What Common Food Item Has Calcium Carbonate?

December 22, 2025 •

3 min read

Over 40% of Americans may not get enough calcium from their diet, prompting many food manufacturers to add calcium carbonate as a fortifying agent. This common food additive helps ensure consumers receive this vital mineral, but what common food item has calcium carbonate as an ingredient?

Quick Summary

Calcium carbonate is added to many fortified foods, including plant-based milks, breakfast cereals, and juices, to boost calcium content and improve texture. It is also derived from natural sources like shells for supplements.

Key Points

Found in Fortified Foods: Calcium carbonate is widely added to products like plant-based milks, cereals, and juices to boost calcium content.
Used as a Food Additive: It functions as an anticaking agent in powders, a stabilizer in some dairy products, and a firming agent in canned goods.
Derived from Natural Sources: The compound is naturally abundant in eggshells and oyster shells, which are processed into food-grade powder.
Check the Label: To identify calcium carbonate, look for the ingredient name or the E number E170 on food labels.
A Common Supplement: Besides food, it is a very common and effective dietary supplement and antacid, known for its high elemental calcium content.
Shake Plant-Based Milks: The presence of calcium carbonate is why many plant-based milks require shaking before pouring, as the mineral can settle at the bottom.

Fortified Foods: The Primary Source of Calcium Carbonate

Many consumers unknowingly consume calcium carbonate on a regular basis through fortified foods and beverages. Food manufacturers strategically add this compound to increase the nutritional content of products, making it easier for people to meet their daily calcium requirements. This practice is especially beneficial for individuals with dietary restrictions, such as those who are lactose intolerant or follow a vegan diet, as it provides a non-dairy source of calcium.

Milk Alternatives

One of the most common applications of calcium carbonate is in plant-based milk alternatives. Soy milk, almond milk, and rice milk are frequently fortified with calcium to match the nutritional profile of dairy milk. To ensure even distribution, the calcium carbonate is blended into the beverage during processing. When you notice separation in a carton of plant-based milk, where a white, chalky substance settles at the bottom, you are seeing the calcium carbonate settling out of the liquid. A simple shake of the carton is all that is needed to mix it back in.

Breakfast Cereals and Grains

Another significant category of fortified foods containing calcium carbonate is breakfast cereals. Many ready-to-eat cereals and cereal bars are enriched with this mineral to provide a convenient and nutritious start to the day. Similarly, some flour products, biscuits, and crackers also have calcium carbonate added during production. This helps to not only improve the nutritional value but can also function as a dough regulator in baked goods.

Other Processed Foods and Drinks

Calcium carbonate also serves multiple technical roles in food production beyond simple fortification.

Anticaking Agent: In powdered or granulated foods, such as flour, spices, and powdered drink mixes, it prevents clumping.
Firming Agent: It is used to maintain the texture of fruits and vegetables in canned products, preventing them from becoming too soft during processing.
Acid Neutralizer: In certain foods and beverages, it can be used to regulate pH levels and balance flavors.

Natural Sources Used in Food Production

While most direct human consumption of calcium carbonate comes from fortified items, the compound itself is derived from natural sources. It's an abundant compound found in the Earth's crust in limestone, marble, and chalk.

Oyster Shells and Eggshells

Perhaps the most recognizable natural source of calcium carbonate is in the shells of marine organisms and eggs. Oyster shells, in particular, are a popular, sustainable source for producing calcium supplements and food-grade powders. These shells are cleaned, crushed, and refined to create a high-purity, low-contamination powder that is then used for fortification. While these shells themselves are not typically eaten directly, the processed powder derived from them is a valuable component of the food supply chain.

Calcium Carbonate vs. Calcium Citrate

When comparing common calcium additives, it's helpful to understand the differences between calcium carbonate and calcium citrate, especially in supplements and fortified foods. Both are effective sources of elemental calcium, but they have distinct characteristics.


Feature	Calcium Carbonate	Calcium Citrate
Elemental Calcium Content	Approximately 40%	Approximately 21%
Best Absorption	Better absorbed when taken with food due to stomach acid.	Can be absorbed efficiently at any time, with or without food.
Cost	Generally more inexpensive.	More expensive than calcium carbonate.
Best For	Most people taking a supplement, especially with a meal.	Individuals with low stomach acid (e.g., older adults or those taking acid blockers).

Checking Your Labels for Calcium Carbonate

To see if a food item contains calcium carbonate, simply check the ingredient list on the nutrition label. It may be explicitly listed as “calcium carbonate” or as a food additive with a European E number, E170. This information provides transparency, allowing consumers to make informed choices about their dietary intake and to identify potential sources of calcium if they are looking to increase their consumption.

Conclusion

Calcium carbonate is a common and widely used food additive, primarily used for nutritional fortification and texture improvement. It is most frequently found in products intended to provide a high amount of calcium, such as plant-based milks, breakfast cereals, and certain juices. While its natural form is present in shells, it is the refined, food-grade powder that becomes an ingredient in our packaged foods. Understanding its role in food science allows consumers to appreciate how common food items deliver this essential mineral and to make informed choices about their health. For those seeking additional information on this supplement, the MedlinePlus guide offers further details.

Frequently Asked Questions

Plant-based milks (soy, almond, rice), many breakfast cereals, orange juice, and some canned foods like salmon or vegetables are frequently fortified with calcium carbonate.

Yes, food-grade calcium carbonate is generally recognized as safe (GRAS) by regulatory bodies when used as a food additive. The amounts used are minuscule and beneficial for those who need to supplement their calcium intake.

When used in appropriate amounts for fortification, calcium carbonate has a minimal impact on a food's taste. It is primarily used for its nutritional and functional properties, like improving texture or stability.

The separation seen in plant-based milks is often due to the insoluble nature of calcium carbonate, which settles at the bottom over time. Shaking the container redistributes the mineral throughout the liquid.

The easiest way is to read the ingredient list on the product label. It will typically be listed as 'calcium carbonate'. In Europe, it might be identified by the food additive number E170.

The calcium carbonate is fundamentally the same compound, but the dosage and absorption can differ. Supplemental calcium carbonate is more potent and often requires a meal for best absorption, while fortified foods provide smaller, more easily absorbed amounts.

While eggshells are a natural source of calcium carbonate (approximately 95% of their dry weight), they are not a common food item for direct consumption. Instead, eggshells can be processed into a fine powder for use in supplements.