Calcium (Ca) is one of the most well-known minerals and most strongly represented minerals in the human body in terms of quantity. A calcium deficiency in the human body is understood to be a concentration of calcium in the blood serum that is too low, i.e. less than 2.3 mmol/L (millimoles per litre).
It is recommended that adults take in 1,000 mg of calcium daily via food intake. Milk and milk products are good sources, but plant-based foods as well as certain mineral waters also provide a contribution towards calcium supply.
Calcium is required for many bodily functions. It plays an important role in blood clotting, muscle and nerve activity, defence against inflammations and allergies as well as the function of heart, lungs and kidneys. But perhaps the most well-known task of the essential mineral is the development and preservation of bones and teeth. About 99 % – approximately 1.2 kg – of the total amount of calcium in the body is in the bones and teeth.
Bones are living tissue that is subject to constant development and decomposition processes. There is a dynamic balance in which bone minerals are absorbed from the blood vessels and released again.
If not enough free calcium is available in the blood vessels, the body falls back on the calcium reservoir and removes it from the bones. So the concentration of calcium in the blood is initially kept in the normal range in case of insufficient calcium intake.
A more long-term calcium deficiency can lead to a decalcification of bones and teeth, which among other things can result in an increased risk of bone fractures and bone deformations. Osteoporosis (bone loss) can also be a possible consequence of a deficiency.
Causes of calcium deficiency
The basic prerequisite for healthy bone tissue is a sufficient supply of nutrients such as calcium and phosphate, because they are the main constituents of bones. They give the bone matrix its stability.
Hormonal disorders such as parathyroid hormone, oestrogen or testosterone are a frequent cause of a calcium deficiency as well as a vitamin D deficiency.
Since our body cannot produce the mineral calcium itself, it is imperative to ingest it regularly and sufficiently via food intake.
However, the German “National Consumption Study II” (Nationale Verzehrsstudie II) revealed that men with an average consumption of 807 mg of calcium as well as women with an average consumption of 738 mg of calcium are below the daily recommended intake. Only about two-thirds manage to cover their calcium requirement via food intake.
Women in the course of and after menopause should pay particular attention to an ample supply of calcium, because then certain hormones such as oestrogen decrease in concentration. But this controls the absorption of calcium in the bone structure.
The following causes can lead to a calcium deficiency:
- Calcium-deficient diet
- Vitamin D deficiency
- Hormonal disorders
- High coffee or alcohol consumption
- Increased calcium requirement (pregnancy, breastfeeding, puberty)
- Disorders of calcium utilisation and absorption
- Magnesium deficiency
- Elevated phosphate level
- Kidney diseases
- Thyroid diseases
- Medications (e.g. diuretics, cortisone)
- Digestive disorders
- Competitive athletes with high sweat losses
Symptoms of calcium deficiency
Since calcium is involved in many different bodily functions, symptoms of a calcium deficiency are also very varied. The intensity and duration of a deficiency also play a role.
The following symptoms can be indicative of a calcium deficiency:
- Muscle cramp, muscle tremor
- Cardiovascular problems
- Brittle fingernails
- Alterations of skin and hair
- Caries, periodontitis
- Digestive disorders
- Psychological disorders
- Disturbances in bone metabolism
- Osteoporosis, rickets
A person loses about 300 mg of calcium every day via sweat, urine and stool. How much calcium we should take daily depends on age, sex and hormones, among other things. Adolescents have a particularly high calcium requirement, since bone mass is still continually increasing.
But the requirement during pregnancy and breastfeeding is also increased, since the unborn child requires the mineral for development of bone structures. If not enough calcium is available in the blood vessels, the body falls back on the reserves in the bones of a pregnant woman.
Reference values for the daily requirement of calcium:
|Infants||220 – 330 mg|
|Children ages 1-3||600 mg|
|Children ages 4-7||750 mg|
|Children ages 8-9||900 mg|
|Children ages 10-12||1,100 mg|
|Adolescents ages 13-18||1,200 mg|
|Pregnant women / breastfeeding mothers (< age 19)||1,200 mg|
Calcium deficiency – vitamin D for the utilisation of calcium
A vitamin D deficiency is one of the most common causes of a calcium deficiency. Calcium in the body is primarily absorbed in the intestines. In this connection, vitamin D (cholecalciferol) promotes the absorption from the small intestine and the integration of calcium in the bones.
Vitamin D thus plays a very crucial role in the resorption of calcium – an adequate calcium intake would not be possible without this. That is why vitamin D is also referred to as an “integration helper” for calcium in the bones and teeth.
Vitamin D is for all intents and purposes not a vitamin at all, but the precursor of a hormone that the body can produce itself. The basic prerequisite for this purpose is sunlight, because the exposure of ultraviolet light to our skin cells leads to the formation of vitamin D, and over further processes in the kidneys and liver it leads to the production of the active substance, called calcitriol.
Unfortunately, the German “National Consumption Study” shows that 91 % of women and 82 % of men are not sufficiently supplied with vitamin D. Even Germany’s geographical location with too little solar radiation in the winter months complicates an adequate supply situation.
In particular, elderly people particularly often have low vitamin D levels, because self-production in the body decreases with increasing age.
That is why regular consumption of food rich in vitamin D is highly advisable, whereby it is found in relatively few foodstuffs. For example, cod liver oil and fat-rich fish as well as eggs and various types of mushrooms are sources of vitamin D.
In order to regulate the vitamin D balance in case of insufficient solar radiation, dietary supplements are also recommended.
Prevent calcium deficiency – calcium in foodstuffs
Milk and milk products are among the most well-known foodstuffs rich in calcium. Even 200 ml of cow’s milk provides about 240 mg of calcium and thus already covers nearly a fourth of the daily calcium requirement. Incidentally, the fat content of milk does not play a role, since the mineral content is not influenced by this.
Cheeses – particularly hard and semi-hard cheeses such a Parmesan, Emmentaler or Tilsiter – are particularly rich in calcium. For example, a 30 gram slice of Tilsiter provides about 250 mg of calcium.
But we can also cover our calcium requirement by means of plant-based foodstuffs. In particular, green leafy vegetables such as kale, rocket salad or fennel are recommendable, but herbs such as parsley as well as nuts and seeds also contribute towards targeted calcium supply.
Many people are not aware that mineral water can also be a good source of calcium. Mineral waters particularly rich in calcium can contain over 500 mg of calcium/litre. Mineral water with a content of 150 mg of calcium/litre or more may be called rich in calcium.