What is E634?

Complete guide to understanding E634 (Calcium 5′-Ribonucleotides) in your food

The Quick Answer

E634 is calcium 5′-ribonucleotides, a flavor enhancer made from ribonucleotides (building blocks of RNA) bonded with calcium.

It’s a mixture of calcium salts of guanylic acid (GMP) and inosinic acid (IMP), compounds that naturally occur in living organisms.

It’s used in food to enhance flavor depth and savory taste, particularly in low-sodium products where traditional salt reduction would leave food tasting flat.

What Exactly Is It?

E634 is a mixture of calcium salts of ribonucleotides—specifically guanylic acid (GMP) and inosinic acid (IMP).

Ribonucleotides are nucleotides, the building blocks of RNA (ribonucleic acid). These compounds occur naturally in all living cells—they’re part of the genetic machinery that controls life processes.

When you eat foods like meat, fish, sardines, yeast extract, or mushrooms, you consume natural guanylates and inosinates. E634 is simply a concentrated, purified form made for food manufacturing.

How it works in the mouth:

E634 doesn’t create umami taste on its own (that’s glutamate’s job), but it dramatically amplifies umami perception when combined with glutamate. This synergistic effect means:

• Inosinate + glutamate = vastly enhanced savory flavor perception
• The combination is far more powerful than either compound alone
• Food manufacturers can use less salt while maintaining flavor intensity

Physical form: White to off-white crystalline powder, water-soluble, makes up approximately 0.02-0.2% of low-sodium products.

Where You’ll Find It

E634 appears primarily in low-sodium and reduced-salt products:

• Low-sodium soups and broths
• Reduced-salt sauces and gravies
• Low-salt processed meats and deli products
• Salt-reduced snacks and chips
• Low-sodium instant noodles
• Dietary products for people with salt restrictions
• Some prepared meals and convenience foods
• Certain meat-based products and cured meats
• Some beverages and flavored drink mixes
• Vegetable-based products emphasizing “natural” flavor

E634 is less common than E635 (disodium 5′-ribonucleotides), appearing primarily in products specifically formulated for low-salt diets rather than mainstream processed foods.

Why Do Food Companies Use It?

E634’s primary function is compensating for flavor loss when sodium is reduced.

Food manufacturers face a critical challenge: salt naturally enhances flavor, but many consumers and healthcare professionals want reduced-sodium products. E634 solves this problem:

• Salt reduction enabler: Allows manufacturers to reduce sodium content while maintaining perceived flavor intensity
• Synergistic amplification: When combined with MSG or glutamates, creates powerful umami perception
• Flavor compensation: Makes low-salt food taste flavorful instead of flat and boring
• Health marketing: Enables “low-sodium” and “reduced-salt” claims on labels
• Consumer acceptance: Makes dietary-restricted products more palatable and acceptable
• Cost efficiency: Allows using less of expensive meat extracts or flavorings
• Taste without calories: Enhances flavor without adding significant calories or sugar
• Clean-label appeal: Often perceived as more “natural” than synthetic flavor enhancers because it comes from RNA

This function is particularly important for consumers who need to restrict sodium due to hypertension, heart disease, or kidney conditions. Without E634, low-salt products would be nearly unpalatable.

Is It Safe?

E634 is approved in the EU and most countries, though notably absent from some regulatory systems.

Approval status:

• Approved: European Union (E634), Japan, South Korea, many other countries
• Banned: Australia and New Zealand explicitly prohibit it
• FDA status: Not approved for use in the United States (not listed as GRAS)

Safety profile:

• EFSA has evaluated E634 and found no safety concerns at reported use levels
• No formal Acceptable Daily Intake (ADI) has been established, though approval suggests safe levels
• No documented acute toxicity at normal consumption levels
• The body metabolizes ribonucleotides as it does natural nucleotides from food
• No evidence of carcinogenicity or reproductive toxicity
• Decades of use without documented widespread adverse effects

Critical consideration—purine metabolism:

Like E635 and all ribonucleotide-based flavor enhancers, E634 contains purines that the body metabolizes to uric acid. This creates specific concerns:

Natural vs Synthetic Version

E634 is synthesized, though derived from natural compounds:

Starting materials: Ribonucleotides naturally occur in all living cells—meat, fish, yeast, mushrooms. These can be extracted from natural sources (sardines, yeast extract, meat extract) or synthesized in the laboratory.

Modern production: Most E634 is produced through bacterial fermentation (particularly Bacillus subtilis) using simple sugars as feedstock, or through chemical synthesis.

Perceived “naturalness”: Many consumers view ribonucleotides as more “natural” than synthetic flavor enhancers because they’re based on compounds naturally found in RNA. However, this is a perception rather than a regulatory classification—E634 is synthesized, not simply extracted.

Chemically identical: Regardless of production method, E634 is the same compound. Your body metabolizes it identically.

Natural Alternatives

Want to avoid E634 or manage purine intake?

Some alternatives include:

• Monosodium glutamate (MSG, E621) – More potent umami flavor but also contains amino acids
• Disodium inosinate (E631) – Similar to E634 but with sodium instead of calcium
• Disodium guanylate (E627) – Similar function; also purine-based
• Natural meat extracts – More expensive; contain same purines but in whole-food form
• Yeast extracts – Contains natural glutamates and nucleotides
• Seaweed extracts – Natural umami from kelp or nori
• Mushroom extracts – Natural umami and glutamates
• Tomato extracts – Natural glutamates without high purines
• Simply use less salt – Accept less salty taste; develop palate adjustment

For people with gout or hyperuricemia, reducing overall purine intake (including E634) is often recommended—alternatives should also be checked for purine content.

The Bottom Line

E634 (calcium 5′-ribonucleotides) is a flavor enhancer particularly valuable in low-sodium products.

It’s approved in the EU and many countries, but notably absent from the US market and explicitly banned in Australia and New Zealand.

E634 works by amplifying umami perception, allowing food manufacturers to reduce sodium while maintaining flavor intensity—a critical function for consumers requiring low-salt diets for health reasons.

The key health consideration is that E634 contains purines that metabolize to uric acid. While approved as safe for the general population, it may be inappropriate for people with gout, hyperuricemia, chronic kidney disease, or those managing uric acid levels.

If you have these conditions, consult your healthcare provider before regularly consuming low-sodium products containing E634. For healthy individuals without purine metabolism concerns, E634 at approved levels is considered safe by regulatory bodies.