What is E635?

Complete guide to understanding E635 (Disodium 5′-Ribonucleotides) in your food

The Quick Answer

E635 is a flavor enhancer made from a mixture of disodium inosinate and disodium guanylate (also called “I+G”).

It’s used in food to intensify savory taste, particularly the “umami” flavor that makes food taste meatier and more satisfying.

It’s particularly potent when combined with MSG, making it four times more flavor-enhancing than MSG alone.

What Exactly Is It?

E635 is a mixture of two nucleotide salts in equal proportions (50/50):

• Disodium inosinate (IMP) – Derived from inosinic acid
• Disodium guanylate (GMP) – Derived from guanylic acid

Nucleotides are the building blocks of RNA (ribonucleic acid), found naturally in all living cells. In food science, these specific nucleotides are renowned for creating synergistic umami flavor.

The name “5′-ribonucleotides” refers to the chemical structure—the nucleotide molecule connected at the 5′ position of the ribose sugar.

E635 typically appears as white, odorless crystalline powder that is highly soluble in water.

Where You’ll Find It

E635 is widely used in savory processed foods:

• Instant noodles and cup soups
• Snack foods, chips, and crackers
• Seasoning blends, bouillon cubes, and stock powders
• Flavored noodles and rice products
• Sauces, gravies, and condiments
• Ready meals and convenience foods
• Some processed meat and fish products
• Vegetable seasonings
• Bisto gravies and similar products

It’s particularly common in Asian food products and instant noodle brands.

Many consumers don’t notice E635 because it’s used at relatively low concentrations, but it significantly influences perceived flavor intensity.

Why Do Food Companies Use It?

E635’s primary function is umami flavor enhancement—creating deep, savory, meaty taste sensations.

E635 provides manufacturers with significant advantages:

• Synergistic power: When combined with MSG, it becomes four times more potent than MSG alone
• Umami intensity: Binds to the same taste receptors as glutamate, creating powerful savory perception
• Salt reduction: Allows manufacturers to reduce sodium content while maintaining flavor
• Cost efficiency: Enables “meaty” taste without expensive meat extract or whole ingredients
• Flavor consistency: Creates uniform taste across batches of instant foods
• Consumer appeal: Makes inexpensive processed foods taste richer and more satisfying
• MSG-free claims: Can be used as a replacement for MSG in “MSG-free” products while delivering similar flavor effects

The potency of E635 means manufacturers can use small amounts (typically 0.01%-1% depending on the food) to achieve significant flavor enhancement.

Is It Safe?

E635 is approved by major regulatory authorities and is considered safe at approved use levels for the general population.

The FDA and EFSA have both authorized its use, and it appears on approved additives lists globally.

General safety for healthy people:

• No adverse effects known to occur in healthy people at normal dietary intake levels
• The Joint FAO/WHO Expert Committee on Food Additives set an ADI of “not specified” in 1974 (meaning no safety concern was identified)
• Decades of use in Asian cuisines without documented widespread health incidents
• Maximum permitted levels are carefully regulated (ranging from 0.01% to 1.00% depending on food type)
• The body metabolizes E635 as it does natural nucleotides from food

Important considerations for vulnerable groups:

E635 is metabolized in the body to purines, which are then converted to uric acid. This creates concerns for specific populations:

• Gout sufferers: Higher purine intake increases serum uric acid levels, worsening gout symptoms and increasing attack risk
• Hyperuricemia: People with elevated uric acid levels should limit purine consumption
• Chronic kidney disease: Impaired kidney function makes purine metabolism more problematic
• Asthma: Some asthmatic individuals report sensitivity to guanylates and inosinates

For these groups, it’s reasonable to limit foods containing E635, particularly when consuming multiple processed savory products daily.

Natural vs Synthetic Version

E635 can be made from natural or synthetic sources:

Original source: Historically derived from animal tissues (sardines, pig intestines, meat extract), these were the first sources used.

Modern production (plant-based): Today, E635 is predominantly produced through bacterial fermentation using:

• Glucose or molasses as carbon source
• Genetically modified strains of bacteria (Corynebacterium glutamicum or Bacillus subtilis)
• Aerobic fermentation in large bioreactors

This fermentation process is more sustainable, cost-effective, and allows for vegan and vegetarian claims on product labels.

Regardless of source, the final chemical product is identical—your body cannot distinguish between E635 made from fermentation versus that made from meat extract.

Natural Alternatives

Want to avoid E635 or limit purine intake?

Some alternatives include:

• Monosodium glutamate (MSG, E621) – Another umami flavor enhancer (though also purine-related)
• Natural meat extracts – Used in premium seasonings but more expensive
• Yeast extracts and nutritional yeast – Provide umami without isolated nucleotides
• Aged cheeses and fermented foods – Natural umami from glutamates
• Whole herbs and spices – Traditional flavoring without synthetic additives
• Mushrooms and tomatoes – Natural foods high in glutamates

Premium and specialty products more commonly use these alternatives, though they typically cost significantly more than E635.

The Bottom Line

E635 (disodium 5′-ribonucleotides) is a potent flavor enhancer used to create savory, umami taste in processed foods.

It’s approved for use by the FDA, EFSA, and food authorities worldwide.

For healthy people without metabolic disorders, E635 at approved levels is considered safe.

However, for people with gout, hyperuricemia, chronic kidney disease, or those advised to limit purines, E635-containing foods should be consumed carefully and monitored.

The additive is particularly common in instant noodles and savory snacks—products that are easy to overconsume, which can increase cumulative purine intake.

Being aware of E635 in your diet helps you make informed choices, especially if you’re managing uric acid levels or have related metabolic conditions.