Calcium – why is it so important for our body?
Calcium is one of the key macronutrients that Poles still consume too little of. According to the Institute of Food and Nutrition, the average calcium intake among Poles is far too low, at around 600 mg/day, or only about 60% of the recommended intake.
Calcium is a very important mineral for the body, which needs to be supplied with food. It is most often associated with bone structure, but this is not its only role. Here are some important functions that calcium performs in the body:
- It is the building block of bones and teeth. The body converts calcium into bone tissue. To keep this tissue healthy and strong, it is necessary, among other things, to use a diet sufficiently rich in calcium.
- It builds nails, hair and blood vessels. Although these structures are rarely associated with calcium, the element takes an active role in their formation and maintenance.
- It ensures proper functioning of the nervous system. Calcium is involved in conducting nerve impulses, which enable the exchange of information in the body.
- It allows muscles to contract properly – both skeletal muscles, used for movement, and smooth muscles, responsible for the work of internal organs. Calcium deficiency can lead to disorders in this area.
- It ensures proper heart function. The heart is the most important muscle in the body, whose work is also closely dependent on levels of calcium (and of other electrolytes).
- It regulates blood pressure and maintains normal contractility of blood vessels.
- It takes an active part in the process of blood clotting, as well as cell regeneration.
- It affects hormonal regulation. It is related to parathyroid hormone, vitamin D and hormones that regulate kidney function.
We debunk the myth that “calcium is only important for bone health”. In fact, calcium is one of the key ions with multiple functions in the body. Its role goes far beyond supporting skeletal health.
Adequate calcium intake is important at every stage of life because of its broad physiological functions. However, it is particularly important to regularly supply adequate amounts of calcium during childhood, when bone tissue develops most rapidly. Calcium supply in post-menopausal women is no less important, as hormonal changes predispose to bone weakness.
We also debunk the myth that “calcium is only important for children”. Although in childhood calcium is indeed crucial for building a durable skeleton for years to come, in adulthood a proper supply of this macronutrient is also essential. A diet rich in calcium helps maintain physical fitness, dental health, proper heart function and, according to some studies, can support the fight against certain types of cancer.
The consequences of calcium deficiency in the body can include rickets (in children), osteoporosis and osteomalacia (in adults), tetany, increased excitability of the body, arrhythmia and electrolyte disturbances, increased blood pressure and neurological disorders.
Excess calcium is relatively rare and is unlikely to occur with a typical diet (even one very rich in this mineral!). The body naturally regulates its absorption, and with high supply it simply reduces it. Excessive levels of calcium in the body can occur, of course, but they are usually the result of improper supplementation or disease, not excessive supply from the diet.
An interesting fact: Bones are a kind of storehouse of calcium in the body. With low levels of calcium in the blood and cell fluids, the body can “release” calcium from the bones. However, this is not a beneficial process, as it contributes to the decalcification of bone tissue.
Dietary calcium requirements
Dietary calcium requirements depend primarily on age and gender. According to the 2020 standards for the Polish population, the diet of every Pole should include the following calcium intake:
| Group | Daily calcium requirement [RDA] |
| Infants (0-6 months) | 200 mg |
| Infants (7-11 months) | 260 mg |
| Children (1-3 years old) | 700 mg |
| Children (4-9 years old) | 1,000 mg |
| Boys and girls (10-18 years old) | 1,300 mg |
| Men (19-65 years old) | 1,000 mg |
| Men >65 years old | 1,200 mg |
| Women (19-65 years old) | 1,000 mg |
| Women >65 years old | 1,200 mg |
| Pregnant and breast-feeding women <19 years old | 1,300 mg |
| Pregnant and breast-feeding women >19 years old | 1,000 mg |
Dietary sources of calcium – not just dairy!
We debunk the myth that “the best source of calcium is milk”. Indeed, milk contains a lot of calcium, but many products have even more. The top ones, for example, include hard cheese or small fish eaten with the bones.
Here’s a list of the best animal sources of calcium:
- Parmesan – 1,184 mg of calcium/100 g
- Milk powder – 1,062 mg of calcium/100 g
- Sprats – 1,000 mg of calcium/100 g
- Cheddar cheese – 721 mg of calcium/100 g
- Gouda cheese – 700 mg of calcium/100 g
- Bryndza cheese – 630 mg of calcium/100 g
- Camembert cheese – 510 mg of calcium/100 g
- Sardines – 381 mg of calcium/100 g
- Concentrated, unsweetened milk – 258 mg of calcium/100 g
- Natural yoghurt – 170 mg of calcium/100 g
- Milk – 125 mg of calcium/100 g
- Sea bass – 120 mg of calcium/100 g
- Lean cottage cheese – 98 mg of calcium/100 g
- Shrimps – 70 mg of calcium/100 g
- Herring – 60 mg of calcium/100 g
- Egg – 55 mg of calcium/100 g
- Whey – 47 mg of calcium/100 g
We also debunk the myth that “you can only get calcium from milk and dairy products”. The fact is that there are many plant products very rich in calcium. Often, this calcium is less well absorbed than from dairy products, but with proper intake, it can meet the needs of the body at any stage of life.
Here are some of the best plant sources of calcium:
- Sesame – 1,474 mg of calcium/100 g
- Sunflower seeds – 367 mg of calcium/100 g
- Tofu – 350 mg of calcium/100 g
- Soybeans – 348 mg of calcium/100 g
- Almonds – 273 mg of calcium/100 g
- Parsley – 245 mg of calcium/100 g
- Dill – 223 mg of calcium/100 g
- Halva – 211 mg of calcium/100 g
- Chickpeas – 193 mg of calcium/100 g
- Hazelnuts – 188 mg of calcium/100 g
- Garlic – 180 mg of calcium/100 g
- Basil – 177 mg of calcium/100 g
- Kale – 157 mg of calcium/100 g
- Wheat bran – 150 mg of calcium/100 g
- Beans – 150 mg of calcium/100 g
- Oat grain – 117 mg of calcium/100 g
- Tempeh – 111 mg of calcium/100 g
- Spinach – 106 mg of calcium/100 g
- Onions – 100 mg of calcium/100 g
- Barley – 93 mg of calcium/100 g
- Peas – 89 mg of calcium/100 g
We debunk the myth that “sesame is 10 times better source of calcium than milk”. It is true that sesame is more than 10 times more abundant in calcium than milk. However, this does not mean that it is 10 times better source of this mineral. The bioavailability of calcium from sesame is lower due to its high content of phytic acid and other anti-nutrients that reduce its absorption. Sesame (and other plant products) can therefore be a source of calcium, but its utilisation in the body cannot be compared one-for-one with dairy products.
Factors affecting calcium utilisation in the body
The absorption of calcium from food is about 10-40%, depending on its source and other components of the meal. This means, roughly speaking, that in practice it is not enough to eat adequate amounts of calcium to absorb it well. There are ingredients that limit the absorption of calcium, as well as those that facilitate its utilisation in the body. Pay attention to them if you want to get the most out of this mineral in your meals.
Factors limiting calcium absorption and utilisation:
- Phytic acid, which is mainly found in various cereals and seeds. When combined with calcium (but also with other minerals, such as iron and magnesium), it forms insoluble and difficult-to-absorb compounds. Therefore, the presence of phytic acid in a meal reduces the body’s ability to utilise the calcium consumed.
- Oxalic acid, present in many vegetables, such as spinach, rhubarb and kale. It forms insoluble compounds called oxalates with calcium, which are difficult for the body to absorb. Oxalates are not absorbed and soluble in the intestines, which means that the calcium consumed is also absorbed to a limited degree.
We debunk the myth that “you shouldn’t combine spinach with dairy”. The fact is that with the combination of oxalic acid-rich spinach and dairy (such as cream or cheese), which provide calcium, its absorption will be partially reduced. With this combination, however, no toxic substances that should be avoided are formed. The absorption of calcium from cheese eaten unaccompanied by spinach will be greater than if eaten in one meal with spinach, but this relationship is so insignificant that it should not be decisive in choosing a meal.
- Insoluble fibre. Its high content in a meal can speed up intestinal transit and indirectly limit calcium absorption. However, this is a relatively small impact.
- Lots of fat in the diet. The high fat content in the diet can affect the intestinal mucosa and cause the formation of compounds with calcium that partially limit its absorption.
- High phosphorus content in the diet. Calcium and phosphorus are so-called antagonists. Both minerals play a key role in building bones, but the ideal ratio between calcium and phosphorus in the diet is about 2:1 in favour of calcium. In practice, in the Western diet, there is much more phosphorus than calcium. This causes adverse changes in the body’s calcium metabolism. When the calcium/phosphorus ratio is disturbed, calcium can be “leached out” from the bones. Excess phosphorus also reduces calcium absorption in the intestines.
- The content of other minerals in the meal (e.g. magnesium, zinc). Minerals can “compete” with each other for absorption in the gut.
Factors that increase calcium absorption:
- Lactose. It lowers the pH in the intestines (especially in the colon) and increases the solubility of calcium and its compounds. However, this effect is observed only in people who tolerate lactose well. In people with lactose intolerance, the effect can be just the opposite.
- Some amino acids (lysine, arginine). They increase the solubility of calcium salts and support its transport across the intestinal membrane. Lysine can increase calcium absorption by up to 80%!
- SCFAs (short-chain fatty acids). Produced by the gut microbiome, SCFAs lower the pH in the intestines and improve the ability of calcium to dissolve and absorb. SCFAs also stimulate calcium ion exchange in intestinal cells.
- Inulin and other oligosaccharides. They increase calcium absorption, mainly in the large intestine by lowering the pH of the environment. In addition, they provide food for intestinal bacteria that secrete SCFAs, which facilitate calcium absorption.
- Vitamin D. It increases calcium absorption in the intestines through activation of calcium-binding proteins, which enables its transport into the blood. Vitamin D deficiency reduces the efficiency of calcium absorption by up to 50%!
- Milk phosphopeptides. They increase the absorption of calcium consumed, making dairy products actually a good source of calcium.
As you can see, many of the factors that facilitate calcium absorption are ingredients found in milk and dairy products. Dairy products are recommended for children and people who need to increase the supply of calcium in the diet not only because of the calcium content itself, but also because of the additional elements (lactose, amino acids, phosphopeptides) that create a friendly environment for absorbing the calcium consumed. Of course, it is also possible to ensure a healthy, balanced and calcium-rich dairy-free diet. However, if you consume dairy and feel good after it, it is one of the cheapest and best available sources of calcium.
How to eat more calcium? Practical tips from a dietitian
Here are some tips to increase your calcium supply in the diet.
- Sprinkle your dishes with Parmesan or other hard cheese. A spoonful of Parmesan cheese as a sprinkle on a salad, soup or dinner is not that many calories, but a powerful dose of calcium (about 100 mg).
- Choose high-mineralised water rich in calcium. By drinking 1.5 litres of water a day, you can take in up to 300 mg of valuable calcium. High-mineralised water is not for everyone, but if you have no contraindications, you can drink it confidently.
- Do not avoid small fish, eaten with skeletons. The high calcium content of sprats or sardines is due to the fact that they are eaten with skeletons. It is this element that is the real calcium superfood – so don’t give up eating it and eat small fish whole.
- Use greens. Green leafy vegetables contain a lot of calcium. Dill, coriander, basil, parsley... Use leafy greens in all your meals.
- Sprinkle salads, soups, sandwiches and smoothies with calcium-rich grains: sesame, chia, almonds. Each pinch is an extra dose of this mineral.
- If you don’t drink milk, opt for calcium-fortified plant drinks. Not every plant-based drink is enriched with it, but you can easily find such products on the market. Naturally, plant-based drinks have little calcium (e.g. a soy beverage is 30 mg/100 ml), but after fortification, they sometimes outperform even classic dairy.
- Don’t give up cheese. Many people who are “on a diet” give up eating cheese altogether because of its high calorie content. Sometimes this can be a good tactic, but unless you have contraindications or follow a very restrictive diet, 1-2 slices of cheese a day is a balanced serving and a valuable dose of calcium.
We debunk the myth that “more calcium in the diet means stronger bones”. While proper supply of calcium plays a huge role in building strong bone tissue, that’s not all. Other minerals, vitamin D, properly functioning hormones, and even... adequate supply of protein are also needed for bone health. Not every abnormality in bone tissue quality is a direct result of a calcium-poor diet.
References:
- Dolińska B., Mikulska A., Ryszka F., Factors enhancing calcium's absorption, Annales Academiae Medicae Silesiensis, 2009;63(1):76-83.
- Jarosz M., Rychlik E., Stoś K., Charzewska J. (red.), Normy żywienia człowieka dla populacji Polski i ich zastosowanie, Narodowy Instytut Zdrowia Publicznego – Państwowy Zakład Higieny, 2020.