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Olives are the fruit of the olive tree, Olea europaea, and they cannot be eaten straight from the branch: a bitter compound called oleuropein makes raw olives inedible until they are processed in lye, brine or both. The olives sold in stores are therefore a processed food, and that shapes their nutrition. In USDA data, canned ripe black olives have about 116 calories per 100 grams, mostly from monounsaturated fat, plus 735 milligrams of sodium (32% of the Daily Value); green olives are fattier and saltier. Below is how green and black olives are made, the USDA olive nutrition facts per olive, what research does and does not show about olives benefits, and why sodium and processing matter.
Peptide Labs does not sell olives or olive products. This article is general nutrition information, not medical advice.
Key Takeaways
- Raw olives are bitter from oleuropein; lye, brine and bacterial fermentation remove the bitterness.
- Spanish-style green olives are lye-processed and then fermented; Greek-style olives are fermented in brine without lye.
- California-style black ripe olives are darkened by air in a lye bath, fixed with an iron salt and heat-sterilized.
- USDA lists 735 milligrams of sodium per 100 g of ripe black olives and 1,556 milligrams for green olives.
- Most of the fat in olives is monounsaturated; green olives also supply vitamin E.
- Health research focuses mostly on olive oil and the Mediterranean diet, not on table olives themselves.
Why raw olives are bitter, and how olives are made edible
A 2020 food-science review explains that the olive fruit cannot be eaten directly from the tree because of oleuropein. Bitterness is removed either with an alkaline lye bath or by brining, salting, fermentation and acidification. During fermentation, lactic acid bacteria (mainly Lactobacillus plantarum and Lactobacillus pentosus) and yeasts break oleuropein down into non-bitter compounds such as hydroxytyrosol, and the lactic acid they make lowers the pH, which holds back spoilage organisms. Three main styles dominate world trade:
| Style | How bitterness is removed | Fermented? | Typical result |
|---|---|---|---|
| Spanish or Seville style green | Lye bath, rinse, then brine | Yes, by lactic acid bacteria | Firm green olives, often pitted or stuffed |
| Greek or natural style | Straight into brine; native microbes break down oleuropein | Yes, slowly | Brine-fermented olives, green or dark |
| California style black ripe | Lye bath with air to darken, iron salt to fix color | Not the main step | Mild, soft black olives in cans, heat-sterilized |
The California style explains why canned black olives taste so mild. According to a 2023 study from Spain’s Instituto de la Grasa, the olives are harvested green-yellow, stored in an acidified solution, darkened by a lye step with air washes over several days, then dipped in an iron salt solution (ferrous gluconate or lactate) to fix the black color. Because the finished pack is close to neutral pH, heat sterilization is mandatory for safety. So black ripe olives are not simply green olives left on the tree longer; the black color mostly comes from processing.
Olive nutrition: USDA values per olive
This table uses USDA SR Legacy entries, with FDC IDs and percent Daily Value (DV). Per-olive numbers are small, so it also shows ten olives and 100 grams for comparison.
| Olives (USDA FDC ID) | Amount | Calories | Fat (% DV) | Sodium (% DV) | Other notable nutrient |
|---|---|---|---|---|---|
| Ripe black, canned (169094) | 1 large olive, 4.4 g | 5 | 0.5 g (1%) | 32 mg (1%) | Iron 0.3 mg (2%) |
| Ripe black, canned (169094) | 10 large olives, 44 g | 51 | 4.8 g (6%) | 323 mg (14%) | Iron 2.8 mg (15%) |
| Ripe black, canned (169094) | 100 g | 116 | 10.9 g (14%) | 735 mg (32%) | Iron 6.3 mg (35%) |
| Green, pickled (169096) | 1 olive, 2.7 g | 4 | 0.4 g (1%) | 42 mg (2%) | Vitamin E 0.1 mg (1%) |
| Green, pickled (169096) | 10 olives, 27 g | 39 | 4.1 g (5%) | 420 mg (18%) | Vitamin E 1.0 mg (7%) |
| Green, pickled (169096) | 100 g | 145 | 15.3 g (20%) | 1,556 mg (68%) | Vitamin E 3.8 mg (25%) |
| Ripe black, jumbo to super colossal (169095) | 100 g | 81 | 6.9 g (9%) | 735 mg (32%) | Iron 3.3 mg (18%) |
In the USDA entry for ripe black olives, 7.65 of the 10.9 grams of fat per 100 grams is monounsaturated, the same fat family that dominates olive oil; saturated fat is 2.28 grams. Green olives carry more fat, more fiber (3.3 grams per 100 grams) and a quarter of the Daily Value for vitamin E, but more than twice the sodium. Black ripe olives stand out for iron, about a third of the Daily Value per 100 grams in USDA data. The iron salt used to fix their color may help explain that value, which is far higher than in the green olive entry. For other iron sources, see our foods high in iron guide. Copper is also notable, at 28% of the DV per 100 grams of ripe olives.
Because olives are fatty, they are more energy-dense than most fruits; our calorie-dense foods guide puts that in context. Olive oil is pressed from the fruit and has its own profile, covered in our olive oil guide.
Olives benefits: what the research shows
Most human research on olive health effects studies olive oil or the Mediterranean eating pattern, in which olives are one ingredient among many; our Mediterranean diet guide summarizes those trials and their limits. Trials testing table olives on their own are scarce, so cholesterol or heart claims made for olives borrow from olive oil research and go beyond what has been tested for the fruit.
- Polyphenols: olives contain phenolic compounds, and fermentation converts bitter oleuropein into hydroxytyrosol. Lab studies on these compounds are common; lab activity does not show an effect from eating olives. Our antioxidant foods guide explains why.
- Microbes: some lactic acid bacteria isolated from fermented table olives show probiotic traits in lab work. Canned black olives are heat-sterilized, and, as with other fermented foods, an undefined mix of microbes is not a probiotic.
- Leaves are different: olive leaf extract is a supplement made from the leaves, not the fruit; see our olive leaf extract guide.
Sodium in olives
Olives are packed in brine, and their sodium adds up. Against the FDA Daily Value of 2,300 milligrams, ten green olives supply about 18% of the DV and ten large black olives about 14% in USDA data, and stuffed, marinated or Greek-style olives can differ a lot by brand. Check the Nutrition Facts label, and if you are watching salt, our low-sodium foods guide and our sibling guide to pickles show how brined foods compare.
Acrylamide in black ripe olives
Because California-style black olives must be heat-sterilized, they can contain acrylamide, a compound that forms in some foods during high-heat processing. The 2023 Spanish study measured 15 commercial black ripe olive samples and found levels that varied more than tenfold between products, depending on cultivar and processing. Researchers are testing ways to lower it, and the study concerned black ripe olives specifically. This is a research and industry issue rather than a reason for alarm, but it is one more difference between olive styles.
Frequently Asked Questions
Are olives healthy?
Olives supply mostly monounsaturated fat, some fiber and, for green olives, vitamin E, but they are salty. Most health research is on olive oil and the Mediterranean diet, not table olives alone.
What is the difference between green and black olives?
Green olives are picked unripe and usually lye-processed and fermented. Canned black ripe olives are darkened by air in a lye bath and fixed with an iron salt.
Why can’t you eat olives straight from the tree?
Raw olives contain oleuropein, an intensely bitter compound. Lye, brine and fermentation break it down before olives are sold.
How much sodium is in olives?
USDA lists about 32 milligrams in one large black olive and 42 milligrams in one green olive, against a Daily Value of 2,300 milligrams. Brands vary, so read the label.
Do olives have probiotics?
Fermented olives contain lactic acid bacteria during processing, but canned olives are heat-sterilized and an undefined mix of microbes is not a probiotic.
Are olives high in calories?
Per olive, no: a large black olive has about 5 calories. Per 100 grams, olives have more calories than most fruits because of their fat.
Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Pickles: Nutrition, Sodium, Fermented vs Vinegar and Pickle Juice, Olive Oil Benefits: Research, Nutrition and Types of Olive Oil, Mediterranean Diet: What It Is, Food List and What the Research Shows, Types of Olives: Ripeness, Curing Styles and Olive Varieties.