E-numbers / Antioxidants / E302
also: Calcium salt of ascorbic acid · Vitamin C (calcium form)
The calcium salt of vitamin C, used to stop fats and colours from going rancid or fading in food.
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Re-evaluated with ascorbic acid (E300) and sodium ascorbate (E301); very low acute toxicity, no genotoxicity concern, no need for a numerical ADI
Why it’s worth knowing. Re-evaluated with ascorbic acid (E300) and sodium ascorbate (E301); very low acute toxicity, no genotoxicity concern, no need for a numerical ADI
Calcium ascorbate is the calcium salt of ascorbic acid, the chemical form of vitamin C. It is a white to slightly yellowish crystalline or powder substance that dissolves readily in water. Because it combines a buffered form of vitamin C with a small amount of calcium, it is sometimes used in supplements as a gentler alternative to straight ascorbic acid. As a food additive it functions identically to vitamin C itself.
It works by donating electrons to oxidising agents before they can attack the pigments, fats or other sensitive molecules in food. This prevents rancidity in oils and fats, stops cut fruit from browning, and protects colours from fading. It also maintains the potency of vitamin C in fortified products. In meat products it accelerates the curing process by reducing nitrates to nitrites more rapidly, which fixes the pink colour.
Found in processed and canned fruits and vegetables, fruit juices and nectars, tinned fish, cured and processed meats (such as cooked ham and bacon), breakfast cereals, fat-based spreads, confectionery, and some dietary supplements. On a UK label it appears as 'calcium ascorbate' or 'antioxidant (E302)'.
Calcium ascorbate releases ascorbic acid (vitamin C) in the body and is handled identically by human metabolism. Because vitamin C is a well-characterised essential nutrient, EFSA concluded in its 2015 re-evaluation that a numerical acceptable daily intake was unnecessary. At food-additive use levels the contribution to total vitamin C intake is modest and well within the range found in ordinary diets.
EFSA re-evaluated ascorbic acid (E300), sodium ascorbate (E301) and calcium ascorbate (E302) together and concluded that the data demonstrated no safety concern at current use levels in food; no numerical ADI was considered necessary.
Very large doses of vitamin C from all sources combined, typically from supplements rather than food additives, can increase oxalate excretion in urine. This has been linked to a raised risk of kidney stones in people prone to them. The amounts present in food from E302 as an additive are small and not the same order of magnitude as high-dose supplement use. The signal is relevant only at total daily vitamin C intakes well above what foods alone deliver.
High supplemental vitamin C intake (above 1000mg per day) increases urinary oxalate and has been associated with a higher risk of kidney stones in observational studies, particularly in men.
Vitamin C, including from ascorbate salts, markedly increases the absorption of non-haem iron from plant foods when consumed together. For most people this is nutritionally beneficial. In individuals with haemochromatosis (a genetic condition causing iron overload), consistently high vitamin C intake from any source can worsen iron accumulation.
Ascorbic acid enhances non-haem iron absorption by reducing ferric to ferrous iron in the gut, an effect well-established across multiple controlled studies.
People with hereditary haemochromatosis (iron-overload disorder) may want to be aware of total vitamin C intake from all sources, as it increases iron absorption. Those prone to calcium oxalate kidney stones should track their overall daily vitamin C intake across supplements and food. Look for 'calcium ascorbate' or 'E302' on the label.
Calcium ascorbate is, in practical terms, vitamin C bound to a small amount of calcium. It has been used in food for decades and the science around it is unusually complete compared with most additives, because vitamin C is among the most-studied nutrients in human biology. The 2015 EFSA review looked at the entire body of evidence and found no reason to set a maximum daily intake. The only genuinely relevant signals involve very high vitamin C intake from supplements, not from incidental additive use in food, and a specific concern for people with haemochromatosis around iron absorption. There is no active scientific dispute about E302 itself as a food additive.
No. Calcium ascorbate is authorised in England, Scotland and Wales under the UK FSA approved-additives list, carried over from EU Regulation 1333/2008. It is permitted across a wide range of food categories.
Yes. Your body absorbs the ascorbic acid released from calcium ascorbate in the same way as vitamin C from food or supplements. The amounts from additive use in food are generally small.
Canned and processed fruit and vegetables, fruit juices, cured meats such as cooked ham and bacon, tinned fish, breakfast cereals, fat-based spreads, and some confectionery. Check labels for 'calcium ascorbate' or 'antioxidant (E302)'.
Yes. Calcium ascorbate is produced synthetically from ascorbic acid and calcium compounds. It contains no animal-derived ingredients and is suitable for vegans and vegetarians.
Last reviewed: 20 June 2026
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