Olives: a salt food with thin health evidence

Green olives in brine are a salt food first. Across 13 samples of green Manzanilla olives stuffed with pimiento, sodium ran from 1260 to 2200 mg per 100 g, and at the median five green olives carry about 310 mg. The jar you buy can sit anywhere in that range, so the sodium line on its label tells you more than any average. Fat is steadier, 11.1 to 14.8 g per 100 g. The health side is thin, and the reason matters. None of the research we found fed anyone actual olives. The one review of randomised trials that mentions them saw blood pressure fall with yogurt fortified with olive fruit polyphenols, gave no size for the drop in its abstract, and warned that the studies are few. The absorption study gave 12 volunteers supplements made from olives. The gut bacteria trial used a capsule of a bacterium first isolated from olive fermentation, and whether that strain lives in shop-bought olives has not been studied. So for olives as food, what we can stand behind is the salt and fat in the table.

The numbers, per 100 g

How much is actually in it

• Across 13 samples of green Manzanilla olives stuffed with pimiento, sodium ranged from 1260 to 2200 mg per 100 g (median 1540), a range of 940 mg, or 58% of the reported value of 1620, while fat stayed within 11.1-14.8 g. — Olives, green, Manzanilla, stuffed with pimiento (FDC 332791), USDA Foundation Foods (n = 13 samples) Evidence E source
  Sodium 1260-2200 mg per 100 g, median 1540, reported value 1620; fat 11.1-14.8 g, median 12.6
• US and UK tables for green olives agree within 18% on sodium (1620 against 1330 mg per 100 g) but differ by 47% on vitamin E (3.78 against 1.99 mg). — Olives, green, Manzanilla, stuffed with pimiento (FDC 332791) against Olives, green, in brine, drained (CoFID 14-340) (n = 1 USDA Foundation record (13 samples), 1 CoFID record) Evidence E source
  Sodium 1620 vs 1330 mg; vitamin E 3.78 vs 1.99 mg; fat 12.9 vs 11 g per 100 g

What a real portion looks like

• One olive weighs 4 to 5 g in the US dietary survey database and a cup 135 g, so at the Foundation median of 1540 mg sodium per 100 g five green olives carry about 310 mg. — household measures for Olives, green (FNDDS 2710089) and Olives, black (FNDDS 75510020) (n = 3 household measures per record) Evidence E source
  1 green olive 4 g; 1 black olive 5 g; 1 cup 135 g; quantity not specified 15 g

What your body absorbs

• Hydroxytyrosol, the olive antioxidant whose main dietary sources are table olives and olive oil, reached its peak in blood 30 minutes after a single dose in 12 healthy volunteers, and absorption rose with the dose (30.58 against 61.48 mg). — 12 healthy volunteers, single doses of two olive-derived watery supplements or fortified olive oil (n = 12) Evidence B source
  Plasma peak at 30 min; bioavailability increased with dose; main metabolites homovanillic acid, HT-3-O-sulphate, DOPAC

What cooking and storage change

• Listeria monocytogenes survived and grew in fermented green table olives, turning up in all of the study's own fermented batches older than 2 months and in one of the commercial heat-treated samples, whatever the cultivar, starter culture or brine acidity. — green table olives from different cultivars, Spanish-style and biological processing, stored 55 days to 18 months Evidence C source
  L. monocytogenes present in all of the study's own fermented batches older than 2 months and in 1 commercial thermally treated sample

What it does to your health

• A systematic review of 12 randomised trials of processed foods fortified with polyphenols (27-360 g of food and 32.5-850 mg of polyphenols a day) found that yogurt fortified with olive fruit polyphenols was among the foods that significantly lowered blood pressure. — 12 randomised controlled trials in adults, 2 to 52 weeks (n = 12 trials) Evidence A source
  Olive fruit polyphenol-fortified yogurt significantly lowered blood pressure; size not given in the abstract

Safety, limits and interactions

• In a small listeriosis outbreak in Ontario, opened canned black olives held 11 million Listeria per gram, yet challenge tests showed the olives did not support growth of the bacterium, which pointed to imitation crab meat as the source. — two previously healthy adults and foods from their refrigerator, Ontario (n = 2 patients) Evidence D source
  Canned black olives 1.1 x 10^7 cfu/g; olives did not support growth in challenge studies; patient strain matched crab meat

What people believe that the data does not support

• The EU rejected a health claim that olive polyphenols, from the fruit, mill waste water or oil, protect LDL cholesterol from oxidation and support good HDL (claim POL-HC-8370), so this wording may not be used on table olives in the EU. — EU register of nutrition and health claims Evidence E source
  Status non-authorised

Who this works differently for

• A 28-year-old man with olive pollen allergy developed palate itching and hives after eating olives 3 years later, while olive oil caused no symptoms, a pattern the authors named pollen-food olive-olive syndrome. — one 28-year-old man with olive pollinosis (n = 1) Evidence D source
  Positive prick-to-prick and specific IgE to olive fruit; open oral challenge with olive oil negative
• A 48-year-old woman with olive pollen allergy reacted to olives in an oral challenge but not to olive oil, which the authors report as only the fourth such case in the literature. — one 48-year-old woman, 5 years after diagnosis of olive pollinosis, Tunisia (n = 1) Evidence D source
  Oral provocation positive for olives, negative for olive oil

What is still unknown

• A lactic acid bacterium isolated from table olive fermentation, taken as a capsule of 10 billion CFU a day for 30 days by 20 healthy volunteers, shifted gut bacteria compared with 19 on placebo, raising Parabacteroides and Agathobacter and lowering Prevotella. — 39 healthy volunteers, capsule with breakfast for 30 days (n = 39) Evidence B source
  Increase in Parabacteroides and Agathobacter, decrease in Prevotella vs placebo; alpha diversity fell in the placebo group; capsule of an isolated strain, not olives; whether it survives in shop olives was not studied

The bottom line

The EU looked at the claim that olive polyphenols protect LDL cholesterol from oxidation and support good HDL, and rejected that wording, so it may not be used on table olives sold there. Even the basic numbers are less fixed than a table suggests. For green olives, US and UK tables agree within 18 percent on sodium and differ by 47 percent on vitamin E, 3.78 against 1.99 mg per 100 g. Food safety is where the evidence disagrees with itself. In one study Listeria survived and grew in fermented green table olives and turned up in all of the study's own fermented batches older than two months and in one of the commercial heat-treated samples, whatever the cultivar or the acidity of the brine. In a small Ontario outbreak, opened canned black olives carried 11 million Listeria per gram, yet in lab tests they did not let the bacterium grow, and the patients' strain matched imitation crab meat from the same fridge. Those are two small studies on different olives. Together they cannot tell you how risky an open jar in your fridge is. If you have an olive pollen allergy, two case reports describe people who reacted to eating olives while olive oil caused them no symptoms at all. Two cases show that it can happen and say nothing about how often. The section on who should be careful is thin for a reason. We found no evidence on olives and blood pressure medicine, kidney disease or pregnancy, and no study of what curing or storage does to them beyond the Listeria work. We are saying that plainly so the silence is not read as a green light. If your doctor has asked you to watch salt, olives belong in that conversation.

Sources

1. olv-b5-09 · reference dataset
   Olives, green, Manzanilla, stuffed with pimiento - Sodium, Na 1620.0 MG - range 1260.0-2200.0 (median 1540.0), samples 13 | Total lipid (fat) 12.9 G - range 11.1-14.8 (median 12.6), samples 13
   USDA FoodData Central, Foundation Foods record 332791, release 2026-04-30 · checked 2026-09-23
2. olv-b5-10 · reference dataset
   Olives, green, Manzanilla, stuffed with pimiento (FDC 332791) - Sodium 1620 MG - Vitamin E 3.78 MG - Fat 12.9 G | CoFID 14-340 Olives, green, in brine, drained, flesh and skin - Sodium 1330 mg - Vitamin E 1.99 mg - Fat 11 g
   USDA FoodData Central, Foundation record 332791, with UK CoFID 2021 (Public Health England, OGL v3.0) · checked 2026-09-23
3. olv-b5-11 · reference dataset
   Olives, black - FNDDS 75510020 - 1 olive 5 g - 1 cup 135 g - Quantity not specified 15 g | Olives, green (fdc 2710089) - 1 olive 4 g - 1 cup 135 g - Quantity not specified 15 g
   USDA FNDDS, Olives green (fdc 2710089) and Olives black (food code 75510020) · checked 2026-09-23
4. olv-b5-02 · randomised controlled blinded crossover trial
   Table olives and olive oils are the main dietary sources of hydroxytyrosol (HT), a natural antioxidant compound that has emerged as a potential aid in protection against cardiovascular risk. ... comparing two olive-derived watery supplements containing different doses of HT (30.58 and 61.48 mg of HT/dosage). ... Pharmacokinetic results showed that dietary HT administered through the food supplements is bioavailable and bioavailability increases with the administered dose. ... The maximum concentrations in plasma peaked 30 min after intake.
   Nutrients, 2023 · checked 2026-09-23
5. olv-b5-04 · prevalence survey of food samples
   Results demonstrated that L. monocytogenes can survive and grow in green table olives. L. monocytogenes was found in one of the commercial (thermally treated) samples analyzed and in all samples older than 2 months, irrespective of olive cultivar, lactic acid bacteria starter used, pH and titratable acidity of brine samples, or treatment applied.
   J Food Prot, 2004 · checked 2026-09-23
6. olv-b5-01 · systematic review of randomised controlled trials
   12 randomized controlled studies were included in the systematic review, with varying food intake amounts (27-360 g/day) and (poly)phenol doses (32.5-850 mg/day). ... Several foods, such as green tea extract-fortified rye bread and olive fruit (poly)phenol-fortified yogurt, significantly lowered blood pressure. ... caution is warranted due to the scarcity and limitations of existing studies.
   Crit Rev Food Sci Nutr, 2025 · checked 2026-09-23
7. olv-b5-05 · outbreak case report
   The three most heavily contaminated samples were the imitation crab meat, the olives and the salad which contained 2.1 x 109, 1.1 x 107 and 1.3 x 106 cfu g-1, respectively. ... Challenge studies performed with a pool of L. monocytogenes strains showed that imitation crab meat, but not olives, supported growth of the organism.
   Lett Appl Microbiol, 2000 · checked 2026-09-23
8. olv-b5-08 · regulation
   POL-HC-8370 Polyphenols from olive (olive fruit, olive mild waste waters or olive oil) Polyphenols are absorbed from olive oil in the intestine and metabolized there or in the liver, and have been shown to be able to bind LDL in vivo. They have demonstrated scavenging properties in vitro that ensure olive oil stability and explain their ability to protect LDL against oxidation. Contributes to good HDL cholesterol level. Polyphenols from olive have an antioxidant activity that may help protect LDL cholesterol and lipid oxidation Non-authorised
   EU Register on nutrition and health claims, claim POL-HC-8370, snapshot 2026-09-21 · checked 2026-09-23
9. olv-b5-06 · case report
   We report the case of a 28-year-old man who presented palatal itching and genaralized urticaria following ingestion of olive 3 years after being diagnosed with olive pollinosis. ... An open oral provocation test with olive oil did not cause symptoms.
   J Investig Allergol Clin Immunol, 2009 · checked 2026-09-23
10. olv-b5-07 · case report
    The aim is to report a rare case, it's the four case reported in the literature. ... The oral provocation test was positive for olives and negative for olive oil.
    Tunis Med, 2015 · checked 2026-09-23
11. olv-b5-03 · randomised placebo-controlled single-blind trial
    Lactiplantibacillus pentosus LPG1, a natural strain with probiotic potential isolated from table olive fermentations ... The trial was a randomised, placebo-controlled, single-blind study involving 39 healthy volunteers. Group A (n = 20) ingested one capsule/day of L. pentosus LPG1 containing 1 × 1010 UFC/capsule, while Group B (n = 19) received one capsule/day containing only dextrose (placebo). The capsules were taken during breakfast for 30 consecutive days. ... ingesting L. pentosus LPG1 modified the gut microbiota post-intervention, increasing the presence of Parabacteroides and Agathobacter, but reducing Prevotella.
    Nutrients, 2023 · checked 2026-09-23