Why is calcium important?

Calcium is an essential mineral for the human body. Many Greeks do not consume the necessary amount of calcium on a daily basis. Ninety-nine percent of the body’s calcium is found in our bones and teeth. It is an essential building material for developing strong, dense bones when we are young, and for maintaining our bones in the best possible condition as we age, so as to avoid unpleasant consequences.

And that is not all. Calcium also plays a role in a number of important bodily functions, such as blood clotting, muscle contraction, and transmission of nerve impulses.

Every day you lose significant amounts of calcium, mainly through urine, stool, and sweat. Calcium is also continuously lost as a component of your nails and hair.

Since, unfortunately, your body cannot produce calcium, yet loses it daily, and since it is involved in so many bodily functions, it becomes clear that adequate calcium intake through the daily diet is absolutely essential.

If this does not happen, the body will draw calcium from its largest reserves, namely the bones, gradually causing them to thin.

Reading food labels

How can you know whether you are getting enough calcium on a daily basis?

The recommended daily calcium intake for adults is around 1000 mg (milligrams). Labels on packaged foods can provide a great deal of useful information. They usually indicate the amount of calcium contained in one serving of the product, or alternatively per 100 grams of the product. In addition, they may also indicate the percentage (%) of calcium content based on the recommended daily intake.

For example, a product label may state 20 mg of calcium (internationally indicated as “Ca+”) per serving, or 8 mg of calcium per 100 grams of product, or it may also include the indication 10% of the RDI (Recommended Daily Intake).

In addition to foods that are considered principal sources of calcium, namely dairy products, calcium is also obtained from other sources (e.g. fruits, vegetables, nuts, and others). The total amount from these sources usually does not exceed 250 mg daily, that is, one quarter of the RDI; nevertheless, it should be taken into account when calculating the total daily calcium intake from food.

Sources of calcium

As is well known, dairy products contain large amounts of calcium. Milk, yogurt, and cheese contain high levels, and in general their daily consumption ensures an adequate calcium supply for the body. Certain green vegetables and fruits contain smaller amounts. People with high cholesterol levels are advised to consume more vegetables and low-fat dairy products. Also, individuals with gluten intolerance, who experience significant digestive discomfort with dairy products, should not be discouraged from consuming them. They should look for suitable products—that is, gluten-free products—or use tablets containing artificial lactase enzyme.

There are also many products on the market that are fortified with calcium, meaning that they contain artificially increased amounts of calcium beyond what is naturally present in the food. These products are intended for people who, for various reasons, cannot obtain at least 1000 mg of calcium through their daily diet. Such products include milk, soy milk, juices, cereals, bread, some snacks, and even bottled water. If you consume some of these products, be particularly careful to shake well those that are in liquid form, because calcium tends to settle.

Recommended Daily Intake (RDI) of Calcium

According to international scientific guidelines:

• Adults under 50 years of age need 1000 mg (that is, 1 gram) of calcium and 400–800 IU (International Units) of vitamin D daily.
• Adults over 50 years of age need 1200 mg of calcium and 1000 IU of vitamin D daily.

These amounts include calcium obtained both from food and from dietary supplements.

People who obtain the necessary amount of calcium from their diet do not need supplements. Some individuals, however, may require such preparations for various reasons, as well as vitamin D supplements.

In general, there are two types of vitamin D supplements: vitamin D2, also called ergocalciferol, and vitamin D3, also known as cholecalciferol. Older studies suggested that D3 was a better option than D2, but more recent research has shown that there is no substantial difference.

Excessive calcium intake is not without consequences. In predisposed individuals, it may lead to the formation of kidney stones and painful renal colic, as well as other health problems. According to experts, the upper safe limit of daily calcium intake ranges, depending on the individual, from 2000 to 2500 mg (2–2.5 grams).

Calcium supplements

The use and dosage of calcium supplements depend on the amount of calcium you obtain from food. People who get enough calcium through their diet do not need dietary supplements. Taking more calcium than you need provides no additional benefit. On the contrary, excessive intake of calcium supplements may cause problems such as kidney stones and constipation.

Calcium in its natural form does not exist as a free element, but only in complex compounds (salts), that is, combined with other substances. The main such compounds are calcium citrate, calcium carbonate, calcium phosphate, and calcium gluconate. These calcium compounds contain different percentages of elemental calcium, which is the actual amount of calcium provided.

Pay particular attention to the labels of calcium supplement products in order to calculate the amount of elemental calcium they contain and how much of it you will get from one, two, or more tablets. The serving amount or even the recommended dosage by age may also be indicated.

The amount of calcium supplement a person ultimately needs depends on the individual’s requirements, cost, availability, and ease of use. Calcium supplements do not require a medical prescription in order to be purchased from pharmacies. By contrast, some preparations fall into the category of medicines and do require a prescription. In any case, it is advisable to consult your doctor or dietitian for appropriate guidance and advice.

A simple way to add calcium to your diet

One tablespoon of low-fat powdered milk contains approximately 50 mg of calcium. Add a few spoonfuls, according to your preference, to:

• Desserts and ice cream
• Biscuits
• Bread
• Soups
• Cakes and pastries
• Sauces

Other minerals and vitamins

Calcium is often included in dietary supplements together with other vitamins and salts. Vitamin D is essential for the proper absorption and use of calcium by the body, but it is not always necessary to take it simultaneously (at the same moment) with calcium.

Minerals such as magnesium and phosphorus, and vitamins such as vitamin K, are also essential for bone health. These substances are more easily obtained through a balanced daily diet, and experts recommend multivitamin preparations only when there are strong indications of deficiency due to an unbalanced diet.

Safety

Most dietary supplements are made from shellfish shells, ground animal bones, and dolomite (a calcium-magnesium carbonate salt). They may contain lead or other toxic metals. You should always choose dietary supplements that have been approved by Greek, European, or international authorities (e.g. EOF, FDA) for greater reliability.

You should discuss with your doctor or pharmacist any possible interactions between dietary supplements and medications you are already taking. Some examples are listed below and highlight the seriousness of the matter:

• Absorption of the antibiotic tetracycline is impaired by simultaneous administration of calcium supplements.
• Calcium supplements should not be taken at the same time as iron supplements.
• Thyroid hormones should be taken at least 4 hours before (or after) calcium supplements in order to be properly absorbed.
• Medicines that generally need to be taken on an empty stomach should not be taken at the same time as calcium supplements.
• If you are taking proton pump inhibitors (PPIs) because of a stomach problem, prefer supplements containing calcium citrate, which can be absorbed without the presence of gastric acid. Most calcium salts require an acidic environment for absorption.

Absorption of calcium by the body

Calcium is found in foods and dietary supplements in the form of salts. In order for these salts to dissolve and calcium to be absorbed, an acidic environment is required. This environment is provided in the stomach by gastric fluids. Chewable or liquid dietary supplements are generally absorbed more easily, because their salts dissolve before they reach the stomach. They may have an unusual taste, but these dosage forms do serve a purpose.

Calcium is best absorbed when taken in amounts of up to 500–600 mg at a time, whether from food or supplements. Larger amounts may be lost during digestion. For this reason, it is better to spread the calcium you take daily across meals. An average diet will provide you with 500–600 mg of calcium, so another 600 mg may be taken in supplement form.

Calcium supplements (or medicinal products containing calcium) should therefore be taken in divided doses of approximately 300–500 mg daily with meals, for better absorption in the acidic environment of the stomach. An exception is calcium citrate salts, which do not require an acidic environment in order to be properly absorbed by the body.

Undesirable effects (“side effects”)

A common side effect of calcium supplements is gastrointestinal disturbance, especially gas and tenesmus (the urge to defecate), as well as constipation. Drinking more fluids will most likely not improve the situation. It is preferable to try another dietary supplement (or another medicinal preparation).

Another good way to improve tolerance to side effects is to increase the supplement dose gradually, starting with low divided doses throughout the day. The dose may even be increased over the course of a week, until the desired levels are reached.