Calcium - The mineral for the bones

What is calcium?

Calcium is a chemical element. It is marked with the element symbol Ca in the periodic table and is in the second main group. The shiny, silver-white metal is the fifth most common element in the earth's shell. It can be found in water, soil, rocks and in living beings.

However, calcium is only found in the environment in a bound form. The mineral substance is also present in bound form as calcium phosphate in the human body.

Calcium in the body

Depending on their size, weight and age, everyone has an average of 1 to 1.1 kg of calcium in their body. In contrast to iron and selenium, for example, the mineral is therefore not a trace element but a quantity element.

Around 90% of the calcium in the body is in bound form in the bone. 9% of the calcium storage is found in the teeth. The rest circulates in the blood and in the interstitial space or is needed directly in the cells. Here, for example, the mineral plays a role in the irritability of the cell and thus in the transmission of the nerve stimuli.

Calcium deficiency

Calcium is one of the nutrients whose requirements are often not met by food. That is why the mineral is classified as a risk nutrient by both the German and the Austrian Nutrition Report. According to the experts, there is an urgent need for action from a health policy perspective.

The results of the German National Consumption Study from 2012 confirm the deficiency situation. According to this, all population groups ingest too little calcium in their diet on average. Children, adolescents and seniors are particularly often affected by a calcium deficiency.

Calcium deficiency - The causes

There are many reasons for a calcium deficiency. Many people eat too little calcium-containing food. But hormonal disorders, stomach and intestinal complaints, increased calcium excretion or a vitamin D deficiency can also lead to a calcium deficiency.

Calcium deficiency due to improper nutrition

Milk and dairy products are considered to be rich in calcium. Depending on the mineral content, tap and mineral water can also contribute to the calcium supply. Calcium-rich vegetables include broccoli and fennel. Since calcium is so widespread, the need should easily be met?

However, calcium intake from food is affected by several factors. Plants in particular contain contaminants that can impair the calcium usability. These include phytate (phytic acid), which is contained in wheat or oxalate. For example, oxalate occurs in spinach or rhubarb.

Likewise, fiber as well as fat and phosphorus inhibit the absorption in the intestine. The preparation also has an influence on the calcium content of the dishes. Watering, boiling or blanching vegetables also reduces the calcium content.

Another substance that inhibits the absorption of calcium in the intestine is caffeine. Anyone who drinks 2 cups of coffee a day for life has a significantly increased risk of osteoporosis in old age.

The same goes for alcohol. On the one hand, alcohol inhibits the absorption of calcium in the intestine. On the other hand, with increased alcohol consumption, less vitamin D3 is converted into the active form in the liver. As a result, calcium absorption deteriorates further.

Milk as the best calcium supplier?

Men and women, with the exception of vegans, consume the greatest amount of calcium through milk and dairy products. However, it has become controversial whether milk and dairy products really have such a positive effect on bone health due to their high calcium content.

A study by the University of Harvard with more than 70,000 participants showed that an increased milk supply increased the risk of bone fracture among the study participants in the long term. In this study, an improvement in bone density could only be achieved with calcium from green vegetables. The researchers suspected that milk contributes to acidification of the body. The resulting acids must be neutralized with the calcium from the milk, so that ultimately more calcium is consumed than absorbed.

Calcium deficiency due to a lack of parathyroid hormone

The parathyroid hormone is formed in the parathyroid glands. These sit on the thyroid gland and are a significant part of the calcium balance regulation. When the calcium level in the blood drops, the parathyroid hormone from the parathyroid glands ensures that:

• Calcium is released from the bones
• More calcium from food is absorbed in the intestine
• The excretion of calcium in the urine is reduced

As a result, the calcium level rises again within a short time. If the parathyroid glands no longer function properly or stop working completely, problems will arise. The parathyroid glands can be damaged, for example, during thyroid surgery or can be damaged by radiation to the thyroid gland.

Other causes of hypoparathyreodisumus, that is, an underactive parathyroid gland with parathyroid hormone deficiency, are autoimmune diseases or iron storage disease. A subfunction can also be hereditary.

Calcium deficiency due to a vitamin D deficiency

A lack of vitamin D is one of the most common causes of calcium deficiency. Strictly speaking, vitamin D is not a vitamin, but a hormone. It is formed in the body using sunlight.

Ideally, 80% of the demand is met this way. The body receives the remaining 20% from food. But a large part of the population has too low a vitamin level in the blood.

Older people in particular are at risk of a vitamin D deficiency. In everyday life, most people spend too little time in the sun. Especially in the winter months, in the western latitudes, the sun exposure is not sufficient to produce enough vitamin D. To meet the needs of infants and young children, pediatricians generally recommend the intake of nutritional supplements.

Vitamin D controls the absorption and utilization of calcium to a significant degree. The vitamin form calcitriol activates certain membrane channels and transport proteins in the intestinal wall. This allows the intestinal cells to absorb more calcium from their diet.

A lack of vitamin D consequently leads to a reduced absorption capacity of calcium in the intestine. This means that a deficiency can arise even if there is sufficient food. Vitamin D is also involved in the formation of various proteins and hormones that control the utilization of calcium. Adequate calcium utilization is only possible if enough vitamin D is available.

Calcium deficiency due to a lack of magnesium

Just like vitamin D, the mineral magnesium also plays a role in the availability of calcium. The parathyroid hormone from the parathyroid gland ensures that the calcium from food can be properly used. The hormone can only take on this task if sufficient magnesium is available.

Indigestion and calcium deficiency

Calcium is mainly absorbed from food in the small intestine. If the intestine is not healthy, absorption disorders and a mineral deficiency can occur. The following diseases can worsen the absorption:

• Inflammatory bowel diseases such as Crohn's disease and ulcerative colitis
• Celiac disease (gluten intolerance)
• Lactose intolerance
• Small bowel overgrowth (SIBO)

Calcium deficiency due to kidney diseases

Calcium deficiency also arises with kidney failure (renal failure). The kidneys no longer work properly, which means that substances such as phosphate are left in the blood. The phosphate binds to the calcium. This creates a salt that accumulates in various organs in renal failure. The calcium level in the blood drops, a calcium deficiency develops.

Calcium deficiency due to an increased need

In certain life situations, the need for calcium is increased. Pregnant and breastfeeding women in particular use more calcium. These women should therefore pay more attention to an adequate calcium intake through food or nutritional supplements.

Calcium and menopause

Post-menopausal women also belong to the risk groups with an increased need. During menopause, the woman's hormonal balance completely changes. Estrogen levels decrease and, as a result, the calcium absorption in the intestine also decreases. Absorption from the bone, on the other hand, increases so that women lose around 3 to 5% of their bone mass in the first period of menopause. With menopause, the risk of osteoporosis increases massively. Calcium supplementation can reduce the risk of osteoporotic fractures.

Calcium deficiency - effects and symptoms

Calcium takes on various tasks in the body. The complaints that can occur with a deficiency are correspondingly diverse. Symptoms of a calcium deficiency include:

• Skin problems such as dry skin or eczema
• Abnormal sensations such as tingling on the skin
• Poor circulation and irregular heartbeat
• Hair loss
• Brittle fingernails
• Caries and periodontal diseases
• Indigestion
• Bone metabolism disorders
• Osteoporosis (bone loss)
• Muscle cramps and tremors

In the case of a chronic deficiency, the symptoms do not all occur together. Often, people affected first notice a tingling in the mouth, on the hands or on the feet. If the doctor examines the reflexes, then the reflexes are increased.

A particularly severe calcium deficiency manifests itself by a so-called tetany. The hands take a paw position. The feet point towards the floor while sitting. One speaks here of the pointed foot position.

Another typical sign of a calcium deficiency is the Chvostek sign. Tapping a nerve trunk that is near the earlobe contracts the facial muscles. However, a positive Chvostek sign is only found if there is a pronounced calcium deficiency, for example if the parathyroid glands are damaged.

Acute or chronic calcium deficiency

Basically, you can differentiate between an acute and a chronic course in the case of a nutrient deficiency. An acute calcium deficiency suddenly arises with severe symptoms within a short time.

With an acute calcium deficiency, a so-called acute hypocalcemia, the nervous system is hyperirritable. The main symptom is hypocalcemic tetany. This is a seizure with your consciousness preserved. An acute calcium deficiency usually arises from an acute parathyroid insufficiency, poisoning or inflammation of the pancreas (pancreatitis).

The chronic calcium deficiency, however, develops gradually over a longer period of time. The symptoms of this long-term deficiency include, for example, hair loss or brittle nails. This calcium deficiency arises, among other things, from a low-calcium diet/nutrition or absorption disorders in the intestine.

Calcium effect

Calcium is used for the stability of the bones and teeth. This is surely the best known effect of the quantity element. But the mineral has many other effects that are just as important.

Calcium and the skeleton

The human skeleton consists of approximately 212 different bones. These include, for example, the shoulder blade, the humerus and the skull. 10 to 15% of the body weight are made up of the bone mass.

The human skeleton protects the internal organs, provides approaches for muscles and tendons, gives the body stability and keeps it up. Strong and stable bones are the prerequisite for our ability to move.

The bones of the skeleton consist of inorganic and organic substances. Collagen is one of the organic substances. Calcium compounds, on the other hand, are the most important inorganic substances in the bone.

The calcium molecules are integrated into a network of collagen fibers. While the collagen makes the bones limber and flexible to a certain extent, the calcium building blocks provide the necessary strength and stability.

The calcium level in the blood must be within a defined range. Otherwise there is a risk of muscle and nerve disorders. In order to compensate for large fluctuations, the body uses the storages in the bones when there is a lack of calcium in the blood.

Calcium is increasingly released from the bone. As a result, the bone mass shrinks and the bones become porous and brittle. This bone loss with a lack of bone strength is also called osteoporosis.

Calcium and the growth of the bone structure

The mineral is particularly important in the bone building phase. The bone reaches the highest bone mass and the highest bone density before the age of 30. After that, the skeletal bones continuously lose bone mass.

A lack of calcium and vitamin D in childhood and adolescence can increase the risk of osteoporosis in old age. With the help of a targeted nutritional supplement, bone density and bone mass can be improved. This also reduces the risk of fatigue fractures.

Calcium in osteoporosis

According to the World Health Organization (WHO), osteoporosis is one of the 10 most common diseases worldwide. Especially women after menopause and people over the age of 70 are affected by bone loss. A large number of fractures of the femur and vertebrae are due to osteoporotic bone changes.

As a multifactorial disease, osteoporosis has several causes but a calcium deficiency is one of the main factors for a lack of bone stability. Adequate calcium intake can reduce the likelihood of fractures in existing osteoporosis. Calcium replacement in combination with vitamin D also has a positive effect on bone health in postmenopausal women.

Calcium against periodontosis

When you think of osteoporosis, you first think of the large bones, such as the thigh bone or the vertebral bodies. The breakdown of the bone substance also affects the jaw bones, among other things. The loss of bone mass in the jaw is closely related to the periodontitis illness and also to premature tooth loss. ⁠

A decrease in bone mass in the skeletal bones is often also reflected in a reduction in the ability to keep your teeth. A targeted supply of bone-relevant nutrients such as vitamin D and calcium can strengthen the tooth support system and thus prevent tooth loss due to osteoporosis. Studies show that menopausal women who do not supplement calcium are at more than 50% higher risk of suffering from a periodontal tooth disease.

Calcium for muscles and nerves

Calcium does not only play a role in bone health. Nerves and muscles also depend on an adequate calcium level for their function. Outside the bone, calcium is particularly important as an electrolyte.

The mineral is a significant part of muscle contractions, e.g. active muscle shortening. The contraction of the muscle is triggered by the release of calcium from the so-called sarcoplasmic reticulum in the muscle cells.

Calcium and the stimuli transmission

The development of an action potential and thus the irritability of the nerve cells is also affected by the calcium content in the blood. The action potential is a brief change in the membrane potential of irritable cells. It serves to guide the stimulus conduction within the nervous system.

The stimulus conduction in the nervous system is quite complex. In order for different tissues and organs to work well together, fast communication is also required over long distances. Such rapid cell communication is guaranteed by the transmission of electrochemical signals.

There are different concentrations of charged ions inside and outside the cell. These maintain the so-called resting potential. When a stimulus hits the nerve cell, its sodium channels open. The sodium ions flow into the cell, so that the resting potential changes into an action potential.

Then the potassium channels are opened. Potassium flows out of the cell and the membrane potential changes towards resting potential. In this way, stimuli can be passed on via the nervous system.

The calcium decrease in the body leads to an altered charge on the outside of the cells. This changes the sodium channels and more sodium flows into the cells more quickly. Muscle and nerve cells can be irritated much faster as a result, the tendency to cramp increases accordingly.

Calcium in synapses

Via the so-called synapses, the nerve cells are in contact with each other and with other cells such as sensory cells, muscle cells or glandular cells.

In the case of a chemical synapse, the incoming action potential is converted into a chemical signal. To do this, the sending cell releases messenger substances (neurotransmitters), which overcome a small gap and then reach the other side of the synapse. Here the receiving cell converts the chemical neurotransmitter signal back into an electrical signal.

The body needs calcium so that this complicated process can run quickly and smoothly. When the action potential hits the synapse cell, calcium channels open. Calcium flows into the cell and releases the messenger substance there. If there is a lack of calcium, the synapse will no longer function properly.

In summary: Neither the nervous system nor the muscles can function without a sufficient amount of calcium. Calcium levels that are too high can also cause problems. A balanced calcium/magnesium ratio is crucial, since magnesium acts as an opponent of calcium in many processes.

Calcium and the acid-base household

The acid-base household is used to maintain a constant pH level in the blood and tissues. The pH in the blood should always be between 7.35 and 7.45. An overacidification is referred to as acidosis; an excessively high pH level is referred to as alkalosis.

Various buffer systems are available to the body to neutralize metabolic acids or added acids. However, if these buffer systems are overloaded, the acidic end products of the metabolism are bound in the inter-cell spaces and thus buffered.

While conventional medicine only knows about manifest acidosis with a visible acidification of the blood, alternative medicine often speaks of latent acidosis. This can be caused, for example, by an acidic metabolic state, the increased supply of acid-forming substances via food or shallow breathing.

With latent acidosis, minerals are released from the tissues to maintain the important blood pH level. In addition to magnesium, the body also uses calcium from the bones and other body structures. Therefore, latent metabolic acidosis can become noticeable through the demineralization of nails, hair and teeth. The hair falls out and becomes brittle and the fingernails break off faster. In the further course, acidosis also affects bone health and has a negative effect on the function of muscles and nerves.

People who suffer from the symptoms of overacidification can provide the body with buffers through the supply of minerals such as magnesium and calcium, for example from the Sango coral. This leaves the bones and teeth unaffected. Of course, it is also important to reduce the acid load so that buffers are no longer necessary. The following symptoms can indicate latent acidosis:

• Tiredness and fatigue
• Underperformance and difficulty concentrating
• Muscle cramps
• Brittle nails
• Hair loss
• Irregular heartbeat

Calcium in food

The most important calcium suppliers include milk and dairy products, calcium-rich mineral water and green vegetables. Berry fruits and nuts also contain calcium. A balanced natural food with a colorful selection of different foods is the basis of a good calcium supply.

Calcium in fruit

When people think of calcium, most people think of milk, yogurt or cheese first. Fruit is often not known to be a calcium-rich food. But there are different types of fruit that contain a relatively high amount of calcium.

Fruit rich in calcium (content in mg per 100g):

• Orange 161
• Tangerine 37
• Figs 35
• Kiwi 34
• Currants 29
• Grapefruit 22
• Blueberries 19th
• Grapes 14
• Mango 11
• Apple 5

Calcium in vegetables

Vegetables are an important source of calcium. However, not all vegetables contain large amounts of calcium. Green vegetables are particularly rich in calcium. The general rule is that the leaves of a vegetable plant have the highest calcium content. The stalks and stems follow, then the roots. The seeds, on the other hand, have the lowest mineral content.

Calcium-rich vegetables (in mg per 100g):

• Kale 254
• Green soybeans 197
• Garlic 181
• Broccoli 108
• Spinach 99
• Pak-Choi 93
• Cress 81
• Okra pods 81
• Endive salad 52
• Peas 43
• Brussels sprouts 42
• Butternut Squash 41
• Sweet potato 38
• Potatoes 34
• Romanesco 33

However, it should be noted that the calcium content refers to the raw food. Processing can significantly reduce the calcium content. In contrast to vitamins, minerals are heat stable. The high temperature during cooking doesn't harm the calcium content.

However, if too much water is used during cooking, minerals such as calcium are rinsed out and then poured away with the cooking water. The loss of nutrients is up to 20%. Cooking methods that use as little cooking water as possible should therefore be preferred. Vegetables containing calcium, for example, can be steamed well.

Calcium in milk and dairy products

Milk and dairy products such as yogurt or cheese are still considered to be the ultimate source of calcium. The calcium content in cow's milk is actually comparatively high at around 260 mg per 100 g. Depending on the variety, cheese and dairy products also contain quite a lot of calcium (in mg per 100g):

• Parmesan 853
• Provolone 756
• Cheddar 710
• Mozzarella 505
• Camembert 388
• Sheep milk 193
• Yogurt 183
• Cottage cheese 111
• Sour cream 101
• Cream 101

However, scientists disagree as to whether milk and dairy products are really good sources of calcium. While the German Society for Nutrition (DGE) still recommends the consumption of milk and dairy products, researchers at the Harvard University Public Health Graduate School recommend alternative plant-based calcium sources.

For example, the experts at the Harvard School of Public Health point out that milk contains a lot of calcium, but also a lot of saturated fatty acids. These are considered a risk factor for the development of cardiovascular diseases. In addition to this, the scientists lead studies in which a connection between milk consumption and prostate and ovarian cancer was found.

Calcium in nuts and seeds

Nuts not only contain valuable unsaturated fatty acids, high-quality proteins and other vital substances such as vitamin E, they are also a good source of calcium (content in mg per 100g):

• Almond nutter 347
• Hazelnuts 114
• Sunflower seeds 87
• Pumpkin seeds 52
• Coconut meat, dried 27

Calcium requirement

The human body needs around 300 to 400 mg of calcium per day. However, only a third of the calcium that we ingest with food is actually used by the body. Medical associations therefore recommend that adults take 700 to 1200 mg of calcium a day.

On one hand, the need depends on the age. Also, the current living situation must be included in the calculation. Pregnant or breastfeeding women have a higher need. The same applies to competitive athletes, women after menopause and people who drink a lot of alcohol. However, the German Nutrition Society does not take this into account in its recommendations.

Calcium requirement in adults in mg per day according to DGE:

• 19 to 25 years: 1200
• 19 to under 25 years: 1000
• 25 to under 51 years: 1000
• 51 to under 65 years: 1000
• 65 years and older: 1000

Calcium requirement in children

Both infancy and puberty are characterized by particularly intensive growth of the bones. Around 90% of the maximum bone mass is created during this time. Correspondingly large amounts of calcium are required.

In the first 5 to 6 years of life, children need an average of 100 mg of calcium per day just to build their bones. During puberty, the need for building up bone mass can only increase up to 400 mg per day.

During this sensitive phase, special attention should therefore be paid to an adequate calcium intake. If the food intake is insufficient, a nutritional supplement can be used to support bone growth.

The Skinner et al. study from 2003 reveals another positive effect of calcium during childhood and adolescence. The researchers were able to find a connection between calcium intake and obesity. Children who consumed more calcium had a lower body fat percentage.

Daily requirements for calcium in children and adolescents (in mg)

• 1 to under 4 years: 600
• 4 to under 7 years: 750
• 7 to under 10 years: 900
• 10 to under 13 years: 1100
• 13 to under 15 years: 1200
• 15 to under 19 years: 1200

Calcium requirement during pregnancy

The recommended total intake according to the guidelines of the German Society for Nutrition with 1000 mg is not above normal needs. However, various studies show that a low calcium intake can increase the risk of gestosis and eclampsia.

Gestoses are pregnancy-related diseases, the causes of which are still unclear. Hypertension, increased protein excretion in the urine, water retention, vomiting, headache and pain in the right upper abdomen are typical symptoms.

Eclampsia mainly occurs in the last trimester of pregnancy. Shortly after birth or in the puerperium, women can develop eclampsia with life-threatening seizures. Calcium supplementation during pregnancy can significantly reduce the risk of gestosis or eclampsia.

Calcium is mobilized from the mother's bones to meet the unborn child's calcium requirements. This is around 30 g throughout pregnancy. This leads to an average bone loss rate of 5%. During pregnancy, women should consume a particularly large amount of calcium-containing foods and/or consider taking supplements.

Calcium requirement in case of illness

The calcium requirement can be increased for various diseases. This is the case, for example, with thyroid diseases that are associated with an increased release of the hormone calcitonin. Calcitonin is formed in the thyroid gland and among other things ensures an increased excretion of calcium in the urine.

Increased calcitonin values are found in thyroid gland cancers and in rare cases with an overactive thyroid gland (hyperthyroidism). Cirrhosis of the liver or renal insufficiency can also lead to increased levels of calcitonin in the blood.

Calcium requirement for excess cortisol

People with Cushing's disease also have an increased calcium need. Cushing's disease is characterized by an abnormally increased production of the hormone cortisol. The main cause is benign tumors of the pituitary gland, tumors of the adrenal glands can also produce cortisol.

With cortisol, the parathyroid hormone increases in the blood. Parathyroid hormone mobilizes calcium from the bones. This is why patients with Cushing's disease often also suffer from osteoporosis. To counteract bone loss, doctors therefore recommend taking calcium.

Calcium requirement for inflammatory bowel diseases (IBD)

Inflammatory bowel diseases such as Crohn's disease and ulcerative colitis damage the intestinal mucosa. This means that nutrient intake is only possible to a limited extent. The reabsorption of bile acids is also impaired in patients with IBD.

Usually, these are absorbed through the intestinal mucosa and returned to the liver. If this so-called enterohepatic circulation does not work, more bile acids remain in the intestine. These bind calcium, so that the essential nutrient is excreted in the stool together with the bile acids. To safely meet their calcium needs, people with IBD need to take more calcium.

There are currently no recommendations regarding calcium requirements for people with chronic diseases. A consultation with a doctor is advisable here.

Calcium overdose

An overdose with calcium is usually not possible. If there is an excess, then this is excreted through bowel movements. Hypercalcaemia, e.g. too high a calcium level in the blood, is more likely to develop in another way.

The most common cause is bone loss with an increased calcium release due to malignant cancer. Hyperparathyroidism, e.g. an increased release of parathyroid hormone, can also increase blood calcium levels. The diseases acromegaly and pheochromocytoma also often result in hypercalcaemia.

Those who supplement very high doses of vitamin A or vitamin D and calcium at the same time can trigger hypercalcaemia. The early symptoms of this increased calcium dose in the blood include:

• Muscle weakness
• Fatigue
• Difficulty concentrating
• Nervousness and depression

Later, affected people suffer from nausea or constipation. Stomach ulcers can also develop, as can inflammation of the pancreas. The high calcium level leads to an increased amount of urine. The loss of fluid and the deposition of calcium crystals in the kidneys can cause kidney damage. If hypercalcaemia is not treated, there is a risk of damage to the nervous system or you can suffer from a coma.

The following daily dose should not be exceeded depending on age (in mg):

• 0 to 6 months: 1000
• 7 to 12 months: 1500
• 1 to 8 years: 2500
• 9 to 18 years: 3000
• 19 to 50 years: 2500
• 51 years and older: 2000

Calcium side effects

Calcium supplementation rarely has side effects and is usually well tolerated. People with a sensitive gastrointestinal tract can develop bloating or constipation. Some studies have also found a connection between calcium supplementation and the development of kidney stones and cardiovascular diseases.

Calcium interactions with medication and dietary supplements

• Antacids like proton pump inhibitors: Inhibits calcium absorption. Calcium supplementation can be useful to reduce the risk of osteoporosis.
• Antibiotics (especially tetracyclines, cephalosporins and gyrase inhibitors): Inhibits calcium absorption and increase excretion. The calcium supplementation should be done with an interval of 2 to 4 hours.
• Anti-epileptics: Reduces calcium absorption in the intestine due to a vitamin D deficiency.
• Glucocorticoids such as prednisolone: Inhibits calcium absorption and increase calcium excretion.
• Thyroid medication (e.g. L-Thyroxine): Calcium can reduce the absorption of thyroid hormones. You should take this at least 2 hours apart.
• Calcium channel blocker for the treatment of heart diseases: Highly dosed calcium can reduce the effect.
• Loop diuretics (diuretics): Increases the excretion of calcium.
• Diuretics (thiazides): Increases the blood calcium levels by reducing excretion.
• Heparin (anticoagulant): Long-term therapy increases the risk of osteoporosis. Adequate calcium intake is therefore important.