What is E237?

Complete guide to understanding sodium formate in your food

The Quick Answer

E237 is sodium formate, a preservative derived from formic acid used primarily in animal feed and some beverages to inhibit bacterial growth.

It prevents spoilage by stopping microorganisms from multiplying in food, especially in wet feeds and processed beverages.

While commonly used in animal feed throughout Europe, it appears less frequently in human food compared to other preservatives.

What Exactly Is It?

E237 is sodium formate, the sodium salt of formic acid. It appears as a white, slightly deliquescent (moisture-absorbing) crystalline powder with a faint formic acid odor. The chemical formula is HCOONa.

The name comes from its composition: it’s formic acid (the simplest carboxylic acid) combined with sodium hydroxide. Formic acid is naturally found in ant venom and nettle stings, though the sodium formate used in food is manufactured synthetically.

In chemical terms, sodium formate is the sodium salt of a weak organic acid. When dissolved in water, it functions as a pH buffer and antimicrobial agent. Unlike pure formic acid, which is highly corrosive, sodium formate is significantly less aggressive and safer to handle, though still mildly irritating to eyes and respiratory systems.

Where You’ll Find It

E237 appears in a relatively limited range of foods compared to other preservatives:

– Animal feed (most common use—silage, poultry feed, swine feed)
– Some fruit juices
– Non-alcoholic beverages
– Preserved vegetables
– Certain pickled products
– Some processed animal products

It’s important to note that E237 is used much more extensively in animal feed than in human food. The European Union restricts its use in human food more than in animal feed, which means you’re less likely to encounter it in everyday consumer products compared to preservatives like E202 (potassium sorbate) or E211 (sodium benzoate).

Why Do Food Companies Use It?

E237 serves a specific but important function, particularly in animal feed:

1. Inhibits bacterial growth: The formate ion (HCOO⁻) has antimicrobial properties that prevent bacteria, molds, and other microorganisms from growing. This is the primary reason for its use.

2. Prevents spoilage in feed: E237 is especially useful in animal feed because it keeps wet or moist feedstuffs fresh longer. Silage, poultry feed, and swine feed can contain moisture that promotes microbial growth, and E237 prevents this.

3. Extends shelf life in beverages: In fruit juices and non-alcoholic drinks, it preserves freshness by stopping fermentation and microbial spoilage.

4. Provides pH control: Sodium formate buffers pH, preventing foods from becoming too acidic or too basic, which affects both safety and flavor.

5. Works at lower concentrations than some alternatives: E237 can be effective at relatively modest levels, reducing the amount of preservative needed.

Why isn’t it used more in human food? Several factors limit its use: it’s mildly irritating to eyes and airways (unlike potassium sorbate or sodium benzoate), it can affect flavor in some applications, and regulatory authorities have restricted its approved uses in human food compared to animal feed. Therefore, food manufacturers typically choose other preservatives for consumer products.

Is It Safe?

The official position: E237 is approved as safe by regulatory bodies, though with specific use restrictions.

The European Food Safety Authority (EFSA) has evaluated sodium formate and approved its use as a preservative. The FDA and JECFA (Joint FAO/WHO Expert Committee) have also assessed it as safe. However, the EU restricts its use in human food more than in animal feed, suggesting a more cautious approach.

Regarding Acceptable Daily Intake (ADI): Sources indicate an ADI of approximately 3 mg per kilogram of body weight per day for humans, though regulatory authorities primarily focus on its use in animal feed where an ADI of 10,000-12,000 mg formic acid equivalents per kilogram of complete feed is considered safe.

Important safety considerations:

At very high concentrations or in large acute doses, formic acid (the parent compound) can cause serious effects including gastrointestinal distress, metabolic acidosis, and eye/respiratory irritation. However, these effects occur at far higher levels than would be consumed through normal food consumption. The safety assessment research shows that:

– Sodium formate is rapidly absorbed and eliminated from the body (within 45-46 minutes)
– Normal food consumption levels do not cause adverse effects
– It is not carcinogenic or mutagenic at approved use levels
– The amounts used in food are carefully controlled

Areas of concern that researchers have identified:

Animal studies at very high doses (far exceeding food use levels) showed that formic acid can cross the placenta and potentially affect fetal development. However, these effects were only observed at doses vastly exceeding what anyone would consume from food additives. The restriction of E237 in human food (compared to animal feed) reflects regulatory conservatism rather than demonstrated human health risks.

Natural vs Synthetic Version

E237 is essentially always a synthetic product in food applications:

Synthetic version: Manufactured by neutralizing formic acid with sodium hydroxide. This is how all food-grade sodium formate is produced for commercial use.

Naturally-derived version: While formic acid exists naturally (in ant venom, nettles, and some fermented foods), sodium formate is not practically extracted from natural sources for food use. It’s always synthesized.

There is no meaningful “natural vs synthetic” distinction for E237—all commercial sodium formate used in food is synthesized through controlled chemical processes.

Natural Alternatives

Want to avoid E237?

Food manufacturers sometimes use these alternative preservatives:

– E200-E203 (Sorbic acid and sorbates) – derived from berries, very common
– E210-E213 (Benzoic acid and benzoates) – natural but also synthetic, widely used
– E202 (Potassium sorbate) – gentler alternative, widely used
– E260-E263 (Acetic acid and acetates) – from vinegar fermentation
– E270 (Lactic acid) – from fermented foods
– Rosemary extract – natural antioxidant
– Salt-based preservation – traditional method

These alternatives are more commonly used in human food than E237, which is why you’re far more likely to encounter them on ingredient labels. They’re often preferred because they lack the eye and respiratory irritation potential of formic acid derivatives.

The Bottom Line

E237 (sodium formate) is an approved preservative used primarily in animal feed and occasionally in some beverages. Regulatory bodies worldwide have determined it’s safe for the approved uses at permitted levels.

The key distinction with E237 is that it’s much more extensively used in animal feed than in human food. This likely reflects both practical considerations (eye/respiratory irritation, flavor effects) and regulatory conservatism rather than serious safety concerns.

For most people, E237 appears infrequently in their diet because its use in human food is limited and other preservatives are preferred in most applications.

What you should do:

– Understand that E237 is an approved preservative with restricted use in human food
– Don’t be concerned if you encounter it occasionally in beverages or preserved products—it’s used at safe levels
– Read labels if you want to identify products containing it
– Know that it’s used much more extensively in animal feed than consumer products
– Remember that regulatory approval reflects genuine safety at approved use levels

E237 is a legitimate preservative that plays a role in food safety, particularly in animal feed where it’s extensively used. While less common in human food than many other preservatives, it’s approved and considered safe at permitted levels by all major regulatory authorities.