E285 - Sodium tetraborate (borax)

At a glance

• Also called borax, sodium borate, or disodium tetraborate; E-number E285.
• Not permitted for use in foods in the U.S. or EU; it should not appear on ingredient lists there.
• Historically used as a preservative and firming agent, but replaced by safer, approved additives.
• Common outside the kitchen in detergents, glassmaking, and other industrial uses.

Why is sodium tetraborate (borax) added to food?

Borax was historically used to slow spoilage and help firm delicate foods like fish roe. It can inhibit some microbial growth and alter texture, which is why it showed up in old caviar-processing practices.¹ In current regulated markets, these roles are covered by approved preservatives and firming agents, so there is no authorized food use for borax.²

What foods contain sodium tetraborate (borax)?

In the United States and the European Union, foods should not contain E285. It is listed by the U.S. Food and Drug Administration (FDA) among substances prohibited in human food.¹ Under EU rules, only additives included in the Union list may be used in foods placed on the market, and sodium tetraborate is not on that list.²

What can replace sodium tetraborate (borax)?

Food makers use safer, approved ingredients to achieve the same goals:

• For preservation: sorbic acid, potassium sorbate, or sodium benzoate in permitted foods and levels.
• For acidity control and mild preservative effects: citric acid.
• For firming/crisping in select foods: calcium chloride. Exact choices depend on the food, local regulations, and labeling needs.

How is sodium tetraborate (borax) made?

Commercial borax typically comes from natural borate minerals (such as tincal) or brines. Producers refine these sources and often react boric acid with sodium carbonate to form sodium tetraborate, which may be sold as the decahydrate “borax” crystals.³ The compound is widely used in glass and ceramics, detergents, and other non-food applications.³

Is sodium tetraborate (borax) safe to eat?

Regulators do not allow borax in foods in the U.S., and it is not authorized as a food additive in the EU.¹² Toxicological reviews of boron compounds (the chemical family that includes borax) note concerns about reproductive and developmental effects at elevated exposures, which is one reason regulators have taken a precautionary approach for food uses.⁴ Nutrition authorities also set upper intake levels (ULs) for total boron from all sources to help limit risk; for adults, the U.S. National Institutes of Health cites a UL of 20 mg/day of boron, not specific to any one compound.⁵

Does sodium tetraborate (borax) have any benefits?

In food, there is no recognized nutritional benefit, and it is not an approved additive in the U.S. or EU.¹² Its technological effects (preserving and firming) are now achieved using safer, permitted additives tailored to each food.

Who should avoid sodium tetraborate (borax)?

• Consumers in the U.S. and EU should avoid foods containing borax because it is not permitted for use in food there.¹²
• Groups sensitive to boron exposure, such as infants, young children, and people who are pregnant or may become pregnant, should be especially cautious; toxicology reviews highlight developmental and reproductive risks from excessive boron intake.⁴

Myths & facts

• “Borax is natural, so it’s safe to eat.” Natural origin doesn’t guarantee safety; regulatory agencies judge safety by evidence, not by source.¹
• “Borax and boric acid are the same thing.” They are closely related boron compounds but not identical. Both are not allowed as food additives in the U.S., and boric acid (E284) is likewise not authorized in the EU for food use.¹²
• “If it was used in traditional foods, it must be fine.” Historic use does not meet modern safety standards; approved alternatives now perform the same roles with better safety margins.²

Sodium tetraborate (borax) in branded foods

You should not see sodium tetraborate, borax, sodium borate, or disodium tetraborate on ingredient lists of foods sold in the U.S. or EU. If encountered on older labels or products from outside these markets, consider choosing a product that uses permitted alternatives such as sorbic acid, potassium sorbate, or citric acid.

References

Footnotes

1. Food Additive Status List — U.S. Food and Drug Administration (FDA). https://www.fda.gov/food/food-additives-petitions/food-additive-status-list ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

2. Regulation (EC) No 1333/2008 on food additives (Union list framework) — EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32008R1333 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

3. Mineral Commodity Summaries: Boron — U.S. Geological Survey (USGS). https://pubs.usgs.gov/periodicals/mcs2023/mcs2023-boron.pdf ↩ ↩²

4. Toxicological Profile for Boron — Agency for Toxic Substances and Disease Registry (ATSDR), U.S. CDC. https://www.atsdr.cdc.gov/toxprofiles/tp26.pdf ↩ ↩²

5. Boron — NIH Office of Dietary Supplements (Health Professional Fact Sheet). https://ods.od.nih.gov/factsheets/Boron-HealthProfessional/ ↩