100 g. Pickled green olives have about 3.3 g of fibre and 3.81 mg of vitamin E. Sodium is 735 mg per 100 g in canned ripe olives and 1,556 mg in pickled green olives. One tablespoon of canned ripe olives (8.4 g) has about 10 kcal and 62 mg of sodium. These values were not re-checked on USDA today.
What the research shows
A 2020 review of table olives says human studies are scarce. Our searches found no trial or large cohort study that tested eating olives for heart disease, blood pressure, diabetes or cancer.
The small drops in cholesterol, triglycerides and insulin come from supplements of olive compounds. In one set of small studies, olives eaten with bread did not change blood sugar in healthy people. A table olive study in rats lowered blood pressure, which may not apply to people.
Fermented olives carry lactic acid bacteria. The one human trial used a capsule of a strain isolated from olives and measured stool bacteria, not health.
Olives versus olive compounds and olive oil
The cholesterol and insulin findings come from hydroxytyrosol and oleuropein supplements. The blood sugar benefit was seen with a leaf extract. The gut trial used a bacteria capsule. Olive oil is a different food. Results for one form do not carry over to another.
Amounts
This page gives no amounts to eat. Ask a doctor or pharmacist what is right for you, especially if you limit salt or take medicine.
At a glance
Traditional uses history, not proof
- Eaten as a salty snack, in salads and in cooking across the Mediterranean
- Part of the Mediterranean diet; long use is not proof of a health effect
Studied for research
- Blood fats and insulin, low certainty (olive compounds as supplements, not olives)
- Blood pressure, insufficient (rat study only)
- Blood sugar after bread, low certainty and no effect from olives
- Gut health, insufficient (a bacteria capsule, not olives)
- Disease prevention from table olives, insufficient
Main compounds
- Monounsaturated fat (oleic acid)
- Hydroxytyrosol and oleuropein
- Vitamin E
- Fibre
- Sodium from brining
Common forms
- Ripe (black) canned olives
- Green olives pickled in brine
- Fermented or naturally brined olives
- Stuffed or marinated olives
- Oleuropein and hydroxytyrosol supplements (used in trials; not the same as olives)
Research links: Table olives and health: a review (2020) · Meta-analysis of olive compounds and heart risk factors (2025) · Botulism and preserved green olives (CDC EID, 2005) · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Olea europaea
- Naming authority
- L. (as given in the Rocha 2020 review as Olea europaea L.)
- Common names
- Olives (English); Table olives (English); Aceitunas (Spanish)
- Family or group
- Not verified from a source read.
- Classification
- Plantae > Olea > Olea europaea
- Native range
- Not verified from a source read.
- Habitat
- Not verified from a source read.
- What it looks like
- Roots: Not verified.; Stems: Not verified.; Leaves: Not verified.; Flowers: Not verified.; Fruit: The fruit is the food. It has a pit (stone) inside; the pit is a swallowing hazard (case report).
- Cultivation
- Not verified from a source read.
- Harvest and processing
- Fresh olives are very bitter and are cured before eating. Reviews describe Spanish-style green olives, directly brined (naturally fermented) olives and California-style black ripe olives, which are lye-treated. The cultivar, ripening stage and processing method change the composition (Rocha 2020).
- Look-alikes and adulterants
- Name: Olive oil; Note: A separate food pressed from olives. Most heart-health research is on the oil or the Mediterranean diet, not table olives.; Name: Olive leaf and olive leaf extract; Note: A different plant part with its own trials and cautions.
- Sustainability and conservation
- Not assessed.
Photographs
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Mediterranean diet | The 2020 review calls table olives an important fermented product of the Mediterranean Diet. It does not give a history of use. | p33354328 |
| Canned olives and botulism | A 2011 history paper on the 'ripe olive scare' and a 2018 paper on canned food botulism in the 1920s exist, but only titles were seen, so no history is stated here. | Not verified |
Traditional use shows how it was used. It does not show that it works or is safe today.
What is inside, and how it may work
What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.
Main compounds
| Compound | Family | Where it is concentrated | Activity studied | Level of evidence |
|---|---|---|---|---|
| Oleic acid and other monounsaturated fat | fatty acid | Flesh USDA: 10.9 g total fat per 100 g of canned ripe olives | The review names monounsaturated fat, mainly oleic acid, as the main fat in table olives. No olive-specific trial of it was read. 14 20 | Composition only |
| Hydroxytyrosol | phenolic compound | Flesh | The main phenolic compound in all types of table olives (review). Supplement trials show small changes in some blood markers. 14 4 3 | Human data |
| Oleuropein | secoiridoid | Olives and olive leaves | Blocked sugar-digesting enzymes in the lab. Olives did not change blood sugar after bread in healthy volunteers. 10 | Human data |
| Vitamin E | vitamin | Flesh USDA: 3.81 mg per 100 g of pickled green olives | An antioxidant vitamin. The review says olives are a source. 14 20 | Composition only |
| Lutein plus zeaxanthin | carotenoid | Flesh USDA summary: 510 micrograms per 100 g | Present; no olive trial of these was found. 20 | Composition only |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Sugar digestion enzymes and glucose transport | Maltase, sucrase, GLUT2 | In the lab, an oleuropein extract blocked maltase, sucrase and glucose uptake, but was a weak blocker of alpha-amylase. 10 | Laboratory research |
| Gut bacteria | Not specified | Arbequina olives changed gut bacteria in hypertensive rats; a strain from olives changed stool bacteria in healthy people as a capsule. 6 11 | Animal research |
| Sodium and blood pressure | Not applicable | Brined olives add sodium, and cutting sodium lowers blood pressure, most in people with kidney disease or hypertension. 8 19 | Human data |
Absorption, metabolism and elimination
- Absorption
- Not studied for table olives. A 2023 randomised trial looked at hydroxytyrosol from food supplements; it was not read.
- Distribution
- Not found.
- Metabolism
- Not found.
- Elimination
- Not found.
- Bioavailability
- Not established for olives.
Isolated compounds versus whole extracts
The blood fat and insulin results are for oleuropein, hydroxytyrosol and tyrosol supplements. The blood sugar result with a clear effect is for an olive leaf extract. The gut trial used a bacteria capsule. The only olive-fruit findings are no effect on blood sugar after bread, and an animal blood pressure result. Results for one form do not carry over to another.
Nutritional composition
Nutrition values come from our earlier summary of USDA FoodData Central, which records them as read: ripe olives, canned (FDC 169094) and olives, pickled, canned or bottled, green (FDC 169096). A fresh check on 2026-10-26 could not be done because the USDA API demo key was over its rate limit, so these are marked summary-only. Canned ripe olives per 100 g: about 116 kcal, 10.9 g fat, 1.6 g fibre, 735 mg sodium (32 percent of the Daily Value), 6.28 mg iron (35 percent) and 0.25 mg copper (28 percent). Pickled green olives per 100 g: about 3.3 g fibre, 1,556 mg sodium (68 percent of the Daily Value) and 3.81 mg vitamin E (25 percent). One tablespoon of canned ripe olives (8.4 g, USDA household portion): about 10 kcal, 0.9 g fat and 62 mg sodium (scaled from the per-100-g values). The summary notes that the higher iron in ripe olives has no verified reason. Values vary with variety, brine and curing. Olives are mostly a source of fat and salt, with small amounts of other nutrients per portion.
2 low certainty3 not enough evidence
What was looked at
The 5 benefits and uses checked for Olives, each with how strong the evidence is. Tap one to open it.
- Blood fats and insulin (olive compounds as supplements, not table olives)Low certainty
- Blood pressure (table olives)Not enough evidence
- Blood sugar after a starchy meal (olives eaten with bread)Low certainty
- Gut health and fermented olivesNot enough evidence
- Disease prevention and everyday nutrition from table olivesNot enough evidence
Lab markers tracked in the studies
Total cholesterolTriglyceridesInsulin (blood level)Blood glucose after a meal
What is Olives good for?
The main studied uses and how strong the human evidence is for each. Most results are for olive compounds as supplements, or for animals, not for eating olives.
Benefits, one by one
Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.
Blood fats and insulin (olive compounds as supplements, not table olives)
Low certaintyOlives contain hydroxytyrosol and oleuropein. Trials of these compounds as capsules or enriched products found small drops in total cholesterol, triglycerides and insulin. Nobody has tested table olives themselves, so this does not show that eating olives does the same.
3 studiesSupplements, pure compounds and enriched foods. Not the same as table…
Studies, doses and limits
What the trials found
A 2025 meta-analysis of 14 human studies (594 people) of oleuropein, hydroxytyrosol and tyrosol supplements found small drops in total cholesterol (SMD -0.19, 95% CI -0.37 to -0.01), triglycerides (SMD -0.32, -0.60 to -0.03) and insulin (SMD -0.42, -0.82 to -0.01). Heterogeneity was moderate to high for triglycerides and insulin (I2 73% and 78%). A 2024 systematic review of 12 randomised trials (683 people) of supplements, pure compounds or enriched foods called the results contrasting but encouraging and said optimal doses are unknown.
Results
Small changes in some blood markers with concentrated compounds. No trial of eating table olives was found.
Effect sizes as reported
Total cholesterol SMD -0.19; triglycerides SMD -0.32; insulin SMD -0.42 (supplements).
Why this rating
Low for the compounds, because the confidence intervals nearly touch zero and results vary widely between studies. Very low for table olives, which were not tested.
Form and dose studied
Supplements, pure compounds and enriched foods. Not the same as table olives.
Who was studied
Adults in mixed trials; benefit may be larger in people with cardiometabolic disease (meta-analysis subgroup).
Limits
Supplement trials only. Different compounds, amounts and lengths. The review authors say more studies are needed.
Why researchers looked
Olive oil and the Mediterranean diet are linked with heart health, and researchers asked whether the phenolic compounds in olives are part of the reason.
Traditional use
Olives have long been a Mediterranean food. Long use is not proof that they treat any condition.
Proposed mechanism Preliminary mechanism
Hydroxytyrosol is the main phenolic compound in all types of table olives (review). The authors of the supplement reviews suggest these compounds may affect blood fats and glucose handling, but this is a hypothesis.
A proposed mechanism does not show that the effect happens in people.
Table olives are salty. See the Safety tab.
Blood pressure (table olives)
Not enough evidenceOne study found that feeding Arbequina table olives to rats bred to have high blood pressure lowered their blood pressure. We found no trial in people. Because olives are salty, the main official advice about them and blood pressure is about salt.
3 studiesArbequina table olive material given by gavage to rats.
Studies, doses and limits
What the trials found
A 2020 review of table olives and health says there is a scarcity of in vitro, in vivo and human studies of table olives. No human blood pressure trial of table olives was found in our PubMed searches.
Results
Animal result only. In spontaneously hypertensive rats, Arbequina olives given for 7 weeks lowered blood pressure by about 19 mmHg.
Effect sizes as reported
Rats: about -19 mmHg (3.85 g per kg by gavage). No human data.
Why this rating
Animal evidence only. No human trial found.
Form and dose studied
Arbequina table olive material given by gavage to rats.
Who was studied
Rats only.
Limits
Animal study. Rat doses and route are not like eating olives.
Why researchers looked
Olives are part of the Mediterranean diet, which is linked with lower heart risk.
Traditional use
Olives have long been a Mediterranean food. Long use is not proof that they treat any condition.
Proposed mechanism Preliminary mechanism
In the rat study, olive feeding changed gut bacteria and lowered markers of oxidative stress and angiotensin II. This is animal work and may not apply to people.
A proposed mechanism does not show that the effect happens in people.
Olives are high in sodium, and cutting sodium lowers blood pressure most in people with high blood pressure or kidney disease (2026 meta-analysis).
Blood sugar after a starchy meal (olives eaten with bread)
Low certaintyA set of small crossover studies in healthy volunteers found that the oleuropein naturally present in olives did not change blood sugar after bread. A water-soluble olive leaf oleuropein extract did lower blood sugar after a small amount of sucrose, but not after larger sugar loads.
1 studiesOleuropein from olive leaves in capsules or solution; olives as food …
Studies, doses and limits
What the trials found
A 2019 paper reported 7 crossover, controlled, randomised studies in healthy volunteers. Oleuropein in capsules, in solution or as naturally present in olives did not affect blood glucose after bread. The olive leaf oleuropein solution lowered blood glucose after 25 g of sucrose, but had no effect with 50 g of sucrose or glucose.
Results
No effect of olives on blood sugar after bread. A small effect of an extract with a small sugar dose.
Effect sizes as reported
Not given in the abstract.
Why this rating
Small studies in healthy people at single meals. The positive result was for a leaf extract, not olives. Two authors have industry ties (see the study record).
Form and dose studied
Oleuropein from olive leaves in capsules or solution; olives as food in one arm. Trial detail, not advice.
Who was studied
Healthy volunteers.
Limits
No people with diabetes; number of volunteers is not given in the abstract; short term.
Why researchers looked
Oleuropein from olives was seen in the lab to block sugar-digesting enzymes, so researchers tested whether olives lower blood sugar after meals.
Traditional use
Olives have long been a Mediterranean food. Long use is not proof that they treat any condition.
Proposed mechanism Preliminary mechanism
In the lab, the oleuropein extract blocked the enzymes maltase and sucrase and sugar transport, but was only a weak blocker of alpha-amylase, which digests starch. The authors say a threshold strength is needed to change blood sugar in people.
A proposed mechanism does not show that the effect happens in people.
People with diabetes should ask their care team before changing meals.
Gut health and fermented olives
Not enough evidenceFermented table olives carry lactic acid bacteria, and some strains from olives are being studied as probiotics. The one human trial we found gave a strain from olives as a capsule, not olives themselves. No trial has tested eating olives for gut health.
2 studiesCapsule with 10 billion colony-forming units a day of one strain (tri…
Studies, doses and limits
What the trials found
A 2023 single-blind placebo-controlled trial in 39 healthy volunteers gave a capsule of Lactiplantibacillus pentosus LPG1, isolated from table olive fermentation, for 30 days (n=20 versus 19 on placebo). Stool sequencing showed a changed gut bacteria pattern, with more Parabacteroides and Agathobacter and less Prevotella. The placebo group lost diversity. A 2024 mini-review calls fermented olives and olive pomace of potential benefit, with a focus on lactic acid bacteria.
Results
Changes in stool bacteria with a capsule of one strain. No health outcome measured and no trial of olives themselves.
Effect sizes as reported
Not given in the abstract.
Why this rating
A small trial of a capsule, with microbiome markers only, plus a mini-review. Not evidence about eating olives.
Form and dose studied
Capsule with 10 billion colony-forming units a day of one strain (trial detail, not advice). Many table olives are pasteurised or brined in ways that may not keep live bacteria; this was not checked.
Who was studied
Healthy adults.
Limits
Single-blind, 39 people, bacteria in stool rather than symptoms.
Why researchers looked
Fermented foods are popular for gut health and olives are a plant-based fermented food.
Traditional use
Olives have long been a Mediterranean food. Long use is not proof that they treat any condition.
Proposed mechanism Preliminary mechanism
Lactic acid bacteria in fermentation may act as probiotics, and olive fibre and phenolics may feed gut bacteria. The 2024 mini-review describes this as potential, not shown.
A proposed mechanism does not show that the effect happens in people.
None specific.
Disease prevention and everyday nutrition from table olives
Not enough evidenceTable olives supply mostly fat, mainly oleic acid, with fibre and vitamin E. A 2020 review says possible benefits are expected from these, but human studies of table olives are scarce. We found no trial or cohort study showing olives prevent any disease.
1 studiesTable olives as food.
Studies, doses and limits
What the trials found
The 2020 review says there is a scarcity of in vitro, in vivo and human studies of table olives. Our PubMed searches for cohorts, case-control studies and trials of table olive intake and disease found none that tested olives themselves.
Results
No disease outcome has been shown for eating table olives.
Why this rating
No human outcome studies of table olives were found.
Form and dose studied
Table olives as food.
Limits
Evidence on olive oil and the Mediterranean diet does not prove the same for olives.
Why researchers looked
Olives are part of the Mediterranean diet, so people ask whether they share its benefits.
Traditional use
Olives have long been a Mediterranean food. Long use is not proof that they treat any condition.
Proposed mechanism Authoritative guidance
The review points to monounsaturated fat, the antioxidant role of vitamin E, and hydroxytyrosol. These are expectations from composition, not tested outcomes.
A proposed mechanism does not show that the effect happens in people.
See sodium on the Safety tab.
Connections to the rest of health
How Olives connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.
Explore every connection: goals, body systems, organs, symptoms, genes
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Cardiovascular System | Biological association | Low certainty | Studied for: Blood fats and insulin (olive compounds as supplements, not table olives) Studied for: Blood pressure (table olives) | 4 3 14 6 8 |
| Heart Circulation | Biological association | Low certainty | Studied for: Blood fats and insulin (olive compounds as supplements, not table olives) Studied for: Blood pressure (table olives) | 4 3 14 6 8 |
| Metabolism Weight | Biological association | Low certainty | Studied for: Blood sugar after a starchy meal (olives eaten with bread) Studied for: Disease prevention and everyday nutrition from table olives | 10 14 |
| Blood Sugar Support | Biological association | Low certainty | Studied for: Blood sugar after a starchy meal (olives eaten with bread) | 10 |
| Digestive System | Biological association | Not enough evidence | Studied for: Gut health and fermented olives | 11 12 |
| Gut Health | Biological association | Not enough evidence | Studied for: Gut health and fermented olives | 11 12 |
E. Health conditions
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Essential hypertension | Documented risk | Olives are a salty food; sodium reduction lowers blood pressure most in people with hypertension or kidney disease. Brined olives are a salty food. Preparation or compound: Brined table olives (sodium) |
8 19 | |
| Foodborne botulism | Adverse effect or risk | Documented risk | Outbreaks in Italy (2004) and Finland (2011) were linked to preserved olives. Preparation or compound: Improperly home-cured olives |
15 9 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Total cholesterol | Biological association | Low certainty | Measured in trials: decrease. A lab change is not the same as a health benefit. | 4 |
| Triglycerides | Biological association | Low certainty | Measured in trials: decrease. A lab change is not the same as a health benefit. | 4 |
| Insulin (blood level) | Biological association | Low certainty | Measured in trials: decrease. A lab change is not the same as a health benefit. | 4 |
| Blood glucose after a meal | Biological association | Low certainty | Measured in trials: no-change. A lab change is not the same as a health benefit. | 10 |
K. Biological pathways
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Oleic acid and other monounsaturated fat | Biological association | Composition only | The review names monounsaturated fat, mainly oleic acid, as the main fat in table olives. No olive-specific trial of it was read. Preparation or compound: Flesh |
14 20 |
| Hydroxytyrosol | Biological association | Human | The main phenolic compound in all types of table olives (review). Supplement trials show small changes in some blood markers. Preparation or compound: Flesh |
14 4 3 |
| Oleuropein | Biological association | Human | Blocked sugar-digesting enzymes in the lab. Olives did not change blood sugar after bread in healthy volunteers. Preparation or compound: Olives and olive leaves |
10 |
| Vitamin E | Biological association | Composition only | An antioxidant vitamin. The review says olives are a source. Preparation or compound: Flesh |
14 20 |
| Lutein plus zeaxanthin | Biological association | Composition only | Present; no olive trial of these was found. Preparation or compound: Flesh |
20 |
Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).
Evidence at a glance: what changed in 1 lab markers
Tap a number to show only those markers. Counts are markers, not people.
The evidence
The research centre for Olives. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).
How we rate evidence
High certainty
Several well-run trials or reviews agree; further research is unlikely to change the picture much.
Moderate certainty
Good trials point the same way, but some doubt remains.
Low certainty
Small, short or inconsistent trials. The finding could change with better research.
Very low certainty
Very little or very weak human data. Treat as a possibility only.
Mixed findings
Trials or reviews disagree with each other.
Not enough evidence
Not enough human research to say either way.
Evidence against
Good research found no benefit, or found harm.
We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing olive summary, searched PubMed for human trials, reviews, case reports and food analyses, and read NHS, FDA and CDC pages. Only abstracts were read for most studies. Nutrition figures come from our earlier USDA summary and were not re-checked today.
Study library: every study we checked 20
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Bolanaki 2024 Intestinal Obstruction Due to Ingested Olive Pits. Cureus · PMID 39650994 · DOI |
Case report |
1 70-year-old woman |
Swallowed olive pits Pit |
Pits tightly impacted in the distal ileum; removed at surgery after conservative treatment failed. Single case Methods, limits and fundingOutcomes: Bowel obstruction Limitations: One case. Funding and conflicts: No conflicts declared. Read: abstract |
| Feo Brito 2011 Anaphylaxis due to olive fruit after pollen immunotherapy. J Investig Allergol Clin Immunol · PMID 21462812 |
Case report |
1 Not stated (no abstract) |
Olive fruit Fruit |
Title only: anaphylaxis due to olive fruit after pollen immunotherapy. No abstract was available, so no details are given. Methods, limits and fundingOutcomes: Anaphylaxis Limitations: Title-level record only. Funding and conflicts: Not stated. Read: title-only |
| Frumuzachi 2024 Systemic Health Effects of Oleuropein and Hydroxytyrosol Supplementation: A Systematic Review of Randomized Controlled Trials. Antioxidants (Basel) · PMID 39334699 · DOI |
Systematic review |
683 12 human randomised trials |
Supplements, pure compounds or enriched foods with oleuropein and hydroxytyrosol From 5 mg a day of hydroxytyrosol to 990 mL a day of olive leaf infusion (trial detail, not advice) Varied · vs Various |
Contrasting but encouraging results: some studies reported changes in body weight, blood fats and glucose, and in bone, joint and cognitive function. Methods, limits and fundingOutcomes: Cardiovascular risk factors, liver, bone, joint and cognitive health Limitations: Different doses and forms; the authors say optimal dosing and duration are unknown. Funding and conflicts: The record says the authors declare no conflicts of interest. Read: abstract |
| Frumuzachi 2025 The impact of oleuropein, hydroxytyrosol, and tyrosol on cardiometabolic risk factors: a meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr · PMID 39828996 · DOI |
Meta-analysis |
594 14 human intervention studies |
Oleuropein, hydroxytyrosol or tyrosol supplements (not table olives) Varied; trial detail, not advice Varied · vs Control |
Small falls in total cholesterol, triglycerides and insulin. Subgroups suggested larger benefit in people with BMI under 30, outside Mediterranean countries, and with cardiometabolic disease. Total cholesterol SMD -0.19; triglycerides SMD -0.32; insulin SMD -0.42 (-0.37 to -0.01; -0.60 to -0.03; -0.82 to -0.01) Methods, limits and fundingOutcomes: Cardiometabolic risk factors Limitations: Supplements, not olives; high heterogeneity for triglycerides (I2 73%) and insulin (I2 78%); the authors say more studies are needed. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Garcia-Garcia 2000 Content of biogenic amines in table olives. J Food Prot · PMID 10643779 · DOI |
Other n/a |
Flesh and brines of table olives (lab analysis) | Table olives, Spanish-style and directly brined Fruit Up to 12 months of brining · vs Fresh fruit |
None in fresh flesh; putrescine highest; cadaverine after 3 months; histamine, tyramine and tryptamine after 12 months; zapatera spoiled olives much higher. Methods, limits and fundingOutcomes: Biogenic amines Limitations: Food analysis only; amounts not given in the abstract; no health outcome. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Gomez-Contreras 2023 Dietary intake of table olives exerts antihypertensive effects in association with changes in gut microbiota in spontaneously hypertensive rats. Food Funct · PMID 36861461 · DOI |
Animal research rat |
Spontaneously hypertensive rats and normal Wistar-Kyoto rats | Arbequina table olive Fruit 3.85 g per kg by gavage (animal detail, not advice) 7 weeks · vs Water |
Blood pressure fell by about 19 mmHg, with lower malondialdehyde and angiotensin II and a changed gut bacteria pattern. About -19 mmHg in rats Methods, limits and fundingOutcomes: Blood pressure, oxidative stress markers, gut bacteria Limitations: Animal study only. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Holzle 2023 Heat-Introduced Formation of Acrylamide in Table Olives: Analysis of Acrylamide, Free Asparagine, and 3-Aminopropionamide. J Agric Food Chem · PMID 37647584 · DOI |
Other n/a |
Black, green and naturally black table olives (lab analysis) | Table olives Fruit · vs Before versus after heat treatment |
208 to 773 micrograms per kg in black olives, unchanged by heat; up to 24 micrograms per kg in green and naturally black olives before heating, rising to 1,200 after heating. Methods, limits and fundingOutcomes: Acrylamide content Limitations: Food analysis only; no health outcome. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Iwelomene 2025 Dietary sodium reduction and blood pressure: a dose-response meta-analysis in hypertensive and chronic kidney disease patients. Clin Kidney J · PMID 41635921 · DOI |
Meta-analysis |
1759 43 randomised trials, 51 groups; people with chronic kidney disease and/or high blood pressure |
Dietary sodium reduction 40 mmol a day (about 2.4 g of salt) less Varied · vs Usual sodium intake |
Lowering sodium by about 2.4 g of salt a day lowered systolic/diastolic pressure by 4.5/2.2 mmHg in kidney disease, 2.3/1.1 in hypertension and 0.3/0.1 in people without hypertension. Systolic -4.5 (CKD), -2.3 (HTN), -0.3 (no HTN) mmHg (CKD -5.8 to -3.1; HTN -3.0 to -1.6) Methods, limits and fundingOutcomes: Systolic and diastolic blood pressure Limitations: About sodium in general, not olives. Funding and conflicts: None declared. Read: abstract |
| Jalava 2011 Two cases of food-borne botulism in Finland caused by conserved olives, October 2011. Euro Surveill · PMID 22172330 · DOI |
Case report |
2 Two people who ate conserved olives stuffed with almonds |
Conserved stuffed olives Fruit |
Two people fell ill and one died. Clostridium botulinum type B and its toxin were found in the olives, which came from an Italian manufacturer and were withdrawn. Two cases, one death Methods, limits and fundingOutcomes: Botulism Limitations: Two cases. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Kerimi 2019 Nutritional implications of olives and sugar: attenuation of post-prandial glucose spikes in healthy volunteers by inhibition of sucrose hydrolysis and glucose transport by oleuropein. Eur J Nutr · PMID 29524000 · DOI |
Controlled trial |
Healthy volunteers in 7 crossover studies (number not given in the abstract), plus lab cell models | Oleuropein from olive leaves (water-soluble), capsules, solution, or naturally in olives Leaf extract; fruit Single meals · vs Placebo or control meal |
No effect on glucose after bread, including olives; lower glucose after 25 g sucrose with the solution; no effect with 50 g sucrose or glucose. Not given in the abstract Methods, limits and fundingOutcomes: Blood glucose after bread, glucose or sucrose Limitations: Healthy people, single meals, mostly a leaf extract. Funding and conflicts: One author is an employee of BioActor; another has received research funding from Nestle and the Florida Department of Citrus and sits on the Scientific Advisory Board of Nutrilite. Read: abstract |
| Lopez-Garcia 2023 Oral intake of Lactiplantibacillus pentosus LPG1 Produces a Beneficial Regulation of Gut Microbiota in Healthy Persons: A Randomised, Placebo-Controlled, Single-Blind Trial. Nutrients · PMID 37111150 · DOI |
Controlled trial |
39 39 healthy volunteers |
Lactiplantibacillus pentosus LPG1 capsules (strain isolated from table olive fermentation; not olives) 1 x 10^10 CFU a capsule daily (trial detail, not advice) 30 days · vs Dextrose placebo capsule |
Changed gut bacteria pattern, with more Parabacteroides and Agathobacter and less Prevotella; placebo group diversity fell. Methods, limits and fundingOutcomes: Stool bacteria by 16S sequencing Limitations: Single-blind; microbiome markers only; a probiotic capsule, not olives. Funding and conflicts: The record says no conflicts of interest and that funders had no role. Read: abstract |
| Montagano 2024 Health benefits of fermented olives, olive pomace and their polyphenols: a focus on the role of lactic acid bacteria. Front Nutr · PMID 39360269 · DOI |
Narrative review |
Mini-review | Fermented table olives and olive pomace Fruit and pomace |
Describes olives as a source of fibre and phenolics and as a plant-based fermented food of interest. The abstract does not give human outcome data. Methods, limits and fundingOutcomes: Potential role of lactic acid bacteria Limitations: Mini-review; the abstract does not say which studies it draws on. Funding and conflicts: No commercial relationships declared. Read: abstract |
| Racil 2015 The Pollen-Food Olive-Olive Syndrome. Tunis Med · PMID 26578052 |
Case report |
1 48-year-old woman with olive pollen allergy |
Olive fruit Fruit |
Palate itching and hives after eating olive fruit; oral challenge positive for olives and negative for olive oil. Single case Methods, limits and fundingOutcomes: Allergy Limitations: One patient. The authors say it is the fourth case reported. Funding and conflicts: Not stated. Read: abstract |
| Rocha 2020 Table olives and health: a review. J Nutr Sci · PMID 33354328 · DOI |
Narrative review |
Review of table olive composition and health claims | Table olives Fruit |
Table olives are rich in monounsaturated fat (mainly oleic acid), fibre and vitamin E, and hydroxytyrosol is the main phenolic compound in all types. The authors say there is a scarcity of in vitro, in vivo and human studies of table olives. Possible benefits are described as thought to be related to monounsaturated fat, vitamin E and hydroxytyrosol. Methods, limits and fundingOutcomes: Nutrient and bioactive content and assigned health benefits Limitations: Narrative review. Health effects are expected, not shown, in people. Funding and conflicts: Not stated in the abstract. Read: abstract |
| s-cdc-eid-botulism CDC Emerging Infectious Diseases: Botulism and Preserved Green Olives (2005, letter) · Source |
Case report |
Methods, limits and fundingRead: full-text | ||
| s-fda-sodium FDA: Sodium in Your Diet · Source |
Regulator n/a |
Methods, limits and fundingRead: full-text | ||
| s-nhs-babies NHS: Foods to avoid giving babies and young children · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-nhs-pregnancy NHS: Foods to avoid in pregnancy · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-nhs-salt NHS: Salt in your diet · Source |
Health agency n/a |
Methods, limits and fundingRead: full-text | ||
| s-usda-fdc-169094 USDA FoodData Central: Olives, ripe, canned (FDC 169094) and pickled green (FDC 169096) · Source |
Reference database n/a |
Methods, limits and fundingRead: summary-only |
What we do not know yet
- No human trial or cohort study of eating table olives for blood fats, blood pressure, diabetes or heart disease was found.
- Supplement and animal findings cannot be read as results for olives.
- Fermented olives and gut health have not been tested in people.
- How common olive fruit allergy is was not found.
- Pesticides, heavy metals and pregnancy guidance for olives were not researched.
How new research is added
New studies are found by a saved PubMed search and placed in a review queue before the page changes.
Lab markers
What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".
Metabolic 3
Total cholesterol
Decrease in trials
The total amount of cholesterol in the blood.
Low certaintyResults and what it means
Why it was measured
High cholesterol is a heart risk factor.
Statistical vs. clinical meaning
A small change in a blood marker with supplements. It is not shown for table olives, and it is not the same as fewer heart attacks.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 4 | Small fall in total cholesterol, SMD -0.19 (95% CI -0.37 to -0.01) | 14 human studies, 594 participants | Oleuropein, hydroxytyrosol or tyrosol supplements (not olives) |
Triglycerides
Decrease in trials
A type of fat carried in the blood.
Low certaintyResults and what it means
Why it was measured
High triglycerides are linked with heart risk.
Statistical vs. clinical meaning
Results varied a lot between studies. Supplements, not table olives.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 4 | Small fall in triglycerides, SMD -0.32 (95% CI -0.60 to -0.03); I2 73 percent | 14 human studies, 594 participants | Oleuropein, hydroxytyrosol or tyrosol supplements (not olives) |
Insulin (blood level)
Decrease in trials
The hormone that helps move sugar from the blood into cells.
Low certaintyResults and what it means
Why it was measured
Lower insulin can mean the body handles sugar more easily.
Statistical vs. clinical meaning
Large differences between studies. Supplements, not table olives.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 4 | Small fall in insulin, SMD -0.42 (95% CI -0.82 to -0.01); I2 78 percent | 14 human studies, 594 participants | Oleuropein, hydroxytyrosol or tyrosol supplements (not olives) |
Other 1
Blood glucose after a meal
No clear change in trials
How high blood sugar rises in the hours after eating.
Low certaintyResults and what it means
Why it was measured
Large spikes after meals are linked with poorer sugar control.
Statistical vs. clinical meaning
Olives themselves did not change blood sugar after bread in these tests.
Safety implication
None specific.
| Study | Result | People | Product |
|---|---|---|---|
| 10 | No effect on glucose from bread with oleuropein as capsules, solution or naturally in olives; lower glucose after 25 g sucrose with the leaf extract, none after 50 g sucrose or glucose | Healthy volunteers in crossover studies | Oleuropein from olives or olive leaf extract |
Safety
What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.
Main points to know 4
- Home-cured olives have caused botulism. In 2004, 28 diners in Italy reported symptoms (3 confirmed, 25 probable) after eating green olives preserved at home in salt water. A jar made at the same time had a pH of 6.2, above the 4.6 needed to stop the bacteria growing, and the salt level and pH were not controlled. In 2011, two people in Finland fell ill after eating bottled olives stuffed with almonds and one died; the toxin was found in the olives. Botulism needs emergency care. Case report 15 9
- Olives are salty. USDA lists 735 mg of sodium per 100 g of canned ripe olives and 1,556 mg per 100 g of pickled green olives (values from our earlier USDA summary). The NHS names olives among salty foods to eat less often or in small amounts. A 2026 meta-analysis found that cutting sodium lowers blood pressure most in people with kidney disease or high blood pressure. Authoritative guidance 19 16 8 20
- Olive pits can block the gut or be choked on. A 2024 case report describes a 70-year-old woman whose bowel was blocked by swallowed olive pits and who needed surgery. This is a single case. Case report 1
- Olive allergy is rare but reported. A 48-year-old woman with olive pollen allergy developed itching and hives after eating olive fruit; a challenge test was positive for olives and negative for olive oil. Another report describes anaphylaxis to olive fruit after pollen immunotherapy. Only the first abstract was read; the second has no abstract. Swelling of the face or throat or trouble breathing needs emergency help. Case report 13 2
Side effects 4
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Foodborne botulism from improperly cured olives Linked to home-preserved green olives in salt water (RR 5.2, 95% CI 1.4 to 19.8) and to a commercial jar of stuffed olives. Commercial products are usually controlled, but this shows it can happen. | Italy 2004 outbreak: 28 with symptoms among 66 diners interviewed (42 percent attack rate) | severe; 15 of 28 were admitted to hospital and 18 percent to intensive care in the Italian outbreak; one death in Finland Italy: after three weeks many still had constipation, blurred vision, dry mouth or trouble swallowing | Case report 15 9 |
| High salt intake raising blood pressure Sodium advice is about the whole diet. The NHS says adults should have no more than 6 g of salt a day. | Not established | depends on total diet Blood pressure fell when sodium was cut in trials | Systematic review 8 19 |
| Allergic reaction to olive fruit, from itching and hives to anaphylaxis Seen in people with olive pollen allergy. How common it is was not found. | Not established | mild to severe (single cases) Not stated | Case report 13 2 |
| Bowel obstruction from swallowed pits One adult case. | Not established | severe (one case needing surgery) Resolved after surgery | Case report 1 |
Liver
No liver injury from eating table olives was found in the sources read. LiverTox was not checked.
How often. No frequency was found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Olives supports liver health.
Medicines and supplements 2
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Blood pressure medicines and salt-restricted diets prescription | Not a drug interaction. Salty olives add sodium to the diet, and sodium raises blood pressure. | Matters for people told to limit salt, such as those with high blood pressure or kidney disease. | Authoritative guidance Moderate certainty 19 8 | If you were told to limit salt, count olives and ask your care team. |
| MAO-inhibitor medicines (tyramine foods) prescription | A 2000 analysis found tyramine and other biogenic amines in brined table olives after long brining, while fresh olive flesh had none. No source read links olives to an MAOI reaction. | Not established. The amounts and any effect in people were not found. | Other Not enough evidence 5 | If you take an MAO inhibitor, ask a pharmacist about fermented or aged foods, including olives. |
Who should check first 3
| Situation | Advice | Evidence |
|---|---|---|
| People told to limit salt (high blood pressure, kidney disease) | Count the sodium in olives and ask your care team. | Systematic review 8 19 |
| Olive pollen allergy or past reaction to olives | Ask an allergist before eating olives. Call emergency services for trouble breathing or swelling of the face or throat. | Case report 13 2 |
| Home curing of olives | Follow tested recipes with controlled salt and acidity. Do not eat olives from a bulging or off-smelling jar. A pH above 4.6 allows botulism bacteria to grow. | Case report 15 |
Overdose, product quality and regulators
Summary. No toxicity from commercially prepared olives as ordinary food was found in the sources read. The concerns are salt, improper curing, allergy and pits.
Animal. Not reviewed.
Overdose response. Not found.
Genotoxicity. Not researched.
Toxic or hazardous parts. The pit is not meant to be eaten; a bowel obstruction case is reported.
Acrylamide, a substance that forms in some heat-processed foods, has been measured in table olives. Biogenic amines build up in long-brined olives. Pesticides and heavy metals in olives were not researched.
Acrylamide. A 2023 analysis found 208 to 773 micrograms per kg in black table olives, and up to 1,200 micrograms per kg in green and naturally black olives after heat treatment. The abstract does not say what this means for health. 7
Biogenic amines. No biogenic amines were found in fresh olive flesh. Putrescine was highest in brined olives, and histamine, tyramine and tryptamine were found after 12 months of brining. Spoiled (zapatera) olives had higher amounts. 5
Home curing. The Italian outbreak olives were made with unstandardised salt and pH. A jar made at the same time had pH 6.2. 15
| Body | Action | Date |
|---|---|---|
| NHS (UK) (United Kingdom) | Salt advice: adults no more than 6 g of salt a day; eat salty foods including olives less often or in small amounts source | |
| FDA (US Food and Drug Administration) (United States) | Sodium Daily Value is less than 2,300 mg a day; Dietary Guidelines recommend adults limit sodium to less than 2,300 mg a day source | 2024-03-05 |
| NHS (UK) (United Kingdom) | Foods to avoid in pregnancy: olives are not mentioned source |
When to get medical help
- Double or blurred vision, drooping eyelids, trouble swallowing or speaking, dry mouth, or muscle weakness after eating preserved olives (possible botulism): call emergency services
- Trouble breathing, swelling of the lips, face or throat, or widespread hives after eating olives
- Severe belly pain, vomiting and no bowel movements after swallowing an olive pit
- Choking on an olive or pit
Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.
General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.
Frequently asked questions
Are olives good for you?
They are a source of fat, fibre and vitamin E, but also of salt. No study shows that eating table olives prevents disease. Most of the promising research is on olive oil or olive compounds.
Do olives lower cholesterol?
Not shown for olives. Supplements of olive compounds gave small falls in total cholesterol and triglycerides in a 2025 meta-analysis, with wide differences between studies.
Do olives lower blood pressure?
Are olives high in salt?
Do olives help blood sugar?
Olives eaten with bread did not change blood sugar in healthy volunteers. An olive leaf extract lowered it after a small sucrose dose only.
Are fermented olives a probiotic food?
Can olives cause botulism?
Can I be allergic to olives?
Are olive pits dangerous?
A swallowed pit blocked one woman's bowel and needed surgery. This is a single case, but pits are best removed.
Do olives contain acrylamide?
Yes, black olives had 208 to 773 micrograms per kg in one analysis. The abstract does not say what this means for health.
Do olives interact with medicines?
Are olives safe in pregnancy?
We found no official statement about olives. The NHS foods-to-avoid page does not mention them. Ask your midwife or doctor.
Explore by health goal
Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-26
- Last substantive update
- 2026-10-26
- How we research
- We started from our existing olive summary, searched PubMed for human trials, reviews, case reports and food analyses, and read NHS, FDA and CDC pages. Only abstracts were read for most studies. Nutrition figures come from our earlier USDA summary and were not re-checked today.
- How we rate evidence
- See "How we rate evidence" in the Evidence tab.
- Independence
- No product is promoted on this page. No affiliate links are shown.
Sources 20
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Bolanaki H, Pappas Gogos G, Karayiannakis AJ.. Intestinal Obstruction Due to Ingested Olive Pits.. Cureus. 2024. PMID 39650994. DOI 10.7759/cureus.73257. (abstract)
- Feo Brito F, Mur Gimeno P, Bartolome B, Castro A, Guerra F.. Anaphylaxis due to olive fruit after pollen immunotherapy.. J Investig Allergol Clin Immunol. 2011. PMID 21462812. (title-only)
- Frumuzachi O, Gavrilas LI, Vodnar DC, Rohn S, Mocan A.. Systemic Health Effects of Oleuropein and Hydroxytyrosol Supplementation: A Systematic Review of Randomized Controlled Trials.. Antioxidants (Basel). 2024. PMID 39334699. DOI 10.3390/antiox13091040. (abstract)
- Frumuzachi O, Kieserling H, Rohn S, Mocan A.. The impact of oleuropein, hydroxytyrosol, and tyrosol on cardiometabolic risk factors: a meta-analysis of randomized controlled trials.. Crit Rev Food Sci Nutr. 2025. PMID 39828996. DOI 10.1080/10408398.2025.2453090. (abstract)
- Garcia-Garcia P, Brenes-Balbuena M, Hornero-Mendez D, Garcia-Borrego A, Garrido-Fernandez A.. Content of biogenic amines in table olives.. J Food Prot. 2000. PMID 10643779. DOI 10.4315/0362-028x-63.1.111. (abstract)
- Gomez-Contreras A, Franco-Avila T, Miro L, Juan ME, Moreto M, Planas JM.. Dietary intake of table olives exerts antihypertensive effects in association with changes in gut microbiota in spontaneously hypertensive rats.. Food Funct. 2023. PMID 36861461. DOI 10.1039/d2fo02928f. (abstract)
- Holzle E, Becker L, Oellig C, Granvogl M.. Heat-Introduced Formation of Acrylamide in Table Olives: Analysis of Acrylamide, Free Asparagine, and 3-Aminopropionamide.. J Agric Food Chem. 2023. PMID 37647584. DOI 10.1021/acs.jafc.3c03457. (abstract)
- Iwelomene O, Gougeon A, Burnier M, Belot L, Sourd V, Fauvel JP, Granal M.. Dietary sodium reduction and blood pressure: a dose-response meta-analysis in hypertensive and chronic kidney disease patients.. Clin Kidney J. 2025. PMID 41635921. DOI 10.1093/ckj/sfaf340. (abstract)
- Jalava K, Selby K, Pihlajasaari A, et al.. Two cases of food-borne botulism in Finland caused by conserved olives, October 2011.. Euro Surveill. 2011. PMID 22172330. DOI 10.2807/ese.16.49.20034-en. (abstract)
- Kerimi A, Nyambe-Silavwe H, Pyner A, Oladele E, Gauer JS, Stevens Y, Williamson G.. Nutritional implications of olives and sugar: attenuation of post-prandial glucose spikes in healthy volunteers by inhibition of sucrose hydrolysis and glucose transport by oleuropein.. Eur J Nutr. 2019. PMID 29524000. DOI 10.1007/s00394-018-1662-9. (abstract)
- Lopez-Garcia E, Benitez-Cabello A, Arenas-de Larriva AP, Gutierrez-Mariscal FM, Perez-Martinez P, Yubero-Serrano EM, Garrido-Fernandez A, Arroyo-Lopez FN.. Oral intake of Lactiplantibacillus pentosus LPG1 Produces a Beneficial Regulation of Gut Microbiota in Healthy Persons: A Randomised, Placebo-Controlled, Single-Blind Trial.. Nutrients. 2023. PMID 37111150. DOI 10.3390/nu15081931. (abstract)
- Montagano F, Dell'Orco F, Prete R, Corsetti A.. Health benefits of fermented olives, olive pomace and their polyphenols: a focus on the role of lactic acid bacteria.. Front Nutr. 2024. PMID 39360269. DOI 10.3389/fnut.2024.1467724. (abstract)
- Racil H, Loukil M, Ferah Y, Cheikh Rouhou S, Chaouch N, Yaalaoui S, Chabbou A.. The Pollen-Food Olive-Olive Syndrome.. Tunis Med. 2015. PMID 26578052. (abstract)
- Rocha J, Borges N, Pinho O.. Table olives and health: a review.. J Nutr Sci. 2020. PMID 33354328. DOI 10.1017/jns.2020.50. (abstract)
- . CDC Emerging Infectious Diseases: Botulism and Preserved Green Olives (2005, letter). . . (full-text)
- . FDA: Sodium in Your Diet. . . (full-text)
- . NHS: Foods to avoid giving babies and young children. . . (full-text)
- . NHS: Foods to avoid in pregnancy. . . (full-text)
- . NHS: Salt in your diet. . . (full-text)
- . USDA FoodData Central: Olives, ripe, canned (FDC 169094) and pickled green (FDC 169096). . . (summary-only)
