What is calcium?

Calcium is the most abundant mineral in the human body and plays a crucial role in bones, teeth, muscles, nerves, and metabolism . Approximately 99% of calcium is found in bones and teeth, where it serves as a structural and strengthening element . The remaining 1% is located in the blood, muscles, and intercellular spaces – there, calcium regulates vital functions such as muscle contraction, nerve conduction, and blood clotting .

Since the body cannot produce calcium itself, it must be regularly supplied through food . A balanced calcium intake is particularly important during growth phases, pregnancy, breastfeeding, and in old age to maintain bone density and muscle function .

How does calcium work in the body?

1. Formation and maintenance of bones and teeth:
Calcium is the main component of the bone mineral hydroxyapatite , which gives bones their hardness and stability. Together with vitamin D, magnesium, vitamin K, and phosphorus, it ensures continuous bone regeneration. A constant exchange of calcium takes place in the body between the bones and the blood – a process that is particularly regulated by vitamin D.

2. Muscle contraction:
Calcium controls muscle contraction – including the heart muscle. It ensures that muscle fibers actively contract and relax again after exertion. A calcium deficiency therefore often leads to muscle cramps or tremors .

3. Nerve conduction:
Calcium is crucial for the transmission of electrical signals between nerve cells. It enables the release of neurotransmitters and thus communication between the brain, muscles, and organs.

4. Blood clotting:
Calcium is involved in several steps of the coagulation cascade and helps to close injuries by supporting the formation of fibrin (blood clots).

5. Cell metabolism and enzyme activity:
Calcium acts as a signaling molecule in cells , activating numerous enzymes and controlling hormonal processes, such as the release of insulin.

6. Heart rhythm and blood pressure:
Calcium contributes to the regulation of the heartbeat and can stabilize blood pressure by influencing the contraction of blood vessels.

Benefits of adequate calcium intake

• Supports strong bones and teeth

• Promotes muscle contraction and relaxation

• Contributes to normal nerve function

• Supports blood clotting and wound healing

• Regulates heart rhythm and blood pressure

• It has a preventative effect against osteoporosis

• Supports energy and enzyme metabolism

Calcium-rich foods

Animal sources:

• Milk, yogurt, cheese (especially hard cheeses like Parmesan or Emmental)

• Sardines or salmon (with bones)

Plant sources:

• Kale, broccoli, spinach, bok choy

• Almonds, sesame seeds, chia seeds

• Mineral water with a high calcium content (> 150 mg/L)

• Legumes (e.g. white beans, chickpeas)

• Fortified plant-based milk alternatives (e.g. soy or oat drink with calcium)

Recommended daily intake

According to the German Nutrition Society (DGE):

• Adults: 1000 mg calcium per day

• Adolescents (13–18 years): 1200 mg/day

• Elderly people, pregnant women, breastfeeding women: up to 1200 mg/day

A consistent intake throughout the day improves absorption.

Calcium absorption and utilization

The following nutrients are important for optimal calcium absorption:

• Vitamin D: improves calcium absorption in the intestine and its incorporation into the bones

• Vitamin K2: ensures that calcium is incorporated into bones instead of blood vessels.

• Magnesium: supports calcium metabolism and prevents muscle cramps

• Phosphorus: acts synergistically in bone metabolism (but too much inhibits absorption)

Deficiency symptoms (hypocalcemia)

Calcium deficiency can occur due to:

• insufficient supply

• Vitamin D deficiency

• hormonal disorders (e.g., parathyroid disease)

• certain medications (e.g. diuretics)

Typical symptoms:

• Muscle cramps, tremors

• Numbness in hands or face

• Brittle nails, bone weakness

• Dental problems

• Osteopenia or osteoporosis due to chronic deficiency

Overdose (hypercalcemia)

Excessive calcium intake (usually through dietary supplements) can lead to:

• Nausea, vomiting

• Kidney stones

• Calcium deposits in blood vessels lead to
  In the long term, there is an increased risk of cardiovascular disease if calcium is ingested without sufficient vitamin K2.

Conclusion

Calcium is essential for strong bones, stable muscles, healthy nerves, and a healthy heart. A balanced diet including dairy products, green vegetables, nuts, and calcium-rich mineral water reliably covers daily requirements. In combination with vitamins D and K2 , calcium makes a crucial contribution to bone health, performance, and overall vitality – throughout life.

Sources

1. German Nutrition Society (DGE). (2020): Calcium – Reference values ​​for nutrient intake.

2. Weaver CM. (2014): Calcium supplementation: is protecting against osteoporosis counter to protecting against cardiovascular disease? Curr Osteoporos Rep , 12(2), 211–218.

3. Heaney RP. (2009): Factors influencing the measurement of bioavailable calcium in humans. J Nutr , 139(9), 1636S–1639S.

4. Lips P, Cashman KD, Lamberg-Allardt C, et al. (2019): Current vitamin D status in European and Middle East countries and strategies to prevent deficiency. Endocr Connect , 8(2), R55-R75.