Is Calcium Carbonate Vegan? A Dietitian’s Guide

Calcium carbonate is a common ingredient in supplements and foods, but is there a way to tell whether it’s vegan? Turns out the answer is a little complicated.

Fortunately, you’ve come to the right place!

In this post we will cover what calcium carbonate is, what products contain it, how to tell whether it’s vegan, and some additional information on calcium supplements and recommendations for vegans.

Learn more about calcium carbonate below.

Dish with calcium carbonate powder

What is calcium carbonate?

Calcium carbonate is a naturally occurring compound that contains two minerals, calcium and carbonate. It is naturally found as the main component of certain rocks, including limestone, chalk, and marble. Oyster shells and chicken eggshells are also naturally very high in calcium carbonate.

It can also be produced synthetically from carbon dioxide and calcium hydroxide through a chemical process called precipitation. Calcium carbonate produced this way is often used in making paper (1).

Calcium carbonate is used in some drugs and supplements, toothpaste, and is often added to foods to increase their calcium content or for use as an anticaking agent, firming agent, dough strengthener, pH stabilizer, or as a thickener to improve a food’s consistency (2).

Calcium carbonate is often added to foods because it is more easily absorbed in the body compared to other forms of calcium, such as calcium citrate (3).

The FDA has approved the use of calcium carbonate as a food additive and has designated it as Generally Recognized as Safe (GRAS) for this use (4).

Is calcium carbonate vegan?

The issue of whether calcium carbonate can be considered vegan gets somewhat complicated. According to the FDA Code of Federal Regulations (21 CFR 73.70), calcium carbonate as a food additive is described as a white powder “prepared either by grinding naturally occurring limestone or synthetically, by precipitation”.

Since most calcium carbonate used in food and commercial calcium supplements is extracted from rocks or produced synthetically and not directly from shellfish or eggshells, most would consider it to be vegan. However, calcium carbonate in rocks comes from the sedimentation of coral and the shells of small invertebrate animals like shellfish and snails (1).

Therefore, opinions may differ on whether calcium carbonate can be considered vegan. Personally, I would argue that it is acceptable for vegans to consume calcium carbonate.

A primary ethical reason for people to choose veganism is to support the humane treatment of animals and to avoid purchasing products that cruelly exploit animals for the benefit of human beings.

Since calcium carbonate derived from limestone and other rocks does not exploit or harm animals, I believe vegans can consume it without compromising their morals. However, considerations like these are always up to the individual to decide.

What products contain calcium carbonate?

Calcium carbonate can be found in:

  • Calcium supplements. These are often used by people who are unable to get enough calcium in their diet or who have osteoporosis.
  • Antacids. Calcium carbonate is an antacid, meaning it helps symptoms of heartburn by neutralizing stomach acid (6). TUMS is a brand of antacids known to contain calcium carbonate.
  • Phosphate binders. These are taken by people on hemodialysis to help reduce the amount of phosphorus they absorb from food. Calcium carbonate attaches to phosphorus in the small intestine, preventing some of it from being absorbed into the bloodstream. 
  • Toothpaste. Calcium carbonate is sometimes added to toothpastes to help prevent dental cavities and provide light abrasion, helping to clean teeth (7).
  • Green leafy vegetables. Dark green vegetables like broccoli and kale naturally contain calcium carbonate.
  • Fortified non-dairy milk. Some non-dairy milks such as soy or almond may be fortified with calcium carbonate in order to increase their calcium content, making them similar to dairy products in terms of calcium. If used, calcium carbonate will be listed in the ingredients list on the nutrition label.
Photo of the nutrition facts label and ingredients on a soy milk carton

How to tell if calcium carbonate is vegan

While most calcium carbonate used in the products listed above is likely sourced from rocks or produced synthetically, there is a chance it could be sourced from shellfish or eggshells instead. 

Some calcium carbonate supplements do list eggshell on the label, and indicate that the product contains eggs. One product that provides this information is the Swanson Eggshell Calcium with Vitamin D-3, which makes sense because this product is specifically marketed as being sourced from eggshells.

Product labels may or may not provide this information, unless the product has a certified vegan label. Most calcium carbonate supplements are likely not made using eggshells since egg allergies are quite common.

If you’re not sure, it’s best to contact the product manufacturer. They should be able to tell you if the product is vegan.

Should vegans take calcium carbonate supplements?

Calcium is an essential nutrient for maintaining strong bones and teeth and for proper nerve and muscle function. According to the National Institutes of Health, most adults need 1000 mg of calcium every day. For women over age 50 and men over age 70, this increases to 1200 mg (8).

It’s common for vegans to wonder whether they need to take a calcium supplement. According to the Academy of Nutrition and Dietetics, vegans can meet their calcium needs through food by consistently including calcium-rich plant-based foods in their diets (9).

In general, there is no benefit from taking dietary supplements when you already get enough of a nutrient from food. Calcium supplements are not recommended for individuals who get enough calcium through their diet. 

When dietary intake of calcium is low, it is often best to try and eat more calcium-rich foods before considering supplementation since these foods also provide other important nutrients.

So what’s the harm in taking a supplement? Wouldn’t more calcium be a good thing? While taking a calcium supplement might seem like a no-brainer to avoid deficiency, scientific research suggests this may be risky. 

The risk of taking a calcium supplement when already getting enough calcium from food is that too much calcium will build up in the bloodstream (10).

It is always best to talk with a physician prior to taking a calcium supplement. Some potential negative consequences of taking calcium supplements (as opposed to calcium from food) include:

  • Increased risk of cardiovascular diseases. Although rare, research has found an increased risk of heart attack and other cardiovascular diseases when people take 1000 mg or more of calcium as supplements per day. This may happen as a result of high levels of calcium in the bloodstream building up in the heart and arteries (11).
  • Unclear benefits for osteoporosis. While there is a lot of research showing calcium supplementation is helpful for preventing osteoporosis, some studies have actually shown an increased risk of osteoporosis when taking a calcium supplement. There is enough conflicting evidence that the best use of calcium supplements for osteoporosis is unclear.
  • Unpleasant gastrointestinal side effects. Calcium supplements, and calcium carbonate supplements in particular, have been associated with increased constipation, gas, and bloating.
  • Increased risk of kidney stones. Supplementing with about 1000 mg of calcium has been associated with an increased risk of developing kidney stones.
  • Increased risk of fatal prostate cancer. Research has found that taking calcium supplements may increase the risk of dying from prostate cancer, although more research is needed as this finding was only based on two studies (12).

The amount of calcium in the body and how the body uses that calcium are affected by a number of things, including but not limited to a person’s age, gender, dietary calcium intake, supplemental calcium intake, and Vitamin D status (13).

If taking a vegan calcium supplement, it is best to take no more than a 500 mg calcium dose at one time. The body does not absorb calcium as well over a 500 mg dose (13).

Vegan sources of calcium from food

There are a variety of plant-based foods that have calcium, including soy-based foods, beans, legumes, nuts, seeds, and some green leafy vegetables. If you follow a vegan diet, try to eat foods from this list every day:

  • Tofu ( ¼ of a block, prepared with calcium sulfate or other calcium salt) – 553 mg
  • Soy milk or other non-dairy milk (1 cup, calcium-fortified) – 300 mg
  • Collard greens (1 cup, cooked) – 268 mg
  • Blackstrap molasses (1 Tbsp) – 200 mg
  • Turnip greens (1 cup, cooked) – 197 mg
  • White beans (1 cup) – 191 mg
  • Tempeh (1 cup) – 184 mg
  • Mustard greens (1 cup, cooked) – 165 mg
  • Tahini (2 Tbsp) – 130 mg
  • Teff (1 cup) – 123 mg
  • Amaranth (1 cup) – 116 mg
  • Almond butter (2 Tbsp) – 111 mg
  • Chickpeas (1 cup) – 104 mg
  • Edamame (1 cup) – 98 mg
  • Bok choy (1 cup, raw) – 76 mg
  • Chia seeds (1 Tbsp) – 76 mg
  • Broccoli (1 cup, cooked) – 76 mg
  • Almonds (1 ounce) – 76 mg
  • Kale (1 cup, cooked) – 74 mg
  • Chinese cabbage (pak choi) (1 cup, shredded) – 74 mg
  • Brussels sprouts (1 cup, cooked) – 68 mg
  • Okra (8 pods, cooked) – 65 mg
  • Dried figs (¼ cup) – 60 mg
  • Pinto beans (½ cup) – 54 mg
  • Corn tortilla (6 inch) – 46 mg
  • Lentils (1 cup) – 38 mg
  • Flax seeds (2 Tbsp, ground) – 36 mg
  • Hemp seeds (3 Tbsp) – 21 mg

All nutrition information is obtained from the USDA FoodData Central database.

Other leafy green vegetables including spinach, beet greens, and swiss chard are also high in calcium. However, these leafy greens also contain high amounts of oxalates, which are naturally occurring compounds that block much of the calcium from being absorbed by the body. Because of this, it’s better to get calcium from the foods in the bulleted list above.


In summary, calcium carbonate is most often sourced from rocks like limestone and marble, and therefore foods and supplements containing calcium carbonate are most likely vegan unless labeled otherwise.

However, since calcium carbonate can also be sourced from shellfish or chicken eggshells, it is best to check with the manufacturer just to be sure.

Most vegans can get enough calcium by consistently eating plant-based foods that are rich in calcium. Taking calcium supplements may lead to some negative health effects, although the research is not always clear.

If you need help making sure you’re getting enough calcium on a vegan diet, a vegan dietitian can help. 

*RD note* – Unsure how to prepare calcium-rich tofu, or wondering if there’s any way to make it taste… not bland? Read my post entitled What Does Tofu Taste Like? [The Ultimate Flavor Guide].

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