Calcium gluconate
A calcium salt used to firm the texture of preserved fruit and vegetables, regulate acidity, and prevent discolouration in processed foods.
What is it?
Calcium gluconate is the calcium salt of gluconic acid, a mild organic acid that occurs naturally in honey, fruit juice, and wine. As a food additive it is produced by fermenting glucose with certain moulds or bacteria, then neutralising the resulting gluconic acid with calcium carbonate. It appears as a white, odourless powder.
What does it do?
It works in three ways depending on the food. As a firming agent, calcium ions cross-link pectin molecules in cell walls, keeping fruit and vegetables firm during canning or pickling. As a sequestrant, it binds free metal ions that would otherwise catalyse browning or off-flavours. As an acidity regulator, the gluconate anion buffers pH in products where tight pH control matters.
Where you will see it
Most commonly found in canned and jarred fruit and vegetables (tinned tomatoes, olives, pickled gherkins), some fruit-based desserts, and calcium-fortified plant-based drinks. Occasionally used in processed cheese and confectionery. On a UK label it appears as 'calcium gluconate' or 'E578'.
What the science says
Calcium and gluconate: how the body handles both parts
Once digested, calcium gluconate splits into calcium ions and gluconate. The calcium is absorbed through the gut wall and used or excreted by the kidneys exactly as calcium from dairy or vegetables would be. Gluconate is a naturally occurring metabolite already present in the body and is readily broken down. EFSA reviewed calcium gluconate as a nutrient source and concluded that both components are well characterised and do not present any novel metabolic pathway.
EFSA's Panel on Food Additives and Nutrient Sources assessed calcium gluconate as a source of calcium and found the bioavailability of calcium from it comparable to calcium from other food sources, with no grounds to restrict it at typical use levels.
No ADI assigned: what that means
EFSA did not set a numerical Acceptable Daily Intake for E578. This happens when a substance is chemically identical to compounds already present in food and the body, and the amounts used in food manufacturing are far below any level associated with harm. The absence of an ADI number is not a gap; it reflects that regulators did not consider one necessary.
No numerical ADI was established for calcium gluconate by EFSA because it consists of calcium and gluconate, both normal constituents of diet and metabolism, and intake from its use as an additive is considered nutritionally negligible.
Where it stands with the regulators
Who should be careful
People with hypercalcaemia (abnormally high blood calcium) are generally advised by their clinician to monitor all dietary calcium sources. Anyone in this situation should look for 'calcium gluconate' or 'E578' on labels. For everyone else, no specific avoidance is indicated.
The honest read
Calcium gluconate is one of the most chemically ordinary food additives in use. It is a calcium salt of an acid that already exists in fruit and honey. Regulators have reviewed it repeatedly and it has never attracted a restriction, warning label, or reduced permission. The science here does not have live disputes or unsettled questions.
Related additives
Common questions
Is E578 banned in the UK?
No. Calcium gluconate (E578) is an approved food additive in the UK under the assimilated EU Regulation 1333/2008, retained in UK law after Brexit. It is permitted in a range of preserved fruit and vegetable products and other categories.
Why is calcium gluconate added to canned vegetables?
Heat processing softens vegetables. Calcium ions from calcium gluconate bind to pectin in the cell walls and help keep the texture firmer after cooking and canning. This is the same principle as adding calcium chloride to pickles.
What foods contain E578?
Canned and jarred tomatoes, olives, pickled gherkins, other preserved vegetables, and some calcium-fortified plant-based drinks are the most common sources. It can also appear in certain processed cheese products and confectionery.
Is E578 vegan?
Yes. Calcium gluconate is produced by microbial fermentation of glucose, a fully plant-derived process. It contains no animal-derived ingredients.
Sources
- UK FSA: Approved additives and E numbers
- Regulation (EC) No 1333/2008 on food additives (EUR-Lex)
- EFSA Panel on Food Additives and Nutrient Sources (ANS): Safety of calcium gluconate as a source of calcium
See this on every food you scan
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
Get NutraSafe on the App Store