E501(ii) – Potassium hydrogen carbonate | bladder tumour concern and food uses

Quick analysis summary about E501(ii) – Potassium hydrogen carbonate food additive

Bottom line about E501(ii)

E501(ii) potassium hydrogen carbonate, also called potassium bicarbonate, is graded ORANGE – SOME CONCERNS. Very high long-term dietary doses caused bladder lesions and tumours in rats, although normal human dietary exposure has not been shown to cause cancer.

Why this grade for E501(ii)

Rats fed 2% or 4% potassium bicarbonate developed urinary-bladder changes, and prolonged 4% exposure produced papillomas and carcinomas.[1,2] The pattern is consistent with altered urinary chemistry at extreme exposure, but the direct tumour findings remain too substantial for GREEN.[2,3]

Who may want to limit or avoid E501(ii)

People with kidney disease, high blood potassium, or medicines that raise potassium should avoid unnecessary high intake, especially from supplements or potassium salt substitutes.

Common uses and where E501(ii) appears

E501(ii) is used as a raising agent, acidity regulator, buffer, and potassium source in baked foods, cocoa products, beverages, and other processed foods.

E501(ii) source or origin

It is a synthetic mineral potassium salt commonly made from potassium carbonate or potassium hydroxide and carbon dioxide.

Intake note for E501(ii)

JECFA lists INS 501(ii) with an ADI (Acceptable Daily Intake) of “not limited” within the hydrogen-carbonates group. This does not mean unlimited intake is safe.

Is E501(ii) banned anywhere?

E501(ii) is authorized in the European Union and is GRAS (Generally Recognized as Safe) for direct human food use in the United States under good manufacturing practice. Canada and Australia/New Zealand also permit potassium bicarbonate in food uses.

Safety grading ORANGE – SOME CONCERNS

The key rat studies used unusually high dietary concentrations, but repeated additive-specific bladder lesions and tumours after prolonged exposure create a credible concern.

Study basis or key toxicological reasoning for E501(ii)

Wistar rats received diets containing 2% or 4% potassium bicarbonate for 4 weeks, 13 weeks, 18 months, or 30 months.[1] At 18 months, simple bladder hyperplasia and oncocytic kidney tubules increased at both concentrations, adrenal hypertrophy increased at 4%, and papillary or nodular bladder hyperplasia was statistically significant at 2% but not 4%.[1] In the 30-month study, both concentrations increased preneoplastic bladder lesions. The 4% groups developed bladder papillomas in 2 males and 6 females and carcinomas in 1 male and 3 females.[1] A separate 4-to-130-week program found increased urinary pH, potassium, and volume and concluded that prolonged potassium bicarbonate exposure could induce bladder cancer in rats without a prior initiator.[2] Earlier experiments found that 5% potassium bicarbonate caused bladder epithelial hyperplasia and that dietary acidification prevented the response, supporting urinary alkalinization as an important mechanism.[3] A peer-reviewed review reported a negative Ames test but no comprehensive modern E501(ii) genotoxicity dataset or dedicated reproductive or developmental study.[4] Two randomized human trials lasting about three months provide short-term tolerability data, not long-term bladder-cancer evidence.[5,6] No no-effect concentration was demonstrated in the chronic 2% and 4% rat design because bladder changes were already present at 2%.[1]

Side effects of E501(ii) – Potassium hydrogen carbonate food additive

Bladder effects at extreme intake: Long-term 2% and 4% rat diets caused urothelial hyperplasia, with papillomas and carcinomas after prolonged 4% exposure.[1,2]
Kidney and adrenal findings: High-dose rat studies also reported oncocytic kidney tubules and adrenal hypertrophy.[1,4]
High blood potassium: In a three-month human trial, confirmed hyperkalemia led seven participants to stop study pills: five in the high-dose group, one in the low-dose group, and one receiving placebo.[6]
Digestive intolerance: Five participants in that trial stopped study pills because of gastrointestinal complaints.[6]

Should You Avoid E501(ii) – Potassium hydrogen carbonate food additive?

Most healthy consumers do not need complete avoidance, because normal food exposure is far below the rat study concentrations. Human trials studied substantial potassium bicarbonate supplementation for about three months, but focused on bone, mineral, and tolerability outcomes rather than cancer.[5,6] People with kidney disease, impaired potassium excretion, or potassium-raising medicines should be especially cautious with supplements or other concentrated sources.

Common uses of E501(ii) – Potassium hydrogen carbonate food additive

Baking powders and baked foods: It releases carbon dioxide in leavening systems and helps dough or batter rise.
Reduced-sodium formulations: It can replace part of the sodium bicarbonate used in selected foods.
Cocoa and chocolate products: It may help control acidity and processing conditions.
Confectionery: It can act as a buffer or acidity regulator.
Beverages and powdered mixes: It can provide buffering and pH control.
Other processed foods: It may be used as a formulation aid, processing aid, or potassium source where permitted.

Common names and synonyms of E501(ii) – Potassium hydrogen carbonate food additive

Potassium hydrogen carbonate
Potassium bicarbonate
Potassium acid carbonate
Bicarbonate of potash
KHCO3
INS 501(ii)

What is E501(ii) – Potassium hydrogen carbonate food additive?

E501(ii) is the potassium salt of carbonic acid with the chemical formula KHCO3. It is a white crystalline powder or granule that dissolves readily in water. In foods it functions mainly as a raising agent and acidity regulator. When it reacts with an acid or is heated under suitable conditions, it can release carbon dioxide, which makes it useful in leavening systems.

Commercial potassium hydrogen carbonate is usually made by treating potassium carbonate or potassium hydroxide with carbon dioxide. It supplies potassium rather than sodium, so it can be useful in reduced-sodium formulations. After ingestion it dissociates into potassium and bicarbonate-related ions rather than remaining as an intact complex molecule.[4] The safety question is therefore strongly exposure-dependent. Normal additive use is not comparable with feeding rats diets containing 20 or 40 grams of potassium bicarbonate per kilogram of feed for much of their lifespan. Even so, because those experiments repeatedly produced bladder pathology and eventually tumours, the finding remains relevant enough to justify an ORANGE rather than GREEN grade.

Where is E501(ii) – Potassium hydrogen carbonate food additive allowed (EU vs US)?

E501(ii) is currently authorized in the European Union within E501 potassium carbonates and is permitted across applicable food categories under specified conditions. In the United States, potassium bicarbonate is affirmed as GRAS for direct human food use under current good manufacturing practice as a formulation aid, nutrient supplement, pH-control agent, and processing aid.

E501(ii) – Potassium hydrogen carbonate