E170II - Calcium hydrogen carbonate

At a glance

Here’s a brief overview of what E170II does and where you might find it.

• What it is: Calcium hydrogen carbonate, also called calcium bicarbonate; it exists only dissolved in water.
• What it does: Acts as a mild alkalinity regulator and pH buffer; contributes calcium.
• Where it appears: Naturally in hard water; sometimes present in mineral waters and other water-based drinks.
• Stability: Loses carbon dioxide on warming or standing, reverting to insoluble calcium carbonate.¹
• Safety: Carbonate and bicarbonate salts have long food use; calcium carbonate (E170) is considered safe at reported uses by EU and U.S. authorities.²³

Why is Calcium hydrogen carbonate added to food?

Manufacturers may rely on calcium hydrogen carbonate in solution to fine‑tune mineral balance and alkalinity in water-based products, which can soften sharp acidity and support a clean, “fresh water” taste. In doing so, it also adds a small amount of dietary calcium.²

What foods contain Calcium hydrogen carbonate?

You’re most likely to encounter E170II in:

• Bottled mineral and spring waters that naturally contain bicarbonate minerals
• Carbonated waters and seltzers where minerals are adjusted for flavor balance

Because calcium hydrogen carbonate exists only in solution, it may not appear as a separate powdered ingredient; it forms when water contains dissolved carbon dioxide and calcium and can revert to calcium carbonate if the water is heated or degassed.¹

What can replace Calcium hydrogen carbonate?

Alternatives depend on the goal:

• To add calcium without affecting carbonation: Calcium carbonate (E170i)
• To buffer acidity in beverages: Sodium bicarbonate (E500ii) or sodium citrates (E331)
• To brighten and acidify instead of alkalizing: Citric acid (E330)

How is Calcium hydrogen carbonate made?

In practice, it’s made in place (in situ): carbon dioxide dissolves into water and reacts with calcium carbonate (limestone/chalk) to form dissolved calcium hydrogen carbonate. When the water warms or loses carbon dioxide, the reaction runs backward and insoluble calcium carbonate precipitates—this is the familiar “scale” from hard water.¹

Is Calcium hydrogen carbonate safe to eat?

Calcium and bicarbonate ions are normal parts of foods and drinking water. The European Food Safety Authority (EFSA) concluded there is no safety concern for calcium carbonate (E170) at reported uses and exposure levels, and bicarbonate/carbonate salts have a long history of use in foods.² In the United States, calcium carbonate is “Generally Recognized as Safe” (GRAS) when used within good manufacturing practice.³

Does Calcium hydrogen carbonate have any benefits?

• It contributes a small amount of calcium, an essential mineral important for bones, muscles, and nerves.⁴
• In drinks, mild alkalinity can smooth sour notes and stabilize flavor. These are modest, product‑dependent effects rather than clinical benefits.

Who should avoid Calcium hydrogen carbonate?

• People who must limit calcium intake (for example, certain kidney conditions) should consider total dietary calcium from all sources, including mineral waters, and seek medical advice as needed.⁴
• Calcium can interfere with the absorption of some medicines if taken at the same time; follow healthcare guidance on timing of doses.⁴

Myths & facts

• Myth: It’s the same as chalk floating in water. Fact: Calcium hydrogen carbonate is dissolved; if carbon dioxide escapes or the water is heated, solid chalky scale (calcium carbonate) can form.
• Myth: It adds fizz to drinks. Fact: Carbon dioxide provides fizz; bicarbonate mainly affects mineral balance and pH.
• Myth: It’s a preservative. Fact: Its role is buffering and mineralization, not preservation.

Calcium hydrogen carbonate in branded foods

On labels, you may see “calcium hydrogen carbonate,” “calcium bicarbonate,” or “E170ii,” especially on European products that list mineral composition. In many cases, companies adjust water minerals so the bicarbonate forms naturally in solution rather than adding a dry ingredient.

References

Footnotes

1. Hardness in water — U.S. Geological Survey. https://www.usgs.gov/special-topics/water-science-school/science/hardness-water ↩ ↩² ↩³

2. Scientific Opinion on the re-evaluation of calcium carbonate (E 170) as a food additive — EFSA Journal. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2011.2318 ↩ ↩² ↩³

3. 21 CFR 184.1191 Calcium carbonate — U.S. Food and Drug Administration. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-184/section-184.1191 ↩ ↩²

4. Calcium Fact Sheet for Health Professionals — National Institutes of Health, Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Calcium-Consumer/ ↩ ↩² ↩³