What is E508?
Complete guide to understanding E508 (Potassium Chloride) in your food
The Quick Answer
E508 is potassium chloride (KCl), a mineral salt composed of potassium and chlorine, used as a sodium replacement in low-sodium and salt-free products—functioning as a salt substitute that delivers salty taste while reducing sodium intake for cardiovascular health management.
It’s an inorganic salt that occurs naturally as the mineral sylvite (or in combination with sodium chloride as sylvinite), used in salt substitutes, low-sodium foods, mineral waters, and various food products where sodium reduction is desired while maintaining salt-like flavor and mineral content.
E508 potassium chloride is widely used in low-sodium and salt-free food products, functioning as a sodium-reducing ingredient with regulatory approval across multiple jurisdictions, though with documented risks for certain populations (those with kidney disease, diabetes, those on specific medications) who must restrict potassium intake.
📌 Quick Facts
- Category: Mineral Salt, Sodium Substitute, Electrolyte Replenisher
- Source: Mined from natural deposits (sylvite mineral) or synthesized chemically through potassium hydroxide and hydrochloric acid reaction
- Found in: Low-sodium salts, salt substitutes, low-sodium processed foods, mineral waters, cheese production, brewer’s yeast
- Safety: EFSA approved; FDA GRAS approved; JECFA approved; ADI not established (EFSA 2019) due to insufficient data
- Natural or Synthetic: Occurs naturally as mineral sylvite; also synthetically produced
- Vegan/Vegetarian: Yes
- Key Advantage: Natural mineral origin; effective sodium replacement; provides potassium nutrition; no known adverse effects at food-use levels for healthy individuals
- Key Concern: Potassium toxicity risk for vulnerable populations (kidney disease, diabetes, ACE inhibitor/ARB medications); bitter/metallic aftertaste; warning labels recommended for at-risk groups
- Chemical Formula: KCl; potassium cation (K⁺) and chloride anion (Cl⁻)
The Critical Context—Effective Sodium Substitute With Cardiovascular Benefit But Toxicity Risks for Vulnerable Groups
E508 potassium chloride is a mineral salt approved as sodium substitute in low-sodium foods and salt replacements, with regulatory approval reflecting cardiovascular benefits of sodium reduction (hypertension management, heart disease prevention), yet carrying documented potassium toxicity risks (hyperkalemia) for vulnerable populations including those with kidney disease, diabetes, and those taking ACE inhibitors or ARB medications, requiring medical guidance for at-risk individuals considering potassium salt substitutes.
What Exactly Is It?
E508 is potassium chloride (potassium salt, KCl), an inorganic mineral salt with molecular formula KCl and molecular weight of 74.55 g/mol, composed of potassium cation (K⁺) and chloride anion (Cl⁻).
Potassium chloride occurs naturally as the mineral sylvite (from the German “sylvin,” meaning salt), found in ancient salt deposits and salt lakes. It also occurs in combination with sodium chloride as sylvinite. Large deposits are mined in North America, Europe, Asia, and other regions. The mineral can also be synthesized chemically by reacting potassium hydroxide (KOH) with hydrochloric acid (HCl).
Physically, E508 appears as white or colorless cubic crystals with no odor and high water solubility (approximately 110 g/100 mL at 20°C). The crystals are stable in air and closely resemble common table salt (sodium chloride) in appearance.
Chemically, E508 functions as an electrolyte and mineral supplement: the potassium ion (K⁺) is essential for muscle function, nerve signaling, and cardiac rhythm; the chloride ion (Cl⁻) is essential for acid-base balance and osmotic regulation. When ingested, E508 ionizes completely into K⁺ and Cl⁻ ions, which are absorbed and distributed throughout the body.
Where You’ll Find It
E508 potassium chloride appears in various food categories where sodium reduction is desired:
• Low-sodium salt substitutes and salt replacements (primary application)
• Low-sodium processed foods (soups, condiments, processed meats)
• Reduced-sodium baked goods
• Low-sodium mineral waters and beverages
• Cheese production (helps with texture and protein breakdown)
• Brewer’s yeast production
• Mineral supplementation in foods
• Fruit and vegetable preservation (improves peel firmness)
• Condensed milk
• Some pharmaceutical formulations
• Water treatment and defrosting products (secondary food-related application)
E508 is particularly prevalent in products marketed for cardiovascular health, hypertension management, or “low-sodium” positioning. Consumers managing blood pressure or heart disease often intentionally consume potassium chloride-containing salt substitutes.
Why Do Food Companies Use It?
E508 potassium chloride performs multiple critical commercial functions with specific health and marketing advantages:
Sodium reduction with flavor maintenance and potassium addition: E508 potassium chloride provides salty taste (though with slight bitter or metallic note compared to sodium chloride) while eliminating the sodium associated with cardiovascular disease risk (hypertension, heart attack, stroke). For health-conscious consumers, the trade-off of slightly altered taste for sodium elimination is compelling. Additionally, E508 provides dietary potassium, which has cardiovascular protective properties (helps regulate blood pressure). At 0.5-5% concentrations (depending on food type), potassium chloride achieves effective sodium reduction while maintaining product palatability.
Why potassium chloride over other sodium replacements: E508 is selected over other sodium substitutes (artificial sweeteners for umami replacement, etc.) because it provides both flavor (salty taste) and nutritional benefit (potassium provision). The mineral origin and GRAS/approved status reflect regulatory confidence. Marketing advantage: “naturally sourced mineral salt” positioning appeals to consumers.
Is It Safe?
E508’s safety status is APPROVED for food use by EFSA, FDA, and JECFA, with established safe use for healthy individuals, though CRITICAL RISKS exist for vulnerable populations (kidney disease, diabetes, certain medications) requiring medical guidance before use.
Regulatory Status—Approved with Population Restrictions:
• EFSA (Europe): Approved (2019 re-evaluation); ADI not established due to insufficient data; concluded safe at food-use levels for healthy individuals
• FDA (USA): GRAS (Generally Recognized As Safe) for food use; also approved as pharmaceutical ingredient
• JECFA (WHO/FAO): Approved as food additive
• CRITICAL RESTRICTION: Not recommended for individuals with kidney disease, diabetes, or those taking ACE inhibitors/ARBs without medical consultation
⚠️ CRITICAL SAFETY CONCERN—POTASSIUM TOXICITY (HYPERKALEMIA) IN VULNERABLE POPULATIONS: E508 potassium chloride has documented serious health risks for specific population groups:
• Hyperkalemia risk: For healthy individuals with normal kidney function, dietary potassium is regulated through renal excretion; excess potassium is readily excreted. However, for individuals with kidney disease or impaired kidney function, potassium accumulation can occur, leading to hyperkalemia (elevated serum potassium)—a serious condition causing cardiac arrhythmias, muscle weakness, and potentially life-threatening outcomes
• Diabetes risk: Diabetes (particularly Type 2) is associated with impaired potassium regulation and increased hyperkalemia risk; diabetics must restrict potassium intake
• Medication interactions: ACE inhibitors (ACE-I) and Angiotensin II Receptor Blockers (ARBs)—common cardiovascular medications—reduce urinary potassium excretion, increasing hyperkalemia risk in individuals using these medications
• Additive medications: Potassium-sparing diuretics (spironolactone), NSAIDs, and other medications increase hyperkalemia risk
• Case reports: UK Food Standards Agency noted case reports of potassium poisoning from salt substitutes in individuals with underlying risk factors
• Elderly population: Age-associated decline in kidney function increases hyperkalemia risk in elderly individuals
• Symptom delayed: Hyperkalemia may be asymptomatic until severe; individuals cannot self-diagnose potassium toxicity without serum potassium testing
• Regulatory response: UK Food Standards Agency recommended that potassium-containing salt substitutes be labeled with warnings: “Not for persons on potassium-restricted diets” and similar cautions
• Healthy individuals safe: EFSA and FDA confirm that healthy individuals with normal kidney function can safely consume food-use levels of potassium chloride; the risk is specific to vulnerable populations
Documented safety findings:
• No genotoxicity: No evidence of genotoxic potential at food-use levels
• No carcinogenicity: No evidence of carcinogenic potential
• Safe for healthy individuals: EFSA concluded potassium chloride is safe at food-use levels for individuals with normal kidney function
• Taste issue: Documented side effect is bitter or metallic aftertaste (not a safety concern, but palatability issue limiting acceptance)
• Hyperkalemia in at-risk groups: Well-documented risk for kidney disease, diabetes, elderly, those on certain medications
• Absorption complete: Potassium chloride is completely absorbed and ionized in the GI tract; bioavailability is high
• No bioaccumulation: Potassium does not accumulate in tissues; excess is excreted through kidneys (assuming normal kidney function)
• Adequate Intake (AI): EFSA establishes recommended potassium intake of 3,500 mg/day for adults; foods with E508 contribute to this requirement while potentially reducing excessive sodium
Natural vs Synthetic Version
E508 potassium chloride exists in both natural mineral and synthetically produced forms, chemically identical:
Potassium chloride occurs naturally as the mineral sylvite, mined from ancient salt deposits and geological formations. It can also be synthesized chemically through reaction of potassium hydroxide with hydrochloric acid. Both forms are chemically identical (KCl) and produce the same physiological effects. Food-grade E508 can be sourced from either mined mineral deposits or chemical synthesis, with equivalent safety profiles and effectiveness as salt substitute.
Sodium Reduction and Cardiovascular Benefits
The primary value proposition for E508 potassium chloride is sodium reduction—a significant public health goal for hypertension and cardiovascular disease prevention:
Dietary sodium is a major risk factor for hypertension, affecting approximately 1 billion individuals globally. Sodium reduction strategies (including potassium chloride salt substitutes) are recommended by major health organizations (WHO, American Heart Association, etc.) as evidence-based interventions for blood pressure lowering. Studies document that potassium chloride-based salt substitutes reduce systolic blood pressure by approximately 4-8 mmHg and diastolic by 2-4 mmHg—modest but clinically significant reductions particularly important in hypertensive individuals. Additionally, the potassium content of E508 provides independent cardiovascular benefit (potassium lowers blood pressure and reduces cardiovascular risk through multiple mechanisms).
This cardiovascular benefit explains the regulatory approval and widespread commercial adoption of E508 salt substitutes—they represent evidence-based intervention for disease prevention in appropriate populations.
Production Method
E508 potassium chloride is produced through two methods: mining from natural mineral deposits and chemical synthesis:
Mining from natural deposits:
1. Potassium chloride-rich mineral deposits (sylvite) are identified and extracted through surface or underground mining
2. Mined material is crushed and processed
3. Impurities (primarily sodium chloride, magnesium salts) are removed through various separation methods (flotation, crystallization)
4. Purified potassium chloride is crystallized and dried
5. Product is ground to desired particle size and standardized for purity
6. Final product is packaged for food use
Chemical synthesis:
1. Potassium hydroxide (KOH) is reacted with hydrochloric acid (HCl)
2. Reaction: KOH + HCl → KCl + H₂O
3. Water is evaporated to concentrate the potassium chloride
4. Potassium chloride crystallizes as white crystals
5. Crystals are filtered, washed, and dried
6. Product is standardized for purity and specifications
Both production methods yield chemically identical potassium chloride suitable for food use.
Comparison with Sodium Chloride (Table Salt) and Other Sodium Substitutes
E508 potassium chloride represents one option in the sodium reduction landscape:
• Sodium chloride (NaCl): Traditional salt; salty taste; high sodium; associated with hypertension and cardiovascular disease
• E508 (Potassium chloride): Salt-like taste with bitter/metallic note; eliminates sodium; provides potassium benefit; hyperkalemia risk for vulnerable groups; most commonly used sodium substitute
• Magnesium chloride (E511): Bitter taste; less commonly used; some potassium sparing; different risk profile
• Calcium chloride (E509): Bitter/metallic taste; some mineral benefit; less commonly used
• Amino acid-based substitutes: Provide umami without sodium; no potassium overload; taste advantage; higher cost
• Non-nutritive sweeteners: Not true salt substitutes; cannot replace sodium in flavor or function
E508 potassium chloride is the MOST COMMONLY USED sodium substitute globally due to balance of effectiveness, cost, and regulatory acceptance.
Clinical Use and Pharmaceutical Context
E508 potassium chloride is approved and extensively used as a pharmaceutical medication in addition to food use:
Potassium chloride is a prescription medication used to treat hypokalemia (low blood potassium) resulting from diuretic use, poor dietary intake, or disease conditions. Pharmaceutical-grade potassium chloride demonstrates safety profile exceeding food-use exposure. However, pharmaceutical use also highlights hyperkalemia risk in at-risk populations—prescribing guidelines for pharmaceutical potassium explicitly warn against use in kidney disease, diabetes, and those on ACE inhibitors/ARBs without careful monitoring.
Taste Profile and Palatability
A documented limitation of E508 potassium chloride is taste—the salt substitute exhibits slightly bitter and metallic aftertaste compared to sodium chloride:
While potassium chloride provides adequate salty taste (acceptable to many consumers), the slightly bitter/metallic note limits acceptance in some applications and consumers. This taste limitation has driven development of alternative sodium substitutes and combination approaches (mixing potassium chloride with other minerals to improve taste). The taste limitation is not a safety concern but a palatability/acceptance issue affecting commercial adoption in premium food applications.
Environmental and Sustainability
E508 potassium chloride from mined deposits represents sustainable resource extraction—potassium is abundant in Earth’s crust and mining ancient salt deposits has minimal environmental impact. Chemical synthesis, while energy-intensive, avoids mining impacts. Overall, potassium chloride as sodium substitute has positive environmental profile compared to continued reliance on high-sodium foods contributing to disease burden.
Consumer Actions Regarding E508
For consumers considering potassium chloride-based salt substitutes:
• Healthy individuals with normal kidney function: E508 is safe and beneficial for sodium reduction and cardiovascular health management
• Those with kidney disease: MUST consult physician before using potassium salt substitutes; hyperkalemia risk is serious
• Diabetics: MUST consult physician; diabetes increases hyperkalemia risk
• Those on ACE inhibitors/ARBs: MUST consult physician; these common heart medications increase potassium retention
• Elderly individuals: Should consult physician; age-related kidney function decline increases hyperkalemia risk
• Those on potassium-sparing medications: MUST consult physician
• Taste preference: Some consumers find bitter/metallic note unacceptable; taste testing recommended before commitment
• Regular blood potassium monitoring: For at-risk individuals considering E508 use, periodic serum potassium testing is essential to monitor for hyperkalemia
The Bottom Line
E508 (potassium chloride) is a mineral salt composed of potassium and chlorine occurring naturally as sylvite mineral or produced through chemical synthesis, approved by EFSA, FDA, and JECFA as sodium substitute in low-sodium foods and salt replacements, functioning as effective cardiovascular intervention through combined sodium reduction and potassium supplementation with documented blood pressure-lowering effects—yet carrying CRITICAL HYPERKALEMIA RISK for vulnerable populations including those with kidney disease, diabetes, those taking ACE inhibitors/ARBs, and elderly individuals, requiring medical guidance before use by at-risk groups despite safety for healthy individuals with normal kidney function.
E508 is an inorganic mineral salt that completely ionizes into potassium (K⁺) and chloride (Cl⁻) ions when dissolved. It occurs naturally as mineral sylvite or is synthetically produced through potassium hydroxide and hydrochloric acid reaction. Both sources are chemically identical and equally safe/effective.
The critical distinction of E508 is the paradox between population-specific benefit and population-specific risk: for healthy individuals with normal kidney function, potassium chloride represents an evidence-based intervention for hypertension and cardiovascular disease prevention—combining sodium elimination with potassium supplementation. Multiple studies document blood pressure reduction and cardiovascular benefit. Regulatory approval reflects this benefit for appropriate populations.
However, for vulnerable populations (kidney disease, diabetes, ACE inhibitor/ARB use, elderly), potassium chloride-based salt substitutes carry serious hyperkalemia risk—dangerously elevated serum potassium causing cardiac arrhythmias, muscle weakness, and potentially fatal outcomes. The UK Food Standards Agency documented case reports of potassium poisoning from salt substitutes in at-risk individuals, prompting recommendations for warning labels on potassium products.
The taste profile (slight bitter/metallic aftertaste) represents a secondary concern—some consumers find E508 acceptable, while others reject it as unpalatable. This limitation has driven development of alternative sodium substitutes combining different minerals or amino acids.
E508’s safety is fundamentally conditional: beneficial for healthy individuals managing cardiovascular health; dangerous for those with kidney/metabolic disease. Unlike most food additives discussed in this guide, E508 requires individualized medical assessment for vulnerable populations before consumption.
For consumers, E508 represents an evidence-based sodium reduction strategy when medical guidance indicates appropriateness. The regulatory approval and widespread commercial adoption reflect cardiovascular benefits for appropriate populations, balanced against well-documented risks for vulnerable groups requiring physician consultation before use.