Over nine million packs Calcium preparations go every year over the counters of German pharmacies. In addition, there are offers from drugstores and supermarkets. The fear of osteoporosis and the advertising of the pharmaceutical companies make many reach for the daily extra portion. Do we really need so much of the mineral, or can too much calcium even be harmful??
Calcium: Important for bones, teeth and more
Calcium is of utmost importance for the human organism. Together with phosphorus, it has become the most important building material for bones and teeth. 99 percent of all calcium in our body is found in these hard tissues. The rest is dissolved in blood and tissue. Calcium ions perform vital tasks there: They are crucial for blood clotting, the excitability of nerve and muscle cells, and stabilize cell walls.
As message transmitters within cells, they also activate numerous enzymes. Because calcium ions are necessary for many processes in the body, the organism keeps the calcium level in the blood within very narrow limits. This is achieved through a complex interplay of various hormones, primarily parathyroid hormone, vitamin D hormone (calcitriol) and calcitonin. Estrogens, androgens, thyroid and growth hormones, cortisol and insulin are also involved. If too little calcium is supplied, the organism falls back on its emergency reserve, the bone tissue. Under the influence of parathyroid hormone, calcium ions are then released from the bones to prevent the blood level from dropping. In this way, with a persistent undersupply of calcium, bone substance is lost.
Preventing calcium deficiency – how much calcium is necessary?
On average, we excrete 300 milligrams of calcium every day through urine, stool and sweat. This loss must be compensated for through food. The German Society for Nutrition recommends 500 milligrams of calcium per day for infants and 900 for adults. People with an increased need should take more: Adolescents in the growth phase and pregnant women 1200 milligrams and breastfeeding even 1300 milligrams daily. These recommendations take into account that the body absorbs only 20-40 percent of the calcium it contains from a mixed diet. The utilization of the mineral is therefore by no means optimal. How much we actually absorb depends on several factors: Age, gender, current calcium requirements, hormonal balance and dietary composition promote or inhibit calcium absorption. Babies absorb 75 percent of the mineral from breast milk, and men generally utilize dietary calcium better than women. Certain substances in plants, such as phytic and oxalic acids, form poorly soluble complexes with calcium and impair absorption.
An important partner of calcium: vitamin D
The decisive role in the absorption of calcium is played by vitamin D, without which it is not possible to absorb it as required. Only a few foods such as butter and fatty fish contribute to vitamin D supply. For once, in the case of vitamin D, humans do not depend exclusively on food: The vitamin is formed in the skin from a precursor formed in the body when there is sufficient sunlight. The actual active form of the vitamin, the vitamin D hormone, is then formed in the kidneys. The hormone causes the formation of a protein in the intestinal wall, which transports the calcium ions from the intestine into the blood. In the case of vitamin D deficiency, less calcium is absorbed, with serious consequences for bone mineralization. If children do not take in or produce enough vitamin D, bone deformation, rickets, occurs.
Ratio of calcium and phosphorus
The ratio of calcium and phosphorus in the diet is also important for good calcium utilization. Phosphorus or. Phosphate is absorbed at 60 percent and is superior to calcium in this respect. If much more phosphate is taken in than calcium, the phosphate content of the blood increases. As the body strives to maintain a balanced calcium-phosphorus ratio in the blood, it mobilizes calcium from the bones to compensate for the imbalance. In addition, the absorption of calcium is reduced by high levels of phosphate in the diet. Therefore, the phosphate content of the diet should not significantly exceed that of calcium. This is not a problem with a balanced, natural diet. However, with today’s diets rich in meat and sausage, convenience foods, and soft drinks, phosphate intake is often higher than calcium intake.
1000 mg calcium are contained in:
|100 g wholemeal pasta
30 g parmesan
250 g broccoli
20 g poppy seed
100 ml buttermilk
∑ 1000 mg calcium
|or||200 grams of yogurt
30 g almonds
200 g wholemeal bread
35 g Emmental cheese
200 g fennel
∑ 1000 mg calcium
With the right choice of foods, it is no problem to reach the recommended amount of about one gram of calcium daily to come. Even an increased requirement can be covered by food and suitable beverages.
Calcium from pills or through food?
Take easily soluble calcium salts, acidifiers, sugar substitutes and sweeteners, a little color and flavor – and the mineral tablet is ready. Calcium carbonate, calcium lactate or calcium gluconate, whose absorption rate is 30 percent, are frequently used. Fortified fruit juices usually contain calcium citrate malate, which is somewhat more available due to its acidity. Sorbitol, a sugar substitute found in many sweets, on the other hand, reduces calcium utilization and triggers abdominal cramps and diarrhea in some people. However, it is not necessary to use so many chemicals to ensure an adequate supply of calcium.
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Milk and dairy products such as yogurt and kefir are the most important sources of calcium in our diet, containing around 120 milligrams per 100 grams. At the same time, other ingredients such as lactose, vitamin D, lactic acid, and proteins promote the absorption of the mineral. The bioavailability from these foods is therefore very good at 30 percent. The same applies to cheese, which can contain up to 1200 milligrams of calcium per 100 grams, depending on how it is made. Hard and semi-hard cheeses are particularly rich in calcium. Vegetable foods also contribute to the calcium supply, which can be quite considerable if calcium-rich vegetables are selected in a targeted manner. From plants, the mineral is generally less utilized; the absorption rate is usually below 20 percent. Plant substances such as oxalic and phytic acids from vegetables, grains and seeds additionally reduce availability. Another liquid source of calcium should not be underestimated – mineral water. Calcium is present here in ionized form, in which the organism can absorb it well. From a content of 150 milligrams per liter, a mineral water may call itself rich in calcium.
Calcium supply in vegans: It also works without milk
Even those who eliminate dairy products from their diet for health, ideological or other reasons do not automatically have to take calcium tablets. However, alternative calcium sources such as kale, broccoli, almonds, sesame seeds and calcium-rich mineral water should be included in the diet.
Calcium deficiency in vegans – critical in young children
A consumption survey showed that vegans, who do not eat any animal foods, consume the least calcium compared to mixed-food and ovo-lacto-vegetarians. In individual cases deficiencies have been observed, but most vegans were adequately supplied. Presumably, an increased absorption rate as well as a low protein intake (see below) contributes to a positive balance. A very critical assessment must be made of the vegan diet for small children, who often only reach 50 percent of the recommended calcium intake. They should receive additional calcium, as should children who cannot tolerate dairy products because of a milk protein allergy. In infants and toddlers, special low-allergen foods based on soy or cow’s milk can be given, which are enriched with calcium and other nutrients. Soy drinks and milk without added calcium are not an equivalent substitute for cow’s milk because their calcium content is too low. Calcium-rich mineral water and fortified fruit juices can additionally increase the intake. But beware of allergies: Some of these juices contain milk protein. Allergy sufferers should therefore pay close attention to the list of ingredients. If children refuse the somewhat bitter milk substitute food and calcium-containing vegetables, it is advisable to cover their needs with a low-dose calcium preparation under medical supervision.
Ovo-lacto vegetarians best supplied with calcium
The situation is quite different for ovo-lacto-vegetarians, who also consume milk, dairy products and eggs. Here the calcium intake is usually above the recommended value. They are also better supplied than the average population, which predominantly takes in too little calcium. Fears that the high fiber content of the vegetarian diet could worsen the calcium supply were not confirmed. Both vegetarian diets also have the advantage that they contain less protein than a mixed diet. The lower protein intake lowers the excretion of calcium via the kidneys, so it has a saving effect. Conversely, high protein intake causes increased calcium excretion, worsening the balance.
Calcium: protection against osteoporosis?
Fear of osteoporosis is probably the main reason why many people take too much calcium calcium preparations fall back on.Especially women after menopause, but also men at an older age are affected by this disease. In osteoporosis patients, bone degrades faster than normal and becomes more susceptible to fractures. However, whether a high calcium intake really helps against osteoporosis is disputed in science. While many studies support the benefits of increased intake, others question its effectiveness. One thing seems certain, however: the estrogen deficiency that occurs after menopause triggers a rapid breakdown of bone substance. In the first five to seven years after the last menstruation, this process cannot be slowed down by a high calcium intake alone. Only at a later stage does calcium supplementation have a positive effect, i.e. bone resorption can be slowed down. However, this effect can also be achieved with calcium from the diet. A daily intake of 1000 to 1500 milligrams is crucial.
The real importance of calcium lies in prevention
Those who consume sufficient calcium from childhood mineralize their bones optimally. After the age of 30. no additional calcium is incorporated after the age of 30. In fact, the body then draws on the cushion that has been built up to that point. Osteoporosis is also promoted by too little physical activity. Plenty of outdoor exercise, so that vitamin D can also be formed at the same time, is therefore just as important as an adequate calcium intake.
Calcium preparations for calcium deficiency: Caution against self-medication
Calcium supplements are medicinal products and should not be taken lightly – certainly not as a tasty soft drink, as some suppliers advise on the packaging. They are only necessary in certain situations and for some medical conditions. If a Calcium Deficiency If the risk of kidney stones increases, the first thing to do is to take a close look at dietary habits. If an additional supply proves necessary, the dosage and duration must be discussed with the doctor.
An uncontrolled, Excessive calcium intake can do more harm than good. It worsens the absorption of iron, zinc and magnesium and can result in an undersupply of these important nutrients.If more than 1500 milligrams of calcium are supplied per day, the body excretes the excess with the urine. This can promote the formation of kidney stones and calcifications, especially in people with a predisposition or impaired kidney function. According to one study, the risk of kidney stones increased only if Calcium as a preparation has been taken. High levels in the diet reduce the risk of this happening. The authors attribute this astonishing result to the positive influence of certain substances such as calcium. B. phosphate, which are contained in dairy products. Prolonged overdosage of vitamin D combined with high calcium intakes of more than 2000 milligrams per day overcomes the natural absorption barrier and can result in an oversupply, known as hypercalcemia. The consequences range from loss of appetite and impaired consciousness to coma.
Anyone who believes they do not have an adequate supply of calcium and perhaps experience muscle cramps from time to time should consult a doctor. From self-medication according to the motto "much helps much" is not advisable in any case. Often, mineral pills are just a convenient method of not having to change cherished but wrong habits. A healthy lifestyle and diet is the best guarantee for taking in enough calcium and protecting oneself from osteoporosis – side effects or deficiency symptoms are excluded.
CURHAN, G. et al. Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones. In: Annals of Internal Medicine 7, Vol. 126, S. 497-503, 1997
DAWSON-HUGHES, B. et al.A controlled trial of the effect of calcium supplementation on bone density in postmenopausal women. In: The New England Journal of Medicine, S. 878-883, 1990
FEIEREIS, H.; SALLER, R. (ed.): 275 new, unpublished questions and answers from practice. Volume 3, Munich 1992
KASPER, H.: Nutritional medicine and dietetics. 7. Aufl., Urban and Schwarzenberg, Munich 1991 LEITZMANN, C.; HAHN, A.: Vegetarian diet. UTB, Stuttgart 1996