E-numbers / Thickeners & emulsifiers / E425
also: Glucomannan · Konjac gum (E425i) · Konjac glucomannan (E425ii) · Konjac flour
A plant-based thickener from the konjac root. Used in noodles, low-calorie gels and some dairy alternatives. Banned in mini jelly cups due to choking deaths.
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Konjac gel is very firm and does not dissolve quickly in the mouth.
29
of the 43,325 UK supermarket foods we checked declare E425 in their ingredients
That is under 0.1%, 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. Konjac gel is very firm and does not dissolve quickly in the mouth. In small, rigid confectionery cups it has caused children to choke fatally. It is now banned from jelly mini-cups in the UK and EU. People with swallowing difficulties should be cautious with any konjac product.
Konjac (E425) is extracted from the corm of Amorphophallus konjac, a plant native to East and Southeast Asia. It exists in two permitted forms: konjac gum (E425i), a dried powder, and konjac glucomannan (E425ii), the purified polysaccharide. Konjac glucomannan is an exceptionally water-absorbent fibre, capable of absorbing many times its own weight in water to form a dense, firm gel.
When mixed with water, konjac glucomannan swells and forms a very viscous, cohesive gel. This makes it effective as a thickener, gelling agent and stabiliser. In the gut, the gel slows digestion and reduces the absorption of glucose and cholesterol. As a food additive, it gives low-calorie foods bulk and a satisfying texture with minimal calories.
Konjac noodles and rice (shirataki products), low-calorie gels and desserts, vegan and vegetarian meat alternatives, some reduced-fat dairy alternatives, and certain sauces and dressings. On a label it appears as Konjac, Konjac Gum, Konjac Glucomannan, or E425.
Unlike gelatine, konjac gel is very firm, smooth and slow to dissolve in the mouth. When set inside small, rigid mini-cup containers it can slide to the back of the throat and create a physical airway blockage. Multiple fatal choking incidents, primarily involving children, were reported in Europe and elsewhere in the late 1990s and early 2000s. These led to an EU emergency suspension in 2002 and a permanent ban in jelly mini-cup confectionery from 2004.
The European Commission issued an emergency suspension in 2002 on konjac-containing jelly mini-cups after several choking deaths, citing the product's firmness, slipperiness and failure to dissolve. A permanent ban on E425 in jelly mini-cups followed in 2004.
EFSA's re-evaluation noted historical cases of oesophageal obstruction from konjac taken in tablet form without adequate liquid, which contributed to the rationale for restricting its use in jelly confectionery.
At doses of around 3g per day (used in clinical weight-management and cholesterol trials), konjac glucomannan causes abdominal discomfort, bloating, diarrhoea or constipation in some people. These effects are well above typical food-additive exposure levels but are relevant for people who take konjac supplements or eat large portions of konjac noodles daily.
In 90-day animal studies, a no-observed-effect level of 1,250mg/kg body weight per day was established for konjac gum. No genotoxicity was found.
At 3,000mg daily over 12 weeks, several human subjects experienced abdominal discomfort including diarrhoea or constipation.
EFSA's 2017 re-evaluation found no chronic toxicity or carcinogenicity studies and no reproductive or developmental toxicity studies for either konjac gum or konjac glucomannan. The Panel concluded the current additive use levels appeared acceptable, but noted the toxicological database was limited and that only three out of 67 authorised food categories had submitted usage-level data.
No chronic toxicity, carcinogenicity, reproductive toxicity or developmental toxicity studies were available for konjac gum or konjac glucomannan at the time of re-evaluation.
Children and anyone with swallowing difficulties should avoid products where konjac forms a firm, rigid gel, particularly any jelly cup-style products (now banned in the UK if small). People taking medications that slow gut transit should be aware that konjac fibre can reduce absorption of some drugs. Supplements and tablets must be taken with a full glass of water. Look for Konjac, Konjac Gum, Konjac Glucomannan, or E425 on the label.
Konjac's story is unusual: it is a well-established ingredient in East Asian cuisine with centuries of use, permitted across a wide range of foods in the UK and EU, yet it also has a specific, serious track record of causing choking deaths when set inside small, rigid jelly cups. That use is now permanently banned. In the food categories where it is still permitted, such as noodles, sauces and dairy alternatives, exposure levels from the additive are low. The bigger safety question for regular konjac consumers is the cumulative fibre dose from food, not the additive classification. EFSA's 2017 review left notable gaps unfilled, including no chronic or reproductive toxicity data. That does not mean harm has been found; it means the long-term picture is not fully drawn.
Not outright. Konjac (E425) is banned specifically in jelly mini-cup confectionery measuring 45mm or less in height or width, because that format caused fatal choking incidents. The ban covers England under SI 2009/3230 and mirrors EU law. Konjac remains permitted in a wide range of other foods including noodles, dairy alternatives, sauces and gels above the prohibited size.
Yes. Multiple choking fatalities, including deaths of children, were reported in Europe in the late 1990s and early 2000s linked to konjac jelly mini-cups. The gel sets very firmly, does not dissolve quickly and can block the airway. The EU issued an emergency suspension in 2002 and a permanent ban on that product format in 2004. No comparable incidents are reported from konjac noodles or other food uses.
Konjac noodles and shirataki rice, some low-calorie jelly desserts, vegan and vegetarian meat alternatives, reduced-fat dairy-style products, and certain sauces and dressings. It appears on labels as Konjac, Konjac Gum, Konjac Glucomannan, or E425.
Yes. Konjac is derived entirely from the konjac plant root and contains no animal products. It is widely used in vegan and vegetarian food products as an alternative to gelatine.
Last reviewed: 20 June 2026
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