Calcium

There’s more to it than bones and teeth

By Patrick Isaacs

When most people think of calcium they immediately think of bones and teeth. That’s fair enough but remember that this mineral is absolutely essential for many other body functions and for good performance in sport.

If your grandmother was like mine, then maybe you heard the same refrain I did every morning: “drink your milk or your teeth will fall out and you won’t grow”. That wonderful woman gave me the same sermon at breakfast every morning, perpetuating the tradition of linking milk with the formation of strong bones and teeth. As is well known, this white liquid food was, and still is, considered the best calcium source.
Now my grandmother was not necessarily wrong, but today we know that milk is not the only rich calcium source and that this mineral is important not only for the bones and teeth. So let’s take a closer look at why.

Calcium and bones
Calcium is the most abundant mineral in your body. Indeed, if you weigh about 70kg then you are carrying around about 1.3kg of calcium, and 99% of it is in your bones and teeth. And don’t think the remaining 1% is unimportant. Up to 13g of calcium is also used in your body for extremely important metabolic functions.
Young people who are busy growing bones should therefore take in at least the recommended 1200mg of calcium through their diet each day. For adults the recommended daily dietary intake of calcium is 800mg. Yet in countries such as the United States most people fail to take in enough calcium to ensure a ready supply for those important body functions.
Though the 1% of calcium found outside the bones and teeth sounds small, it is in fact immense compared with other essential minerals used in the body. It is vital for the transmission of nerve impulses, muscle contraction and a huge variety of vital functions.
Your skeleton is where your body stores a reserve of calcium. Problems can arise when your calcium intake is too low because your body then robs your bones in order to maintain adequate calcium levels elsewhere, such as in your plasma. This happens immediately if even for a day these delicate levels of calcium fall too low. Straightaway the body turns to the bones to get some calcium and in the process weakens them. When calcium comes in through the diet again the body “repays” the calcium to the bones.
But when this “bone-raiding” happens too often, or more is consistently taken than is replenished, you get the now somewhat infamous osteoporosis. This disease, suffered by millions, is characterized by bones that are porous, weak and fragile, due to a lack of calcium. Though mainly affecting women, men are also among its victims.
Despite worldwide sales of millions of calcium supplements, osteoporosis has not been reduced as expected because calcium by itself cannot form a single bone molecule. In order to make bone from calcium the body also needs suitable levels of magnesium, fluoride, zinc, copper, boron, manganese, silicon and vitamin D.
Although a basic fact recognized by scientists, many members of the general public ignore the biological law that no biochemical action can take place without a specific action of synergy between different, and sometimes many, nutrients.

Making bones stronger
The human body, an absolutely fascinating machine, starts to disintegrate without some sort of stress. If stress is consistently applied in a particular area then new molecules will be developed there in response. The more tension applied to the bones the stronger they become, much like the same overcompensation reaction that produces muscle growth.
This is precisely why training with weights or loads, which obviously puts a stress on the bones by making them support more weight, spurs an increase in bone density and significantly strengthens the skeleton. 

The other functions of calcium
Clearly calcium is an element essential for the bones but it also plays a critical role in many other important body functions. For example, it is essential for cell division, maintaining a healthy immune system, enzyme activity and the production and activity of hormones used in digestion. Calcium also has a part in the production of saliva, the metabolism of energy and fat, and is utilised in the transport of nutrients and other substances through cell membranes.
Furthermore, this mineral reduces blood and stomach acidity and promotes sleep.
When it comes to sport, a lack of calcium translates into a lack of physical power. You need calcium so that the body’s energy-producing systems can operate correctly and allow optimum physical and sporting performance.
In addition, the muscles will not be able to contract fully if calcium levels are sub-optimal.
Several recent studies suggest that calcium also helps in the elimination of body fat.
Absorption, metabolism and deficiencies
On average, an adult absorbs just 25-50% of the calcium in their diet. Some of this is absorbed passively and the rest relies on help from vitamin D, which, among other things, helps transport calcium through the bloodstream. Most calcium is absorbed in the small intestine and then moves to the calcic deposits in the body fluids that the body uses according to its needs. Blood calcium levels are closely regulated by the hormones calcitonin and parathyroid, as well as by vitamin D. Other hormones that also affect the calcium levels include oestrogen, glycocorticoids, thyroid, insulin and growth hormone.
Smoking and consuming refined sugar, caffeine or alcohol each promote excretion of calcium from the body, thereby raising the risk of deficiency. Although there are conflicting opinions on the matter, some experts warn that excessive consumption of meat protein may also elevate the risk of calcium loss.
Moderate calcium deficiency can cause nervous sensitivity, muscle cramps and twitches, brittle nails, irritability, palpitations and insomnia. When the deficiency is severe the symptoms include an abnormal heart rate, muscle pains and cramps, numbness, rigidity, tingling or a "pins-and-needles" feeling in hands and feet, as well as depression.
In children, rickets, bone deformation and growth retardation can occur, and in adults, osteomalacia with bone pain, muscle weakness and slow-healing fractures.
 Calcium sources
Milk and milk products are among the best calcium sources but by no means the only ones. Fish, nuts and vegetables (especially green-leaved ones) also provide good amounts of dietary calcium. Without going too far into it, several studies have shown that the body better absorbs calcium from kale than from milk.
Here are the reference values of the calcium content of some common foods:
 

Food	portion	calcium (mg)
Whole milk, powdered	1 cup	658
Salmon, tinned	1/2 cup	484
Sardines, tinned	5 units	455
Skim milk, powdered	1/2 cup	377
Yoghurt	1 unit	338
Skim milk	1 cup	297
Whole milk	1 cup	291
Cheddar cheese	1 slice	204
Tofu	1/2 cup	204
Crabmeat, tinned	1 cup	136
Figs, dried	5 units	135
Peanuts	1/2 cup	134
Peas, tinned	1 cup	127
Kale, cooked	1 cup	94
Walnuts	1 cup	94
Almonds	1/2 cup	89

Calcium is the most abundant mineral in the human body and essential for numerous biological functions, a strong skeleton and to ward off the risk of osteoporosis.
A balanced, calcium-rich diet promotes your optimal health and helps ensure your physical prowess and muscle tone are the best they can be.
By the way, I always took my grandmother’s advice.