E-numbers / Flavour enhancers / E635
also: Disodium ribonucleotides · Sodium 5'-ribonucleotides · I+G · IMP+GMP blend
A mixture of two purine nucleotides used to amplify savoury flavour, often found in crisps, instant noodles, and flavour sachets.
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Salt, Flavour Enhancers: E621 and E635, Garlic, Onion, Flavours, Palm Vegetable Fat, Wheat Starch, Colour: Turmeric, Riboflavin-5-Phosphate
Purines in E635 are broken down into uric acid in the body.
86
of the 43,325 UK supermarket foods we checked declare E635 in their ingredients
That is 0.2%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Why it’s worth knowing. Purines in E635 are broken down into uric acid in the body. Regular intake can worsen gout, raise uric acid levels, and may aggravate uric acid kidney stones in people prone to them.
E635 is a blend of two sodium salts of nucleotides: disodium inosinate (E631, derived from inosine 5'-monophosphate) and disodium guanylate (E627, derived from guanosine 5'-monophosphate). Together they are often labelled 'I+G' in food manufacturing. Both components are purine nucleotides, naturally present in small amounts in meat, fish, and some fungi. The commercial form is typically produced by fermentation of yeast or by extraction from fish and meat.
E635 enhances the perception of umami, the savoury fifth taste. It works synergistically with glutamates: a blend of 98% monosodium glutamate and 2% E635 delivers roughly four times the flavour-enhancing effect of MSG alone. This synergy means manufacturers can use far lower total levels to achieve the same taste intensity. The nucleotides bind to taste receptors and potentiate the glutamate signal, prolonging and deepening the savoury sensation.
Most common in crisps and savoury snacks, instant noodles and ramen sachets, powdered seasoning mixes, packet soups, savoury biscuits and crackers, processed meats, fast food sauces, and ready meals. On a UK ingredient label it appears as 'disodium 5'-ribonucleotides' or 'flavour enhancer (E635)'.
Both inosinate and guanylate are purine nucleotides. The body metabolises purines from food into uric acid. In most people this is handled without consequence, but in those with gout, hyperuricaemia, or uric acid kidney stones, extra dietary purines can raise uric acid further and trigger or worsen symptoms. The purine load from E635 at typical food additive levels is modest compared to, say, a serving of offal, but it is additive to the overall dietary purine load.
Dietary purines, including nucleotides such as inosinate and guanylate, are catabolised to uric acid in humans. Elevated uric acid is the direct driver of gout attacks and uric acid nephrolithiasis.
JECFA re-evaluated disodium 5'-ribonucleotides in 1993 and assigned an 'ADI Not Specified' designation, meaning no numerical acceptable daily intake was set because toxicological studies showed no adverse effects at typical intake levels. The evaluation noted the purine metabolism consideration for gout-prone individuals.
Commercially, E635 is produced either by fermentation of yeast and bacterial cultures or by hydrolysis of sardines, meat, or poultry. The fermentation route is not necessarily vegan because the starter substrate may be animal-based. Unless a product is certified vegan or the manufacturer specifies a plant-based production route, E635 must be treated as potentially animal-derived, making it unsuitable for vegans and many vegetarians.
Disodium inosinate (the IMP component of E635) is most commonly produced by the hydrolysis of dried sardines or by bacterial fermentation, and disodium guanylate (the GMP component) is typically derived from tapioca starch fermentation or dried fish. The production route varies by manufacturer.
There are anecdotal reports of reactions such as skin flushing, rashes, and headaches attributed to E635 and related nucleotide enhancers, sometimes described as 'Chinese restaurant syndrome' alongside MSG. Controlled clinical studies specifically isolating E635 are limited. Current regulatory opinion does not recognise a confirmed intolerance mechanism at permitted levels.
Case reports and consumer complaints have associated nucleotide flavour enhancers (E627, E631, E635) with skin reactions including urticaria-like rashes. Causality has not been established in controlled clinical trials.
People with gout, hyperuricaemia, or uric acid kidney stones should limit foods containing E635 because it adds to the overall dietary purine load. Vegans and many vegetarians should avoid it unless the product is certified vegan, as the additive is often derived from fish or meat. Look for 'disodium 5'-ribonucleotides' or 'flavour enhancer (E635)' in the ingredients list.
E635 is one of the most widely used flavour enhancers in processed snack foods, and it has been in commercial use for decades. The regulatory picture is straightforward: no numerical daily limit, no flagged toxicological hazard at food doses. The genuine issue is metabolic: purines from this additive do end up as uric acid in the body, and for the sizable minority of people who have gout or are on a low-purine diet, that matters. The animal-origin question is also real and often overlooked: without manufacturer disclosure, you cannot assume it is plant-derived. There is no established intolerance mechanism for E635 at the levels used in food, but self-reported reactions are common enough that some allergy and intolerance communities flag it. Its usual home is the processed snack aisle, so it is a fair marker of how far a product has been built rather than cooked. Our UPF checker names that on a scanned pack.
No. E635 is approved for use in the UK under the FSA approved-additives list and assimilated EU Regulation 1333/2008. It is permitted in a range of food categories including snack foods, sauces, soups, and ready meals.
It can contribute to a gout flare in susceptible people. E635 is composed of purine nucleotides that the body converts to uric acid. For most people the amount from a packet of crisps is small compared to the total dietary purine load, but those already managing gout or high uric acid are advised to limit purine-containing additives including E635, E631, and E627.
E635 is most commonly found in flavoured crisps and snack foods, instant noodles and ramen flavour sachets, packet soups and stock cubes, powdered seasoning mixes, sauces, processed meats, and some ready meals. Check the label for 'disodium 5'-ribonucleotides' or 'flavour enhancer (E635)'.
Not reliably. The disodium inosinate component (E631) is commonly produced from dried sardines or other fish, and sometimes from poultry. The disodium guanylate component (E627) is more often fermentation-derived, but the fermentation substrate can be animal-based. Unless a product is certified vegan, E635 should be treated as potentially animal-derived.
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