Are Canned Olives High in Iron? Separating Fact From Fiction

December 22, 2025 •

4 min read

Ripe, canned black olives contain significantly more iron than their green counterparts, with 100 grams of black olives offering over 6 mg of iron. This surprising fact challenges common perceptions, so are canned olives high in iron? The answer depends heavily on the olive's color, its stage of ripeness, and specific processing methods.

Quick Summary

Canned black olives are a good source of iron, containing substantially more than green olives. The iron content is influenced by the variety, ripeness, and canning process, which often involves adding iron compounds.

Key Points

Black Olives Are Iron-Rich: Ripe, canned black olives are a good source of iron, containing over 6 mg per 100 grams, whereas green olives have much less.
Color Affects Iron Content: The significant difference in iron levels between black and green olives is due to ripeness and the specific processing methods used.
Processing Adds Iron: Canned black olives are often treated with ferrous gluconate, an iron salt, to fix their dark color, which artificially increases their iron content.
Iron is Less Absorbable: The iron in olives is non-heme iron, a plant-based form that is not as easily absorbed by the body as the heme iron found in meat.
Enhance Absorption with Vitamin C: To maximize the non-heme iron absorption from olives, pair them with foods rich in vitamin C, like bell peppers or citrus fruits.
Consider Sodium Content: Canned olives, particularly the green variety, are high in sodium due to their brining process, which is an important factor for managing salt intake.

The Nutritional Tale of Two Olives: Black vs. Green

When considering the iron content of canned olives, the most crucial distinction is color, which indicates ripeness and processing. This single factor creates a dramatic difference in the final nutritional profile. Canned black olives, also known as ripe olives, undergo a unique canning process that intentionally enriches their iron content, while green olives, harvested unripe, do not.

Why Black Olives Become Iron-Rich

What makes canned black olives a notable source of iron is a specific step in their industrial processing. To achieve a uniform, dark black color, producers treat the olives with ferrous gluconate, an iron salt that acts as a color stabilizer. This additive binds with the olives' naturally occurring phenolic compounds, creating a dark, stable color and simultaneously boosting the total iron content. The iron content can be significant, with some sources reporting around 6.28 mg per 100g serving, representing a substantial portion of the recommended daily intake.

The Lower Iron Content of Green Olives

In stark contrast, green olives are picked before they are fully ripe and typically cured in brine or lye without the addition of iron salts. As a result, their iron levels remain very low. According to nutritional data, a 100g serving of canned green olives contains only about 0.49 mg of iron, making them an insignificant source of this mineral. This difference highlights how processing can alter a food's nutritional value dramatically, underscoring the importance of understanding how our food is prepared.

The Iron in Olives: Bioavailability and Absorption

The iron found in canned olives is non-heme iron, the type present in all plant-based foods. Unlike the heme iron found in animal products, which is readily absorbed by the body, non-heme iron's absorption is less efficient and can be influenced by other dietary factors. For individuals, particularly those following vegetarian or vegan diets, maximizing non-heme iron absorption is a key consideration for maintaining adequate iron levels.

Maximizing Iron Absorption from Olives

Fortunately, there are simple dietary strategies to improve the absorption of non-heme iron from foods like olives:

Pair with Vitamin C: Consume olives alongside vitamin C-rich foods. Vitamin C can significantly increase non-heme iron absorption. Think of adding olives to a salad with bell peppers or tomatoes, or enjoying them with a side of citrus fruit. The vitamin C helps to capture the iron and store it in a form the body can absorb more easily.
Avoid Competing Compounds: Certain compounds can hinder iron absorption, including phytates (found in grains and legumes), tannins (in tea and coffee), and calcium. It is best to avoid drinking coffee, tea, or milk with a meal rich in non-heme iron.
Use Cast Iron Cookware: Cooking in a cast iron pan can leach small amounts of iron into your food, boosting your intake. While the effect is subtle, it's an easy way to increase your overall iron exposure.

Beyond Iron: Other Health Benefits of Olives

While their iron content is notable, especially for the black variety, olives offer a host of other health benefits that make them a valuable part of a balanced diet.

Healthy Fats: Olives are rich in healthy monounsaturated fats, particularly oleic acid, which is known for its heart-protective properties.
Antioxidants: Olives are packed with antioxidants like vitamin E and polyphenols. These compounds help combat inflammation and oxidative stress, potentially reducing the risk of chronic diseases.
Dietary Fiber: As a fruit, olives provide a source of dietary fiber, which is important for digestive health.
Vitamins and Minerals: In addition to iron, olives contain other essential minerals like copper and calcium.

Comparison of Black vs. Green Olives

To provide a clear overview, here's a comparison of the key nutritional differences between canned black and green olives, based on a 100g serving.


Nutrient	Canned Black Olives	Canned Green Olives
Iron Content	High (Approx. 6.28 mg)	Low (Approx. 0.49 mg)
Sodium Content	Lower (Approx. 735 mg)	Higher (Approx. 1,556 mg)
Processing	Treated with ferrous gluconate	Typically cured in brine or lye
Ripeness	Ripe	Unripe
Fat Content	Lower (Approx. 10.9 g)	Higher (Approx. 15.32 g)

Conclusion: The Final Verdict on Canned Olives and Iron

Ultimately, the question of "are canned olives high in iron?" is nuanced. The answer is a definitive "yes" for canned ripe black olives, which are specifically processed to stabilize their dark color with an iron compound, substantially increasing their iron content. However, the same cannot be said for canned green olives, which remain a poor source of this mineral. When relying on olives as a dietary source of iron, it is crucial to choose black olives and, to maximize absorption, pair them with vitamin C-rich foods. While canned olives contain non-heme iron, which is less efficiently absorbed than heme iron from animal sources, they can still be a valuable contributor to a balanced, iron-rich diet, especially for those who consume limited or no meat. Beyond the iron boost, both black and green olives offer a variety of other health benefits, including healthy fats and antioxidants, making them a nutritious and flavorful addition to many meals. For more detailed information on iron and its health benefits, you can consult the NIH Office of Dietary Supplements.(https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/)

Frequently Asked Questions

Canned black olives are significantly higher in iron than green olives due to their ripeness and the use of iron-based color fixatives during processing.

Yes, the canning process for black olives often involves adding ferrous gluconate, a food additive that helps stabilize the black color and increases the iron content.

The iron in canned olives is non-heme iron, the type found in plant-based foods, which is not as easily absorbed by the body as heme iron from meat.

Pair your olives with foods high in vitamin C, such as tomatoes, citrus, or bell peppers, as vitamin C enhances non-heme iron absorption.

Canned black olives can contribute to iron intake for vegans and vegetarians, especially when paired with vitamin C sources, though they contain the less-absorbable non-heme iron.

On a per-gram basis, canned black olives can have a comparable or even higher iron concentration than spinach, depending on the olive variety and processing.

Yes, the iron salts like ferrous gluconate are approved food additives used to fix the color of canned olives and are safe for consumption within regulated limits.

Black olives generally have higher iron content and lower sodium than green olives, while green olives often have a higher fat content.