E338 - Phosphoric acid

At a glance

• What it is: A food-grade inorganic acid also called orthophosphoric acid
• What it does: Lowers pH (acidity), adds a crisp “bite,” and ties up metal ions (sequestrant)
• Where it’s used: Especially common in colas and flavored soft drinks; also in some flavored waters, candies, and shelf-stable drinks
• Other names: E338, orthophosphoric acid
• Dietary notes: Mineral-based; suitable for vegetarian and vegan diets

Why is phosphoric acid added to food?

Food makers use phosphoric acid to adjust pH, which keeps products stable, safe, and consistent in taste. It gives a clean, sharp tartness that pairs well with caramel flavors in colas, and it acts as a sequestrant, meaning it binds metal ions that can speed up oxidation and cause off-colors or off-flavors.¹

What foods contain phosphoric acid?

You’ll most often find phosphoric acid in:

• Colas and many “dark” soft drinks
• Some clear or flavored sodas and energy drinks
• Certain ready-to-drink teas, flavored waters, and sports beverages
• A few candies, syrups, and shelf-stable drink concentrates

Always check the ingredient list; labeling is required and it will appear as “phosphoric acid.”

What can replace phosphoric acid?

• For tartness or pH control: Other food acids such as citric acid, malic acid, lactic acid, or acetic acid can provide acidity, though the flavor profile will differ.
• For binding metals (sequestration) or buffering: Phosphate salts like sodium phosphates, disodium diphosphate, or triphosphates are sometimes used instead, depending on the recipe.

How is phosphoric acid made?

Commercially, phosphoric acid is produced by two main routes. The “wet process” reacts phosphate rock with sulfuric acid, while the “thermal process” burns elemental phosphorus to phosphorus pentoxide and hydrates it to the acid; the thermal route yields high-purity material. Food-grade phosphoric acid comes from processes and purification steps designed to meet strict quality specifications.²

Is phosphoric acid safe to eat?

In the United States, phosphoric acid is permitted in food and appears on the Food Additive Status List; it is considered safe when used in line with good manufacturing practice.³ In the European Union, E338 is authorized as a food additive; the European Food Safety Authority (EFSA) set a group acceptable daily intake (ADI) for phosphates (including E338) of 40 mg per kilogram of body weight per day, expressed as phosphorus.¹ Like other acidic drinks, frequent sipping of soft drinks can contribute to dental enamel erosion over time; enjoying them in moderation and with meals helps reduce risk.⁴

Does phosphoric acid have any benefits?

Phosphoric acid’s benefits are technological: it sharpens flavor, stabilizes color, and helps keep products shelf-stable by managing pH. By tying up trace metals, it can slow reactions that lead to haze, off-flavors, and nutrient losses in drinks.

Who should avoid phosphoric acid?

• People with chronic kidney disease (CKD) or those advised to follow a low-phosphorus diet should limit phosphate sources, including foods and drinks acidified with phosphoric acid.⁵
• Anyone prone to dental erosion may wish to limit acidic beverages and practice good oral hygiene (rinse with water after drinking, avoid frequent sipping).⁴
• Individuals who are sensitive to acidic foods and drinks (for example, due to reflux) may prefer milder acidulants like citric acid or malic acid.

Myths & facts

• Myth: “Phosphoric acid in soda will dissolve a tooth overnight.” Fact: Household sodas are far less acidic than concentrated lab acids; enamel erosion is a gradual process linked to frequent exposure and poor oral hygiene.
• Myth: “Only dark colas use phosphoric acid.” Fact: Many colas do, but some clear sodas, energy drinks, and flavored waters also use it for pH control and taste.
• Myth: “Food-grade phosphoric acid is the same as industrial chemicals.” Fact: It’s the same compound, but food-grade material must meet strict purity standards suitable for consumption.

Phosphoric acid in branded foods

Many well-known colas, diet colas, and other carbonated soft drinks list “phosphoric acid” on the label. It can also appear in some ready-to-drink teas, flavored waters, and sports or energy beverages. Check the ingredients panel—its presence varies by flavor and product line.

References

Footnotes

1. Re-evaluation of phosphoric acid–phosphates–di-, tri- and polyphosphates (E 338–452) as food additives — European Food Safety Authority (EFSA). https://www.efsa.europa.eu/en/efsajournal/pub/5674 ↩ ↩²

2. Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers (LVIC-AAF), Best Available Techniques Reference Document — European Commission JRC. https://eippcb.jrc.ec.europa.eu/reference/lvic-aaf ↩

3. Food Additive Status List — U.S. Food and Drug Administration (FDA). https://www.fda.gov/food/food-additives-petitions/food-additive-status-list ↩

4. Tooth erosion (dental erosion) — MedlinePlus, National Institutes of Health (NIH). https://medlineplus.gov/ency/article/002369.htm ↩ ↩²

5. Phosphorus and chronic kidney disease — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH. https://www.niddk.nih.gov/health-information/kidney-disease/ckd-nutrition/phosphorus ↩