Getting enough dietary calcium is easy for most people.
However, others do not meet their daily requirements because of restrictive diets, low food intake or food shortage. For these people, cheap sources of calcium like eggshells may prove useful.
Not to mention, using eggshells is an excellent way to reduce your kitchen waste, even by just a little bit.
This article takes a look at the risks and benefits of eggshell supplements.
An eggshell is the hard, outer covering of an egg. It consists mostly of calcium carbonate, a common form of calcium. The rest is made up of protein and other minerals ().
Calcium is an essential mineral that is abundant in many foods, including dairy products. Lower amounts are also found in many leafy and root vegetables.
In the past decades, eggshell powder processed from hen eggs has been used as a natural calcium supplement. Eggshells are roughly 40% calcium, with each gram providing 381–401 mg (, ).
Half an eggshell may provide enough calcium to meet the daily requirements for adults, which is 1,000 mg per day (, ).
Summary Eggshells are commonly used as a calcium supplement. Just half an eggshell may provide enough calcium to meet the average daily requirements of an adult.
Eggshells consist of calcium carbonate, along with small amounts of protein and other organic compounds.
Calcium carbonate is the most common form of calcium in nature, making up seashells, coral reefs and limestone. It is also the cheapest and most widely available form of calcium in supplements.
Studies in rats and piglets confirm that eggshells are a rich calcium source. Moreover, they are absorbed as effectively as pure calcium carbonate (, , 6).
Some even suggest its absorption is better than that of purified calcium carbonate supplements.
A study in isolated cells found that calcium absorption was up to 64% greater from eggshell powder compared to pure calcium carbonate. Researchers attributed these effects to certain proteins found in eggshells ().
In addition to calcium and protein, eggshells also contain small amounts of other minerals, including strontium, fluoride, magnesium and selenium. Just like calcium, these minerals may play a role in bone health (, , , , ).
Summary Some evidence suggests that the calcium in eggshell powder may be better absorbed than pure calcium carbonate, making it an effective calcium supplement.
Osteoporosis is a health condition characterized by weak bones and an increased risk of bone fractures. In 2010, it affected an estimated 54 million older Americans ().
Old age is one of the strongest risk factors for osteoporosis, but inadequate calcium intake may also contribute to bone loss and osteoporosis over time.
If your diet is lacking calcium, taking supplements may help you reach your daily requirements. Eggshell powder is a cheap option.
One study in postmenopausal women with osteoporosis found that taking eggshell powder, along with vitamin D3 and magnesium, significantly strengthened their bones by improving bone mineral density ().
Eggshell powder may even be more effective at reducing osteoporosis risk than purified calcium carbonate.
A study in Dutch, postmenopausal women found that eggshell powder improved bone mineral density in the neck compared to a placebo. In contrast, purified calcium carbonate did not significantly improve it ().
Summary Taking eggshell powder may improve bone strength in people with osteoporosis. One study indicates that it may be more effective than purified calcium carbonate supplements.
The eggshell membrane is located between the eggshell and the egg white. It is easily visible when you peel a boiled egg.
While technically not part of the eggshell, it is usually attached to it. When making eggshell powder at home, there is no need for you to remove the membrane.
Eggshell membrane mainly consists of protein in the form of collagen. It also contains small amounts of chondroitin sulfate, glucosamine and other nutrients.
The trace amounts of these beneficial compounds in eggshell membrane are unlikely to have any significant effects on your health.
However, some studies show that regular intake of eggshell membrane supplements may benefit your joints. More studies are needed to confirm their potential effectiveness (, , , ).
Summary The eggshell membrane separates the eggshell from the egg white. Supplements made of eggshell membranes provide nutrients that may improve joint health.
When prepared correctly, eggshell powder is considered safe. There are just a few things you need to keep in mind.
First, do not attempt to swallow large fragments of eggshell as they might injure your throat and esophagus. The next chapter gives you a few tips on how to grind eggshells into powder.
Second, eggshells may be contaminated with bacteria, such as Salmonella enteritidis. To avoid the risk of food poisoning, make sure to boil eggs before eating their shell (, ).
Finally, natural calcium supplements may contain relatively high amounts of toxic metals, including lead, aluminum, cadmium and mercury ().
However, the amounts of these toxic elements in eggshells tend to be lower than in other natural calcium sources, such as oyster shells, and is generally not a concern (, ).
Summary To prevent the risk of injury or infection, eggshells should be boiled and ground into powder before you eat them.
You can either make your own eggshell supplements at home or buy pre-made eggshell powder in health food shops.
Eggshell powder can be made at home using a pestle and mortar. Others have reported using a rolling pin or a blender and a sieve to sift out larger particles.
Just be sure to grind the eggshells into powder or very small fragments before eating them.
If you plan to store the powder for later use, it is a good idea to dry the shells before crushing them.
You can then add the powder to food or mix it with water or juice. One study concluded that some of the best foods to add eggshell powder to are bread, spaghetti, pizza and breaded, fried meat ().
Roughly 2.5 grams of eggshells should be enough to meet the daily calcium requirements of an adult.
To be on the safe side, moderate your intake and do not take calcium supplements unless recommended by a health professional.
Some experts discourage the regular intake of calcium supplements and doubt their benefits for bone health.
They are also concerned that excessive intake of calcium may cause health problems, such as kidney stones, and potentially raise the risk of heart disease ().
Summary Eggshells can be ground into powder and then mixed with water or food. Daily intake of 2.5 grams should be enough to meet your requirements, though speak to your health professional.
Eggshells are not only one of the cheapest sources of calcium — they also appear to be among the most effective.
If you have a hard time meeting your calcium requirements or if you suffer from osteoporosis, homemade eggshell powder is an effective and inexpensive alternative to commercial supplements.
In fact, studies show that eggshell calcium is well absorbed and may strengthen the bones of people with osteoporosis.
Preparing eggshell powder at home is easy. After boiling and drying the shells, you can crush them with a pestle and mortar and mix the powder with water or add it to food.