Last reviewed: October 2026.
Sodium benzoate is in most diet sodas, most fruit-flavored drinks, pickles, salad dressings, and a lot of sauces. It’s one of the oldest preservatives in the food supply, it’s safe at the amounts used, and it has one well-documented problem that is both real and narrow: in the presence of vitamin C, heat, and light, it can form benzene, a known carcinogen. That reaction, not the preservative itself, is why the FDA tested 200 beverages in 2006 and why several brands quietly reformulated. Here’s what sodium benzoate is, what the benzene issue actually involves, which products have the risky combination, and what else the research says.
Quick answer: is sodium benzoate bad for you?
Not at the levels in food. Sodium benzoate is the sodium salt of benzoic acid, which occurs naturally in cranberries and cinnamon; regulators set the acceptable daily intake at 5 mg per kg of body weight, and a can of diet soda delivers a small fraction of that. The one real concern is benzene: sodium benzoate plus ascorbic acid (vitamin C) plus heat or light can produce it in trace amounts. That combination is the thing to look for on a label — benzoate and ascorbic or erythorbic acid together — and it’s mostly been engineered out of major brands since 2007. On its own, in a cola or a pickle, sodium benzoate is low on the list of things to worry about.
Jump to: What it is · The benzene reaction · Products that have it · What the research says · Sodium vs. potassium benzoate · Verdict · FAQ
What sodium benzoate is
Benzoic acid is a natural antimicrobial — it’s what keeps cranberries from rotting on the bush. Sodium benzoate (E211) is benzoic acid neutralized with sodium so it dissolves in water, which lets manufacturers add it to drinks. It works by slipping into bacterial and mold cells in acidic conditions and disrupting their metabolism, which is why it’s only used in acidic products (pH below about 4.5): sodas, juices, pickles, dressings. In a neutral product it does nothing.
Your body handles it efficiently. Benzoate is bound to the amino acid glycine in the liver, becomes hippuric acid, and leaves in urine within hours — a pathway so reliable that sodium benzoate is used as a prescription drug to clear ammonia in people with urea-cycle disorders, at doses hundreds of times higher than food provides.
The benzene reaction
This is the whole reason the ingredient has a reputation. In 1990 industry chemists found that in a drink containing both sodium benzoate and ascorbic acid, exposed to heat or light, a small amount of the benzoate loses a carbon and becomes benzene. The reaction needs all three conditions; it’s accelerated by trace metals (copper, iron) in the water, which is why many sodas add EDTA to bind those metals.
Benzene is a known human carcinogen (IARC Group 1), linked to leukemia at occupational exposures. The amounts formed in drinks are tiny — measured in parts per billion — and the relevant comparison is the EPA’s drinking-water limit of 5 ppb. The FDA surveyed about 200 beverages between 2005 and 2007. Most were below 1 ppb; a handful, mostly diet fruit-flavored drinks, exceeded 5 ppb, one by a wide margin, and those products were reformulated. A follow-up found all retested products below the limit. The FDA’s position is that benzene at these levels doesn’t pose a safety concern; the practical takeaway is that the combination is avoidable, so there’s no reason to drink it.
Products that have it
The thing to check isn’t whether sodium benzoate is present — it’s whether it’s paired with ascorbic acid, erythorbic acid (a vitamin C relative), or “vitamin C” on the same label. Among the drinks we’ve broken down:
| Product | Benzoate | Ascorbic / erythorbic acid | Benzene pairing? |
|---|---|---|---|
| Diet Coke | Potassium benzoate | No | No |
| Coke Zero | Potassium benzoate | No | No |
| Sprite | Sodium benzoate | No | No |
| Dr Pepper | Sodium benzoate | No | No |
| Fanta | Sodium benzoate | No | No |
| Sunkist | Sodium benzoate | No | No |
| Mountain Dew | Sodium benzoate | Erythorbic acid | Yes (with EDTA to limit it) |
| Monster | Benzoic acid | No | No |
| Coca-Cola, Pepsi, 7 Up | None | No | No |
Outside soda, the pairing shows up in some fruit juices and juice drinks “with vitamin C,” some flavored waters, and some kids’ drinks — the exact category the FDA’s survey flagged. Those are where reading the label matters.
What the research says
Benzene formation Real, narrow
Established chemistry, confirmed by the FDA’s survey, largely engineered out of major brands. The risk is specific to the benzoate-plus-ascorbate pairing and is reduced by EDTA, cold storage, and keeping products out of light.
Hyperactivity in children Part of a mixture
Sodium benzoate was in both additive mixtures in the 2007 Southampton trial that found increased hyperactivity in children — but it was paired with synthetic dyes in both, so the study can’t separate the benzoate’s contribution from the dyes’. The EU’s 2010 warning label applies to the dyes, not benzoate. Our synthetic food dyes breakdown covers the study.
Cell and animal studies Weak
A 1999 yeast study found sodium benzoate damaged mitochondrial DNA; it got press in 2007 but has little bearing on humans at dietary doses. More recent cell-culture work on inflammation and oxidative stress uses concentrations far above what food delivers. Nothing here has changed any regulator’s assessment.
Allergy and sensitivity Rare, real
Benzoates can trigger hives or worsen asthma in a small number of people, particularly those with aspirin sensitivity or chronic urticaria. Documented; uncommon.
Regulatory status Approved everywhere
GRAS in the U.S.; EFSA re-evaluated benzoates in 2016 and set a group ADI of 5 mg/kg/day, noting most consumers stay well under it. The EU’s limit in soft drinks is 150 mg/L; typical U.S. use is similar or lower.
Sodium benzoate vs. potassium benzoate
Same molecule, different salt. Coca-Cola uses potassium benzoate in its diet colas to keep the sodium content down; the preservative action and the benzene chemistry are identical. If a product lists potassium benzoate, treat it exactly as sodium benzoate for every purpose above. Benzoic acid itself (on Monster’s label) is the same again.
Is sodium benzoate bad for you?
FittBeat verdict
Safe on its own; check what it’s next to. As a preservative in cola or pickles, sodium benzoate is among the least concerning things on a label — cleared quickly, used at a fraction of its limit, and backed by a century of use. The benzene reaction is real, specific, and avoidable: look for ascorbic or erythorbic acid on the same label, and prefer products that don’t pair them. The sugar or sweetener in the same can is a far bigger question than the preservative.
Frequently asked questions
Is sodium benzoate a carcinogen?
No. Sodium benzoate itself is not classified as a carcinogen. Benzene, which can form from it in the presence of vitamin C, heat, and light, is. The amounts formed in drinks are in parts per billion; the FDA tested about 200 beverages and reformulated the few that exceeded the drinking-water limit.
Which drinks contain sodium benzoate and vitamin C together?
Among major sodas, Mountain Dew (sodium benzoate plus erythorbic acid) is the main one. The pairing is more common in fruit juices and juice drinks fortified with vitamin C, and in some flavored waters. Check for ascorbic or erythorbic acid alongside a benzoate.
Is sodium benzoate natural?
Benzoic acid occurs naturally in cranberries, prunes, cinnamon, and cloves. Commercial sodium benzoate is made synthetically but is the same molecule.
How much sodium benzoate is safe?
The acceptable daily intake is 5 mg per kg of body weight — about 340 mg a day for a 150 lb adult. A 12 oz soda typically contains 30–60 mg.
Is potassium benzoate safer than sodium benzoate?
Same preservative, same chemistry, less sodium. Neither is safer; the choice is about the sodium content of the product.
Does sodium benzoate cause hyperactivity?
It was in the 2007 Southampton trial’s additive mixtures, but combined with synthetic dyes, so its individual contribution couldn’t be separated. The EU’s resulting warning label applies to the dyes.
Why do some sodas not have sodium benzoate?
Regular Coke and Pepsi have enough sugar and acid to be self-preserving. Diet sodas and clear citrus sodas spoil more easily and need a preservative. 7 Up uses a chelating agent (EDTA) instead.
Sources
- U.S. FDA. Data on benzene in soft drinks and other beverages (2005–2007 survey and follow-up). fda.gov
- U.S. FDA. Questions and answers on the occurrence of benzene in soft drinks and other beverages. fda.gov
- Gardner LK, Lawrence GD. Benzene production from decarboxylation of benzoic acid in the presence of ascorbic acid and a transition-metal catalyst. Journal of Agricultural and Food Chemistry, 1993. doi:10.1021/jf00029a001
- EFSA. Scientific opinion on the re-evaluation of benzoic acid (E 210), sodium benzoate (E 211), potassium benzoate (E 212) and calcium benzoate (E 213) as food additives. EFSA Journal, 2016. doi:10.2903/j.efsa.2016.4433
- McCann D, et al. Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community. The Lancet, 2007. doi:10.1016/S0140-6736(07)61306-3
- IARC. Benzene. IARC Monographs, Volume 120, 2018 (Group 1).
- U.S. EPA. National primary drinking water regulations: benzene maximum contaminant level, 5 ppb. epa.gov
This article is for informational purposes and is not medical advice. Talk to a doctor or registered dietitian about your individual nutrition needs.
