Niacin
A B vitamin (nicotinic acid) added to flour and fortified foods. Carries an E number but is not authorised as a food additive in the UK or EU.
What is it?
Niacin (vitamin B3) exists in two forms: nicotinic acid and nicotinamide (niacinamide). Both are water-soluble B vitamins essential for energy metabolism. Nicotinic acid is the form that carries the E375 designation. It occurs naturally in meat, fish, nuts, and wholegrains, and is synthesised from the amino acid tryptophan in the body.
What does it do?
In the body, niacin is a precursor to the coenzymes NAD and NADP, which are central to energy release from carbohydrates, fats, and proteins, and to DNA repair. In food, nicotinic acid is used as a colour stabiliser in cured meats in some countries (it reacts with myoglobin to produce a pink nitric-oxide-myoglobin complex), and as a nutrient supplement in fortified flour and cereals. It has mild antioxidant properties.
Where you will see it
Fortified white and wholemeal flour (UK flour fortification regulations require niacin addition), breakfast cereals, bread, some energy drinks, and nutritional supplements. On UK food labels it usually appears as 'niacin', 'nicotinic acid', or 'nicotinamide', not as E375.
What the science says
High-dose flushing and skin effects
At doses far above dietary intake, nicotinic acid (but not nicotinamide) causes a flushing reaction: redness, warmth, and itching of the skin, lasting 15 to 60 minutes. This is a pharmacological effect mediated by prostaglandins and occurs at supplemental or therapeutic doses typically above 30 to 50 mg, well above the few milligrams added to food. At intakes achievable from fortified food alone, flushing is not expected.
Nicotinic acid triggers cutaneous flushing via GPR109A receptor activation and prostaglandin D2 release; threshold for this effect in most adults is around 30 to 50 mg as a single bolus dose.
Liver effects at very high supplemental doses
Sustained high-dose nicotinic acid (typically 1,000 to 3,000 mg per day in therapeutic contexts) has been associated with liver toxicity, including raised liver enzymes and, rarely, hepatitis. These are pharmacological effects seen in clinical or supplement settings, not from niacin as added to food. The amounts present in fortified foods are several orders of magnitude lower.
Hepatotoxicity has been reported with extended-release nicotinic acid formulations at doses of 1,000 mg per day and above, with raised transaminases resolving on discontinuation.
SACN concluded that the tolerable upper intake level for niacin from all sources (food and supplements) is 17 mg per day for adults to avoid flushing, while WHO/FAO upper level is 35 mg per day for nicotinic acid specifically.
Colour stabilisation use in meat (not UK-permitted as additive)
Nicotinic acid has been used in some countries to fix the pink colour of fresh meat, acting as a colour stabiliser. This use is not authorised in the UK or EU under food additive law. Its absence from Annex II of EU Regulation 1333/2008 and the UK FSA approved additives list means it cannot legally be added to food as a functional additive in Great Britain or the EU, though it may be added as a nutrient under separate fortification legislation.
E375 does not appear in the UK FSA's approved additives and E numbers list, confirming it is not authorised as a food additive under UK food law.
Where it stands with the regulators
Who should be careful
People taking high-dose nicotinic acid supplements (above 30 to 50 mg) may experience flushing; those on statins or with liver conditions should be cautious at pharmacological doses. At the levels found in fortified foods, this does not apply. Look for 'nicotinic acid', 'niacin', or 'nicotinamide' on the label.
The honest read
E375 is an unusual case: it has an E-number in some reference databases, but it is not listed as an approved food additive in either UK or EU food additive law. The niacin you encounter in fortified bread, flour, and breakfast cereals is added under nutritional legislation, not as a functional additive. The only real-world concern around niacin is dose-dependent and confined to high-strength supplements or therapeutic use, not to the milligram-level amounts in everyday food. The science on its role as an essential vitamin is decades old and well-established; the science on high-dose pharmacological effects in supplements is also well-established, and those doses are not achievable from fortified food.
Related additives
Common questions
Is E375 banned in the UK?
E375 is not listed as a permitted food additive in the UK or EU. It has an E-number designation in some reference sources but does not appear in the UK FSA's approved additives list. Niacin is, however, legally added to food as a nutrient under separate fortification rules, such as the UK Bread and Flour Regulations.
Can niacin in food cause flushing?
The flushing reaction caused by nicotinic acid requires doses typically above 30 to 50 mg taken at once. Fortified foods contain a few milligrams per serving, which is too low to trigger this effect. High-dose niacin supplements are a different matter.
What foods contain E375?
Niacin appears in fortified white flour, bread, breakfast cereals, and some energy drinks. It is labelled as 'niacin', 'nicotinic acid', or 'nicotinamide', rarely as E375. It also occurs naturally in meat, fish, peanuts, and wholegrains.
Is E375 vegan?
Yes. Niacin used in food fortification is synthesised chemically or via fermentation and contains no animal-derived ingredients.
Sources
- UK Food Standards Agency: Approved Additives and E Numbers
- EU Regulation 1333/2008 on food additives (Annex II)
- EFSA NDA Panel, Scientific Opinion on Dietary Reference Values for niacin
- SACN, Report on Vitamins and Minerals
- UK Bread and Flour Regulations 1998 (as amended)
- Reder et al., New England Journal of Medicine, niacin and liver effects
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