Why Is Dietary Calcium so Important for Children?

In their book “Kinderernährung – Expertenwissen für den Alltag” (German only), Swiss nutrition experts Dr George Marx and Andrea Mathis give a comprehensive overview of the wide-ranging and often controversial topic of child nutrition. We translated a selection of their insights and publish their findings on this blog to make them available to a wider audience. Please find the links to further posts of this series at the end of this contribution.

Calcium is an important mineral that in our body is found mostly fixated in our skeletal bones. Quantitatively, it is the most abundant mineral, and it plays an important role in blood coagulation (clotting) and in the activation of various enzymes and hormones in the body. It is also important for the formation, growth and regeneration of bones and teeth. In order for calcium to be optimally absorbed and incorporated into the bones, vitamin D is required. Bone metabolism constitutes a constant process of building up, breaking down and remodeling.

Milk and dairy products are good sources of calcium and should be fixtures in a healthy diet. Mineral water with more than 30 mg of calcium per 100 ml is also a good source of calcium. Here its bioavailability is about the same as in milk.
It is difficult – but possible with sufficient nutritional expertise – to meet calcium requirements without milk and dairy products.
As a matter of principle, a balanced healthy diet is of great importance. Use of medicinal products or substitutes should be avoided as much as possible, as most things can be optimized directly with the help of nutrition and common sense. In addition, it is important to pay attention to the topic of ‘exercise’ in the whole complex of bone development.

Photo: Nadja Lenherr

What is a good source of calcium if you cannot or do not want to have dairy products?

Calcium-rich vegetables such as broccoli, all types of round cabbage (e.g. red cabbage, savoy cabbage), green cabbage, Chinese cabbage, pak choi, kai choi, choi sum, algae (Asian), calcium-rich mineral water, calcium-enriched alternative drinks such as rice, oat, soy, almond and spelt drinks, or convenience products (ready-to-eat and ready-to-serve foods) with added calcium. Convenience products are not intended to serve as regular sources of calcium. They often contain hidden fat or sugar. It is important to consider possible effects on weight gain.

Is calcium bioavailability (readiness for absorption) higher in calcium-rich vegetables than it is in products made from cow milk?

Calcium bioavailability in the above-mentioned vegetables is very high. For example, in broccoli it is about 60%, in pak choi 50%, and in kale 49%. Spinach, chard and rhubarb have a calcium bioavailability of only 5 to 8%. The bioavailability of milk calcium, by contrast, is 30%. This means that 30% of the calcium contained in the milk will be absorbed; the rest is lost.

Can vitamin D positively influence the calcium balance?

Those who do not have a sufficient supply of vitamin D may suffer calcium deficiency despite optimum calcium supply, because only in the presence of vitamin D can calcium be absorbed from the intestine. Vitamin D is the so-called sun vitamin, which is formed in the skin with the help of UV irradiation. Only a small portion of the required vitamin D is supplied with food. Vitamin K2 also seems to play an important role in calcium metabolism.

Are there any calcium uptake inhibitors?

Yes. These include: Caffeine* (in coffee and tea, also iced tea), oxalic acid (in rhubarb, spinach, chard, purslane, cocoa), phytic acid (e.g. in cereals, pulses), alcohol*. A diet high in protein also inhibits calcium absorption in the intestine.
(*Caffeine and alcohol are mentioned for completeness only. Of course they do not belong into children’s diet.)

Please feel free to download this tasty, healthy and easy-to-prepare recipe which will soon be a favorite of your children!

Please check out the other posts of our series here: