Calcium sulphate
A naturally occurring mineral salt used to firm up foods, strengthen flour, and control acidity. Found in bread, tofu, and processed foods.
What is it?
Calcium sulphate is the calcium salt of sulphuric acid. It occurs naturally as the mineral gypsum and is the same substance used to set tofu in traditional manufacturing. In food, it is a white odourless powder that carries calcium and sulphate ions.
What does it do?
Acts as a firming agent by cross-linking proteins and pectin in plant cell walls, helping foods hold their structure during processing. Also functions as a flour treatment agent by strengthening gluten networks in bread dough, as an acidity regulator, and as a raising agent component in baking powders. In tofu production, it causes soy proteins to coagulate into a solid curd.
Where you will see it
Bread and flour-based products (where it strengthens dough and improves texture), tofu and soy-based foods (as the traditional setting agent), canned vegetables and pulses (to keep them firm), processed cheese, breakfast cereals, and some ready meals. On a UK label it appears as calcium sulphate or E516.
What the science says
EFSA re-evaluation (2019)
The European Food Safety Authority completed a full re-evaluation of calcium sulphate as a food additive in 2019. The panel reviewed available toxicology data and concluded that exposure to E516 at permitted food use levels does not raise a safety concern. No numerical acceptable daily intake was considered necessary because the substance is a normal mineral component of the diet and the body regulates calcium and sulphate through established physiological pathways.
EFSA concluded that exposure to calcium sulphate at reported food use levels does not raise a safety concern and set no numerical ADI, noting the substance is a physiologically normal mineral salt.
Calcium and sulphate as dietary components
Calcium is an essential mineral required for bones, teeth, nerve function, and muscle contraction. Sulphate is a normal metabolite present in the body and in many foods. Both are regulated by the kidneys and excreted in urine when consumed in excess. The amounts of calcium and sulphate contributed by food additive use of E516 are small compared with background dietary intake from water, vegetables, and dairy.
Calcium is an essential nutrient with an established dietary reference value; the contribution from food additive E516 is minor relative to total dietary calcium intake.
Where it stands with the regulators
Who should be careful
People with hypercalcaemia (abnormally high blood calcium) are typically advised by clinicians to monitor total calcium intake from all sources, which would include foods manufactured with E516. Anyone managing kidney disease who has been told to limit dietary calcium or sulphate should check with their dietitian. The label term to look for is calcium sulphate or E516.
The honest read
Calcium sulphate is one of the most long-established mineral additives in food manufacturing. It has been used to make tofu for centuries and in bread baking for well over a hundred years. The 2019 EFSA re-evaluation, which is the most recent systematic review, found nothing in the toxicology data requiring a limit on intake. The substance is chemically straightforward: it delivers calcium and sulphate, both of which the body handles through normal mineral metabolism. There is no active scientific debate about this additive at typical food-use levels.
Related additives
Common questions
Is E516 banned in the UK?
No. Calcium sulphate is on the UK FSA approved-additives list and is permitted across a range of food categories under UK food law (assimilated EU Regulation 1333/2008).
Is the calcium in E516 the same as dietary calcium?
Yes. When calcium sulphate dissolves in food or in digestion it releases calcium ions and sulphate ions, both of which are handled by the body through normal mineral metabolism. The calcium counts toward your daily intake the same as calcium from dairy or vegetables.
What foods contain E516?
Bread and flour products, tofu, canned vegetables, processed cheese, some breakfast cereals, and baking powder are the most common sources. It may appear on the label as calcium sulphate or E516.
Is E516 vegan?
Yes. Calcium sulphate is a mineral compound with no animal-derived ingredients. It is commonly used in tofu production, which is a staple of vegan and vegetarian diets.
Sources
- EFSA Panel on Food Additives and Flavourings: Re-evaluation of sulphuric acid and its sodium, potassium, calcium and ammonium salts (E 513, 514, 515, 516, 517) as food additives, EFSA Journal 2019
- UK FSA: Calcium sulphate (E516) regulated product entry
- UK FSA: Approved additives and E numbers
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