Article Series

  1. Calcium For Bones And Teeth / Improve Absorption
  2. Calcium Daily Requirement
  3. Calcium Deficiency - Causes, Symptoms, Treatment

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Calcium Deficiency - Causes, Symptoms, Treatment

Calcium Deficiency - Causes, Symptoms, Treatment
Table Of Contents
  1. Risk Groups
  2. Causes of calcium deficiency
  3. Milk as a cause of calcium deficiency
  4. Symptoms of Calcium Deficiency
  5. Consequences of Calcium Deficiency
  6. Detecting Calcium Deficiency / Diagnosis
  7. Treatment
  8. Preventive Measures

The mineral substance calcium is indispensable for the body. It truly plays a crucial role. Calcium is the substance our body needs for strong bones and teeth. Moreover, it is essential for numerous functions such as muscle contractions. When the body experiences calcium deficiency, it can lead to severe health damage.

Risk Groups

Risk groups include omnivores and vegetarians who rely on animal-derived products, especially dairy products. They are often promoted as the number one source of calcium without considering the health consequences (see causes).

Vegans who have a less varied diet and consume excessive amounts of foods containing oxalic and phytic acid have lower levels of calcium 1 2 3 4 5 6 7.

People who have insufficient vitamin D in their body (biologically active form: calcitriol) require vitamin D for calcium absorption from food. The important vitamin can be produced through the skin in our latitudes during the summer months. However, this is not possible during the winter months due to the unfavorable angle at which the sun's rays penetrate. Therefore, it is important to rely on plant-based foods with vitamin D during the winter months. A vitamin D deficiency can also be attributed to other causes such as intestinal diseases that result in reduced absorption of vitamin D.

Elderly individuals have a harder time absorbing calcium from food as they age. Therefore, it is usually recommended for them to consume more calcium throughout the day through their diet.

Pregnant and lactating women also have an increased need for calcium, which should be compensated for through their diet.

Athletes or individuals who sweat a lot lose higher amounts of calcium through sweat.

Causes of calcium deficiency

Hypocalcemia is often due to health problems such as reduced absorption in the digestive tract (usually in advanced age), vitamin D deficiency (which is required for calcium absorption), and inadequate calcium intake from food. However, it can also be caused by intestinal or kidney diseases, as well as pancreatic impairment.

If the parathyroid glands are affected, it leads to a deficiency of parathyroid hormone (hypoparathyroidism; can also be genetically caused). Parathyroid hormone regulates the calcium levels in the blood. If it is not sufficiently released due to an underactive parathyroid gland, the calcium levels decrease because more calcium is excreted and less calcium is absorbed in the digestive tract.

However, a magnesium deficiency (hypomagnesemia) can also lead to a reduction in calcium concentrations in the blood. Magnesium is involved in the regulation of calcium levels in the blood. Thus, a magnesium deficiency impairs the secretion of parathyroid hormone (PTH) by the parathyroid glands and the responsiveness of osteoclasts (bone-resorbing giant cells) to parathyroid hormone 8.

Some plant-based foods such as grains, seeds, nuts, or vegetables like spinach and Swiss chard contain higher amounts of oxalic and phytic acid. These substances chemically bind to calcium, thereby reducing the absorption of calcium. Thus, an unbalanced diet can also contribute to a deficiency. However, cooking or steaming can somewhat reduce the negative effects of these acids. Here is a summary of foods that provide easily absorbable calcium.

In addition, caffeine, nicotine, alcohol, and sodium also lead to increased calcium excretion. Medications like proton pump inhibitors can also negatively affect calcium absorption, resulting in calcium deficiency 9.

Milk as a cause of calcium deficiency

In many cases, malnutrition is the cause of calcium deficiency. Interestingly, osteoporosis is more prevalent in countries where the largest amounts of calcium are consumed through animal products. Dr. T. Colin Campbell, who published the China Study, noted in this regard that Americans, unlike other population groups, consume much more milk and should therefore have strong bones. However, this is not the case. According to the study, American women aged 50 or older had the highest hip fracture rates. In Europe, as well as in Australia and New Zealand, where milk consumption is even higher, fracture rates were even greater. The increased risk of bone fractures is also supported by other studies 10.

In dairy products, there are high levels of acidic and sulfur-containing amino acids that cause the body to become acidic. This leads to the leaching of calcium from the bones to neutralize the acidic environment. Meat also contains many sulfur-containing amino acids that cause calcium to be lost through urine. They acidify the body, resulting in the release of calcium from the bones. Additionally, milk can contribute to various diseases such as osteoporosis and diabetes. Furthermore, milk increases the risk of ovarian and prostate cancer and mortality. 11 12.

Symptoms of Calcium Deficiency

Symptoms indicating calcium deficiency include 13 14:

  • Hair loss
  • Brittle nails
  • Dry skin
  • Loss of appetite
  • Neuromuscular irritability
  • Muscle cramps
  • Muscle twitches
  • Tingling fingers
  • Sleep disturbances
  • Cognitive impairments
  • Lethargy
  • In more severe cases, palpitations
  • Tetany (increased neural excitability)

Due to calcium deficiency, tetany often occurs, which results in motor and sensory disorders due to increased excitability of muscles and nerves. In the event of a tetanic attack, which manifests as restlessness, digestive disorders, diarrhea, numbness, facial muscle spasms (Chvostek's sign), hand contractions (Trousseau's sign), paresthesias (tingling and burning in fingers, arms, feet, legs, and face), and sensory disturbances, it can become life-threatening, for example, due to the spasming of the laryngeal muscles (laryngospasm). In such a case, immediate medical assistance should be sought.

Furthermore, a correlation has been found between calcium deficiency and an increased risk of developing kidney stones and colorectal cancer. The likely cause is a decreased binding capacity and increased absorption of oxalic acid. Oxalic acid is the main component of kidney stones and carcinogens such as bile acids 15.

Consequences of Calcium Deficiency

If the calcium deficiency remains undetected for a prolonged period, it initially leads to osteopenia (reduction in bone density) and subsequently to osteoporosis (release of calcium from the bones). This results in a decrease in bone strength, leading to an increased risk of fractures and back pain due to porous bones. It should be noted that osteoporosis is not solely attributed to calcium deficiency but can also have other causes (e.g., hormonal changes and lack of exercise).

In childhood, calcium deficiency can lead to rickets. Rickets is usually caused by a deficiency of vitamin D.

Other consequences of prolonged calcium deficiency can include poor blood clotting and clouding of the lens in the eye (cataract, commonly known as "gray star").

If hypocalcemia is left untreated, depending on the duration, severity, and speed, calcium deficiency can become life-threatening 16.

Detecting Calcium Deficiency / Diagnosis

A calcium deficiency is diagnosed by a doctor. They measure the calcium concentrations in the serum. The table below shows the serum concentrations indicating a deficiency 17 18:

ConditionSerum Calcium Concentration
Normal 2.12-2.60 mmol/l
Deficiency (Hypocalcemia) < 2.12 mmol/l (< 8.5 mg/dl)
(corrected serum concentrations)

Serum calcium concentrations must be interpreted in relation to serum albumin concentrations 19. Approximately half of the total serum calcium is bound to the protein albumin, and the remaining ∼50% is free ionized calcium, which is physiologically active 20.


If a deficiency is identified, primary treatment often involves vitamin D (including Alfacalcidol and Calcitriol), magnesium (to stimulate parathyroid hormone release), and calcium supplements (calcium carbonate and calcium citrate) to improve calcium absorption 21. Depending on the cause and severity, other measures such as injections and long-term care by a treating physician may also be necessary. Only when the cause is known can appropriate treatment be administered; otherwise, only the symptoms of calcium deficiency are temporarily alleviated.

The most helpful measure for healthy individuals with mild deficiency is to meet the calcium requirement through a healthy and balanced diet, taking into account that the body has sufficient vitamin D and magnesium. The correct magnesium-to-calcium ratio is 1:2 22.

The treatment of hypocalcemia (secondary) and hypoparathyroidism can be intensified through the use of thiazide diuretics, phosphate binders, as well as a low-salt and low-phosphorus diet (low-phosphorus foods) 23.

Preventive Measures

The most sensible measure is to provide the body with sufficient calcium through calcium-rich foods. Daily calcium requirements should be ensured, which is not a problem with plant-based foods. Furthermore, a vegan diet reduces the risk of osteoporosis.

In addition, there are several ways to positively influence calcium absorption. Along with the crucial vitamin D, vitamins C, E, K, and the mineral magnesium are involved in improved calcium uptake 24.

Studies have shown that higher amounts of potassium salts, primarily found in fruits and vegetables, reduce calcium excretion through urine, allowing the body to retain more calcium 25.

Aside from a mindful diet, it is crucial to strengthen the bones through plenty of exercise. This helps build bone mass through repetitive stress.