Is Food-Grade Calcium Sulfate Okay to Eat?

November 1, 2025 •

3 min read

According to the U.S. Food and Drug Administration (FDA), food-grade calcium sulfate has a "Generally Recognized as Safe" (GRAS) status and is approved for use as a food additive. So, is food-grade calcium sulfate okay to eat? The answer is yes, when consumed in moderation within regulated food products. This mineral, also known as gypsum, plays several roles in food production, from firming tofu to enriching calcium content.

Quick Summary

Food-grade calcium sulfate, also known as gypsum, is a safe and commonly used food additive approved by major regulatory bodies. It functions as a coagulant, firming agent, and nutrient supplement in many foods, including tofu and baked goods. High-purity sourcing is crucial to avoid harmful impurities found in industrial-grade versions.

Key Points

Food-Grade Safety: Food-grade calcium sulfate is considered safe for consumption by major regulatory bodies, including the FDA.
Functional Additive: It serves multiple purposes in food, such as a firming agent, coagulant, and dough conditioner.
Tofu Production: A key use is as a coagulant in tofu manufacturing, where it helps solidify soy milk.
Calcium Enrichment: It is added to various foods and beverages to increase their calcium content for nutritional fortification.
Purity Matters: It is crucial to distinguish between food-grade calcium sulfate and industrial-grade gypsum, as the latter is not safe to eat due to potential impurities.
Moderate Consumption: Excessive intake could lead to mild gastrointestinal discomfort, though this is rare with typical food consumption.

What Exactly is Food-Grade Calcium Sulfate?

Calcium sulfate, or gypsum, is a naturally occurring mineral compound composed of calcium and sulfate. For use in food, it is specifically processed to meet high purity standards and is labeled as "food-grade". It is distinct from industrial-grade gypsum used in construction materials like drywall, which contains impurities and is not safe for consumption. The FDA recognizes food-grade calcium sulfate as a safe food additive under the GRAS designation.

Culinary and Manufacturing Uses

As a versatile food additive (listed as E516 in Europe), food-grade calcium sulfate is utilized for its various functional properties in a wide range of products.

Functions of Calcium Sulfate in Food

Coagulant: In the production of tofu, calcium sulfate is added to heated soy milk to coagulate the soy proteins, which solidifies into a block of tofu. It produces a tofu with a tender, brittle texture.
Firming Agent: For canned fruits and vegetables, it helps maintain firmness and prevents the product from becoming too soft during processing.
Dough Conditioner: In commercial baking, calcium sulfate is added to dough to strengthen it, improve texture, and provide a stable structure.
Yeast Food: It acts as a nutrient for yeast, aiding the leavening process in baked goods.
Calcium Fortification: With a high calcium content, it is used to enrich the nutritional value of foods and beverages, especially for plant-based alternatives.

Comparison of Food-Grade and Industrial-Grade Calcium Sulfate


Feature	Food-Grade Calcium Sulfate	Industrial-Grade Calcium Sulfate
Purity	High purity, non-toxic, and free from harmful impurities like heavy metals.	Lower purity, may contain contaminants unsuitable for consumption.
Source	Sourced from high-purity natural gypsum deposits or synthetically produced under strict controls.	Can be sourced from various mineral deposits and industrial byproducts without strict food-safe processing.
Regulation	Regulated by food safety authorities like the FDA (GRAS status) and EFSA (E516).	Subject to industrial safety standards, not food consumption regulations.
Usage	Used in food processing, pharmaceuticals, and dietary supplements.	Used for construction (drywall), agriculture (soil conditioner), and other non-food applications.
Safety	Considered safe for consumption in regulated amounts.	Unsafe for human consumption due to potential impurities.

Is there any risk involved with eating calcium sulfate?

While food-grade calcium sulfate is considered safe, consuming excessively large amounts could potentially cause mild gastrointestinal issues like bloating, constipation, or diarrhea. These effects are rare and typically occur only with very high intakes far beyond what is found in standard food applications. Individuals with existing sensitivities or specific allergies should exercise caution, as with any substance. The primary risk is not from food-grade products but from accidentally ingesting industrial-grade gypsum, which is not intended for human consumption and can contain unsafe levels of impurities.

Conclusion

Food-grade calcium sulfate is a safe and beneficial ingredient used widely in the food industry. Its roles as a firming agent, coagulant, and calcium fortifier are critical for producing many common food items, from firm tofu to improved baked goods. The key to its safety lies in its high-purity, food-specific processing that distinguishes it from industrial-grade versions. As long as you are consuming regulated, food-grade products, incorporating items containing this additive as part of a balanced diet poses no significant health risks.

How does food-grade calcium sulfate differ from industrial-grade gypsum?

Food-grade calcium sulfate is processed to extremely high purity standards, free from toxic impurities, and approved by food safety authorities like the FDA and EFSA. In contrast, industrial-grade gypsum is not purified to this extent and is unsafe for human consumption, used only for construction and other non-food applications.

Frequently Asked Questions

Yes, calcium sulfate is the chemical compound name for the mineral commonly known as gypsum. However, only specifically purified, food-grade gypsum is safe for consumption.

It is added for a variety of functional reasons, including firming canned vegetables, acting as a coagulant for tofu and cheese, strengthening dough, and fortifying products with calcium.

Consuming it in the small, regulated amounts found in food products is safe. Very excessive intake, far beyond normal dietary levels, could potentially cause minor gastrointestinal issues like bloating or diarrhea, though this is uncommon.

The EPA and other health organizations have found no significant risk from food-grade calcium sulfate for the general population, including infants and children. However, pregnant individuals with concerns should consult a doctor.

In Europe, food-grade calcium sulfate is labeled as E516, which signifies its approval as a safe food additive.

Yes, high-purity, food-grade calcium sulfate is often used in the processing of organic foods, including beverages, baked goods, and tofu, as it can be sourced naturally.

It is primarily sourced from natural, mined gypsum deposits and is then processed to meet the high purity standards required for food use.