What is E300?
Ascorbic acid — the same Vitamin C found in oranges, used in packaged food as a preservative and antioxidant. Considered low-risk on its own, but one common combination has a genuine asterisk attached.
E300 is ascorbic acid, better known as Vitamin C. It's added to food as an antioxidant, preservative and colour stabiliser, and is one of the most well-tolerated additives in use — naturally-derived or synthetic, it's considered chemically equivalent either way. Goodnessly rates it Caution, mainly because of a well-documented reaction it can have with certain preservatives, not because of the ingredient itself.
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Read the FAQ →
What is ascorbic acid?
Ascorbic acid is Vitamin C — the same core compound whether it comes from an orange or a factory. As a food additive it's valued less for its nutritional role and more for its chemistry: it's a powerful antioxidant, meaning it reacts with oxygen before your food's fats, colours and flavours can. Commercial ascorbic acid is usually made by chemical synthesis or fermentation rather than extracted from fruit, purely because it's cheaper at scale — the end product is considered chemically equivalent either way.
What's it used for?
- Antioxidant — stops fats and oils in food going rancid, and stops cut fruit and vegetables browning
- Preservative — extends shelf life by slowing oxidation
- Colour stabiliser — keeps processed meats looking pink/red rather than greying
- Flour treatment agent — improves dough structure in baking
- Acidity regulator — adjusts the tartness of drinks and foods
Where you'll find 300 on the shelf
Ascorbic acid is one of the most widely used additives around — you'll find it in almost every aisle.
Is ascorbic acid safe? What the research says
On its own, ascorbic acid is one of the most extensively studied and well-tolerated substances in food science — it's the same molecule your body needs from diet anyway. Regulatory status reflects that:
| Region | Status | What this means |
|---|---|---|
| AU/NZ Australia & New Zealand (FSANZ) | Permitted, no limit | Permitted in all foods with no maximum level, except infant formula, which is capped at 300mg per kilogram. |
| EU European Union (EFSA) | Permitted, no ADI | Listed as E300. EFSA has not set a formal Acceptable Daily Intake, meaning it's considered safe without a numerical daily limit — one of a small number of additives treated this way. |
| US United States (FDA) | GRAS | Holds Generally Recognized As Safe (GRAS) status, the FDA's highest confidence category for a food ingredient. |
The genuine caveat isn't ascorbic acid itself, but what it can do when combined with certain other preservatives. See "Recent developments" below.
- The benzoate reaction: since 1990, the FDA has known that ascorbic acid can react with benzoate preservatives (sodium or potassium benzoate, E211/E212) to form small amounts of benzene, a known carcinogen, especially when the product is exposed to heat or light. This came under renewed scrutiny in 2005–2006 when testing found benzene above drinking-water safety limits in a number of diet soft drinks. Most major beverage manufacturers reformulated their products to avoid the combination once this became public.
- Why this affects the rating, not just the drink: ascorbic acid used alone — in fruit juice, jam, or as a straightforward antioxidant — doesn't carry this risk. It's specifically the combination with benzoate preservatives, plus heat or light exposure, that matters. This is why Goodnessly checks each product's actual ingredient combination rather than rating ascorbic acid as uniformly safe or unsafe.
This section is checked periodically rather than continuously — if you're reading this well after the date above, it's worth confirming nothing has changed before citing it.
Who this matters to
- Anyone who drinks diet soft drinks regularly — specifically ones that list both a benzoate preservative (211/212) and ascorbic acid or Vitamin C
- Anyone storing drinks in hot conditions (a hot car, direct sun) for extended periods, since heat is one of the triggers for the reaction
- There's generally no reason to avoid ascorbic acid in fruit juice, jam, or foods without a benzoate preservative present
Goodnessly rates E300 Caution rather than Safe, reflecting that its safety genuinely depends on what else is in the product with it — not a concern with the ingredient itself. Most manufacturers reformulated to avoid this combination once it became public, so it's less common today than it was in the mid-2000s, but it hasn't disappeared entirely.
How to spot it on a label
Ascorbic acid is usually declared clearly, since it doubles as a recognised nutrient. Look out for:
- Ascorbic acid
- 300 or E300
- Vitamin C
- "Antioxidant (300)" in the ingredients list
To check for the benzoate combination specifically, also look for sodium benzoate, potassium benzoate, 211, 212, E211 or E212 on the same label.
Related additives
Frequently asked questions
Is E300 the same as Vitamin C?
Yes — 300 (or E300) is the additive code for ascorbic acid, which is Vitamin C. There's no chemical difference between the E300 on a food label and the Vitamin C in a supplement or an orange.
Is ascorbic acid natural or synthetic?
It can be either. Ascorbic acid used as a food additive is usually made by chemical synthesis or fermentation rather than extracted from fruit, mainly because it's far cheaper to produce that way at scale. Either version is considered chemically equivalent and is absorbed by the body in the same way.
Can ascorbic acid form a carcinogen?
Not on its own. But when combined with a benzoate preservative (sodium or potassium benzoate, 211/212) and exposed to heat or light, a reaction can produce small amounts of benzene, a known carcinogen. The FDA has tracked this since 1990, and most major manufacturers reformulated their products after it drew public attention in 2005–2006. It's a combination effect, not a property of ascorbic acid by itself.
Does Goodnessly rate E300 as safe, caution, or avoid?
Goodnessly rates E300 (Ascorbic Acid) as Caution. On its own it's one of the most well-tolerated additives in use, with no formal daily intake limit set by regulators. The caution reflects its potential to react with benzoate preservatives under certain conditions, which is a real but avoidable combination, not a hazard of the ingredient itself.
Is E300 safe for children?
Yes, at the levels used in food — it's the same substance found naturally in fruit that children are encouraged to eat. The only specific regulatory limit is in infant formula, which caps added ascorbic acid at 300mg per kilogram, a precaution rather than a response to any identified risk.
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Scan any product with the Goodnessly app to instantly see its full additive breakdown — including whether any combination, like ascorbic acid with a benzoate preservative, is worth a second look.
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