Gamma-tocopherol
A synthetic form of vitamin E added to oils, fats and processed foods to stop them going rancid by neutralising harmful free radicals.
What is it?
Gamma-tocopherol is one of four tocopherol isomers (alpha, beta, gamma, delta) that together make up vitamin E. E308 is specifically the synthetic form, dl-gamma-tocopherol, produced from vegetable-oil distillation fractions or by chemical synthesis. Gamma-tocopherol is the predominant tocopherol in many vegetable oils such as soybean and corn oil, and occurs naturally in a wide range of plant foods. As a food additive it is chemically identical to the naturally occurring compound but may contain a mixture of stereoisomers (the dl- form) rather than the single d- form found in nature.
What does it do?
Gamma-tocopherol is a fat-soluble antioxidant. It works by donating a hydrogen atom to lipid peroxy radicals, breaking the chain reaction of lipid oxidation that turns fats rancid and produces off-flavours. Compared with alpha-tocopherol (E307), gamma-tocopherol is less potent as a vitamin E nutrient but is notably effective at trapping reactive nitrogen species such as peroxynitrite, giving it a slightly different antioxidant profile. In food, it protects unsaturated fatty acids in oils and fat-rich products from oxidative degradation during storage and processing.
Where you will see it
Most commonly added to vegetable oils, margarines, spreads, cooking fats, salad dressings, infant formula, dry breakfast cereals, snack foods, baked goods and ready meals containing added fat. It may also appear in nutritional supplements and fortified foods. On a UK ingredient label it appears as 'gamma-tocopherol', 'E308', or 'antioxidant (E308)'.
What the science says
EFSA re-evaluation: no concern at food-use levels
In 2015, the European Food Safety Authority's Panel on Food Additives and Nutrient Sources completed a full re-evaluation of synthetic gamma-tocopherol (E308) alongside the other tocopherol additives (E306-E309). The Panel concluded that tocopherols at the levels used in food are not of safety concern. No numerical acceptable daily intake was considered necessary because the compounds are normal dietary constituents and vitamin E metabolites.
EFSA concluded synthetic gamma-tocopherol (E308) is not of safety concern at levels used as a food additive; no numerical ADI was set for the tocopherol group.
Gamma-tocopherol versus alpha-tocopherol: different roles
Gamma-tocopherol differs from alpha-tocopherol in its side chain, which gives it weaker classical vitamin E activity but stronger ability to neutralise reactive nitrogen species. Research has investigated whether gamma-tocopherol has distinct anti-inflammatory properties in the body, separate from its antioxidant function in food. This research is preliminary and does not alter the food-additive assessment.
Gamma-tocopherol can trap and detoxify reactive nitrogen species such as peroxynitrite more efficiently than alpha-tocopherol, a property linked to potential anti-inflammatory effects in cell and animal studies.
Alpha-tocopherol supplementation can displace gamma-tocopherol from plasma, reducing circulating gamma-tocopherol concentrations; the clinical significance of this displacement at food-additive exposure levels is not established.
Synthetic (dl-) versus natural (d-) form
The E308 additive is the synthetic racemic mixture (dl-gamma-tocopherol), meaning it contains stereoisomers not found in nature alongside the natural form. Alpha-tocopherol research has established that synthetic dl-alpha-tocopherol has lower biological vitamin E activity than natural d-alpha-tocopherol. For gamma-tocopherol the practical difference in antioxidant food-protection function is not considered meaningful at additive use levels.
Synthetic dl-alpha-tocopherol has approximately 74% of the biological vitamin E activity of natural d-alpha-tocopherol; analogous stereoisomer differences exist for other tocopherol forms but are not considered safety-relevant at food additive levels.
Where it stands with the regulators
Who should be careful
No specific population group is required to avoid E308 at food-additive levels. People taking high-dose alpha-tocopherol supplements should be aware that high supplemental alpha-tocopherol can reduce blood gamma-tocopherol levels, but this is a supplement interaction, not a food-label concern. Look for 'E308' or 'gamma-tocopherol' in the ingredients list.
The honest read
Gamma-tocopherol is a normal component of many vegetable oils and plant foods. As a food additive (E308) it is the synthetic version of that same compound. The EFSA re-evaluation in 2015 found no grounds for concern at the quantities used in food. Some researchers are interested in whether gamma-tocopherol's ability to neutralise nitrogen-based free radicals gives it health benefits beyond basic antioxidant function, but that research is preliminary and separate from the question of whether the additive is a problem. There is no active regulatory concern, no campaigning body has flagged it, and it carries no warning requirement anywhere in the UK or EU.
Related additives
Common questions
Is E308 banned in the UK?
No. E308 gamma-tocopherol is approved for use in the UK under the assimilated EU Regulation 1333/2008, confirmed as of 31 December 2020 and applying in England, Scotland and Wales.
Is E308 the same as vitamin E?
Gamma-tocopherol is one of the eight compounds that collectively have vitamin E activity, but it is less potent than alpha-tocopherol (E307), which is the main form measured in vitamin E nutrition. As a food additive, E308 is present to protect the food from going rancid, not to provide a nutritional dose of vitamin E.
What foods contain E308?
E308 is most commonly added to vegetable oils, margarines, spreads, infant formula, breakfast cereals, baked goods, snacks and ready meals containing added fat. On the label it appears as 'gamma-tocopherol', 'E308', or 'antioxidant (E308)'.
Is E308 vegan?
Yes. Gamma-tocopherol (E308) is derived from vegetable-oil sources or produced synthetically, and contains no animal-derived ingredients. It is suitable for vegans and vegetarians.
Sources
- EFSA Panel on Food Additives and Nutrient Sources: Scientific Opinion on the re-evaluation of tocopherol-rich extract (E306), alpha-tocopherol (E307), gamma-tocopherol (E308) and delta-tocopherol (E309) as food additives. EFSA Journal 2015;13(6):4247
- UK FSA Regulated Products: E-308 Gamma-Tocopherol authorisation record
- UK Food Standards Agency: Approved additives and E numbers
- Jiang Q, Christen S, Shigenaga MK, Ames BN. Gamma-tocopherol, the major form of vitamin E in the US diet, deserves more attention. American Journal of Clinical Nutrition 2001;74(6):714-722
- Handelman GJ et al. Oral alpha-tocopherol supplements decrease plasma gamma-tocopherol levels in humans. Journal of Nutrition 1985;115(6):807-813
- Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academies Press, 2000
- European Commission: Food additives re-evaluation programme
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