Ascorbic Acid (E300, Vitamin C)

What is ascorbic acid and what is it used for?

Ascorbic acid is vitamin C, which the human body cannot make itself and must get from food. It is needed for connective tissue, immunity and iron absorption. In industry it is usually made from glucose obtained from sources such as maize or wheat; ascorbic acid produced in the laboratory is chemically identical to the vitamin C in fruit.

Its main role as a food additive is to protect other ingredients by reacting with oxygen: it slows the browning of cut fruit and fruit juice, the rancidity of fats and loss of colour. In bread-making it is also used as a flour treatment agent to strengthen the dough. Its salts sodium ascorbate (E301) and calcium ascorbate (E302), and the fat-soluble ascorbyl palmitate (E304), are used for the same purposes.

Which products contain it?

• Fruit juices, nectars and fruit drinks
• Canned and frozen fruit and vegetables
• Cured meat products such as sucuk (spicy sausage), salami and sausages (as ascorbate)
• Bread and flour products (as a flour treatment agent)
• Baby foods, breakfast cereals and vitamin-fortified products

Is it harmful? The scientific assessment

EFSA has re-evaluated ascorbic acid and its salts and concluded that there is no safety concern at the amounts used as food additives. Excess vitamin C is largely excreted in urine.

Ascorbate has a particular benefit in processed meats: it reduces the formation of nitrosamines when sodium nitrite reacts with amines in the meat. This is why manufacturers use ascorbate together with nitrite.

One known rare interaction is that when ascorbic acid and sodium benzoate are present in the same drink and the product is exposed to heat or light, trace amounts of benzene can form. This has been examined by regulators, and manufacturers have adjusted their formulations accordingly; even so, storing such drinks in a cool, dark place is a good habit.

Who should be careful?

• People with a history of kidney stones: The amounts in food cause no problems; however, long-term high-dose vitamin C supplements may increase the risk of stones in some people. You can discuss supplement use with your doctor.
• People with iron overload disease (haemochromatosis): Because vitamin C increases iron absorption, a doctor's opinion on high-dose supplements is important.
• People with a sensitive stomach: Because it is acidic, high doses can cause stomach upset in some people.

What to do when you see it on a label

Seeing E300 or “antioxidant (ascorbic acid)” on a label is no cause for concern; on the contrary, it shows that the product is protected against oxidation. However, a product having “added vitamin C” does not automatically make it healthy; adding vitamin C to a sugary drink does not change its sugar content. Getting your vitamin C from fresh fruit and vegetables is always the best way.