Phosphoric acid

A colorless, sour-tasting acid used in tiny amounts to sharpen flavor, control pH, and help preserve foods and drinks (especially colas).

Should I eat Phosphoric acid?

Used in tiny amounts, phosphoric acid is generally safe and helps control acidity and flavor. The main practical risks come from frequent intake of very acidic sodas (tooth erosion) and a higher total phosphate load—especially for children and people with kidney disease.

Summary

Phosphoric acid (E338) is a common acidulant in sodas and processed foods that adds a clean, sharp tartness and tightly controls pH at very low levels. FDA considers it GRAS when used as intended, and EFSA set a group ADI for all phosphate additives of 40 mg/kg/day as phosphorus, noting some children can exceed this. Dental studies show low‑pH beverages are erosive to enamel, particularly with frequent sipping. Observational research links heavy soft‑drink intake to poorer bone measures, but causation is unproven and likely involves multiple lifestyle factors. If you drink soft drinks, limit frequency, rinse with water after acidic beverages, and consider options acidified with non‑phosphate acids if you are monitoring phosphorus intake.

Key Research Points

Acidic sodas can erode teeth

Frequently sipping low‑pH drinks, including those acidified with phosphoric acid, can wear down tooth enamel; limit frequency and rinse with water after acidic beverages.

Watch total phosphate intake

EFSA set a group acceptable daily intake (ADI) of 40 mg/kg body weight per day as phosphorus for all phosphate additives; some high consumers—especially children—may exceed this level.

Extra caution with kidney disease

People with chronic kidney disease (CKD) have reduced ability to excrete phosphorus; EFSA notes the ADI does not apply to moderate–severe CKD, so phosphorus additives should be limited.

Overview

What is it?

Source: Phosphate rock-derived phosphoric acid

Method: Acid digestion and purification

Processing Level: 9 / 10

Why is it used?

Purpose: Acidity regulator used to control pH and add tartness.

Commonly found in: Cola drinks; Soft drinks; Processed meats; Cheese; Baked goods

Why manufacturers choose it: Delivers a sharp, neutral tartness and precise pH control at low cost.

Origin

Commercial phosphoric acid rose with the phosphate fertilizer industry in the 19th–20th centuries. Most is made by reacting crushed phosphate rock (apatite) with sulfuric acid (the “wet process”), yielding phosphoric acid and gypsum; a smaller portion is made by burning elemental phosphorus and hydrating the resulting phosphorus pentoxide (the “thermal process”). While thermal acid historically supplied food and beverage uses due to high purity, advances in purification now allow wet-process acid to be refined for food-grade applications.

Process: Acid digestion and purification

Steps

1. Digest: React ground phosphate rock with sulfuric acid to form phosphoric acid slurry and calcium sulfate (gypsum) by-product.

2. Separate: Filter off gypsum solids; collect crude phosphoric acid solution.

3. Purify: Remove impurities (e.g., by crystallization/solvent extraction, clarification, and decolorization) to food-grade specs.

4. Concentrate: Evaporate water to typical 75–85% H3PO4 for shipment.

5. Dilute for use: Meter small amounts into foods/beverages to reach target pH and flavor.

Chemicals

Sulfuric acid (wet process)

Research & Safety

Potential Concerns

The strongest near‑term concern is dental erosion from repeated exposure to very acidic beverages. As a highly refined phosphate additive, phosphoric acid contributes phosphorus without other nutrients, so high intake across multiple processed foods can raise total phosphate load. EFSA’s group ADI is 40 mg/kg body weight per day as phosphorus, and some children with high processed‑food and soda intake may exceed it. People with chronic kidney disease should minimize phosphorus additives because their bodies clear phosphorus less effectively and the ADI does not apply to them.

Potential Benefits

No demonstrated nutrimental benefit

Digestive Effects

Most people tolerate the tiny amounts used in foods without stomach issues. Large volumes of acidic drinks may aggravate heartburn or reflux in sensitive individuals. If you notice throat or stomach irritation after acidic beverages, spacing them with meals, avoiding prolonged sipping, and rinsing with water may help. Dental sensitivity can be a sign of enamel wear from acidity; discuss with your dentist if you frequently consume soft drinks.

Limit Consumption

Children and teens who drink multiple soft drinks daily are more likely to exceed EFSA’s phosphate ADI and face higher dental‑erosion risk due to frequent low‑pH exposure. People with chronic kidney disease should limit phosphorus additives because reduced kidney function impairs phosphorus removal, and EFSA states the ADI does not apply to moderate–severe CKD. Individuals with active dental erosion or high cavity risk should minimize frequent acidic beverage intake and avoid prolonged sipping. Those with reflux may find very acidic drinks worsen symptoms; reducing frequency and volume can help.

Fact Sheet

Regulatory Status

US FDA: GRAS when used in accordance with GMP (21 CFR §182.1073).

EU Status: E338; EFSA group ADI for phosphates = 40 mg/kg bw/day as phosphorus; some groups may exceed.

Codex INS: INS 338 (acidity regulator, sequestrant).

JECFA ADI: Group MTDI 70 mg/kg bw as phosphorus from all sources.

ESG & Sustainability

Environmental Footprint: Wet-process production generates phosphogypsum and acidic waters containing fluoride and phosphorus that require management.

Sustainability: Ongoing research into cleaner processes and gypsum reutilization; thermal route is higher energy.

Animal Welfare: Not directly applicable (chemical additive).

Carbon Footprint: Thermal (elemental P) process is energy-intensive (electric furnace ~2000 °C); wet-process has lower energy but waste challenges.

Allergens and Diet

Allergen Status: None

Diet Compatibility: Vegan, Vegetarian, Kosher, Halal, Gluten-free, Dairy-free, Low-FODMAP, Keto, Paleo, Non-GMO

Natural Alternatives

Lactic acid

Source: Fermentation of carbohydrates by lactic acid bacteria

Processing Level: Moderate

Common Uses: Pickles, yogurt drinks, sauces

Replacement Benefit: No phosphorus; gentle sourness; well-studied fermentation acid.

Why it's not used: Lactic acid’s flavor can be dairy/malty; phosphoric acid gives a neutral ‘bite’ and strong pH control at low doses.

Tartaric acid

Source: Wine by-product (grape lees) or synthesis from tartar

Processing Level: Moderate

Common Uses: Beverages, confections, leavening

Replacement Benefit: No added phosphorus; occurs naturally in grapes/wine.

Why it's not used: Tartaric acid has a distinctive tart–fruity note and higher cost; phosphoric acid is neutral in flavor and economical.

Citric acid

Source: Fermentation of sugar substrates by Aspergillus (citrus fruits naturally contain it)

Processing Level: Moderate

Common Uses: Beverages, candies, jams, dressings

Replacement Benefit: Naturally occurring in foods and widely tolerated; contributes fruity sourness and buffering without phosphorus load.

Why it's not used: Citric acid adds citrus/fruity notes; where a ‘clean’, non-fruity tartness is needed (colas), phosphoric acid matches the classic profile and may be cheaper.