Calcium is an important major mineral that all living things, including people, need. It is the mineral that the body has the most of, and it is very important for bone health. People need calcium to build and keep their bones strong, and almost all of the calcium in the body is in the bones and teeth.
Calcium is referred to as a “macro-mineral,” which means that our food must provide us with literally hundreds of milligrams of calcium every day. The other macro-minerals that we must get from food daily are magnesium, phosphorus, sodium, potassium, and chloride. Minerals which are required in much smaller amounts are called the “trace elements”.
Most people know calcium to be the “bone mineral”, and understand that calcium is vital in their diet to ensure good bone health. However, this is only one aspect of calcium’s role in the human body. Calcium is the most abundant mineral in the body with the average male containing up to 1 ½ kgs and the average female up to 1 kg. About 99% of calcium is found in bones and teeth with the remaining 1 % in the soft tissues distributed throughout the body such as muscle, glands, and nerves where it helps to regulate normal processes of the body. This tiny percentage of calcium however, despite the relatively smaller quantity, is critical to human existence because this calcium plays a role in the beating of the heart, the action of every muscle, blood clotting as well as all nerve and hormone activity.
The public are often barraged with various public health messages encouraging the consumption of foods rich in calcium, aimed at preventing osteoporosis, a disease characterised by poor bone deposition causing brittle and porous bones which may easily lead to broken ribs, hips and long bones with minor falls. The leading causes of poor levels of calcium in humans in the 21st century is both a calcium-deficient diet and a decreasing ability to absorb calcium from the diet, particularly common in the Western world due to decreasing levels of hydrochloric acid (poor stomach and small intestinal function) and stress.
Calcium and the Musculoskeletal system – Calcium, combined with phosphate to form hydroxyapatite, is the main mineral portion of human and animal bones and teeth. Bone health is supported by many factors, most notably calcium and vitamin D. Knowing that about 99% of all the calcium in your body is found in your bones and teeth, you can understand the true significance of this mineral when it comes to the structural requirements of your body.
Calcium and Osteoporosis – Calcium supplements can help prevent fractures in older women, but only if patients are compliant, according to a 5-year, double-blind, placebo-controlled study led by Richard L. Prince, MD, of the University of Western Australia in Perth, Australia. Unfortunately, long term studies have found that poor compliance is one of the main reasons why calcium supplements fail to work consistently, particularly in the elderly. According to Dr. Prince:”all women at relatively high risk of minimal trauma fracture due to the fact that they have survived to 70 years of age should take calcium tablets twice a day for 5 years to reduce their risk of fracture of any bone”
Calcium Excites – Magnesium Relaxes – Calcium plays a critical role in the heart and skeletal muscle and plays an important role in the function of excitable tissue (muscle and nerves). Before the heart can “beat,” special cells in a region of the heart called the “sinoatrial node” (SA node) must spontaneously initiate an electrical impulse. This impulse then stimulates the rest of the heart to contract – and then finally beat. Calcium is fundamentally involved in initiating that impulse in the SA node. Calcium is also involved in the contraction of heart muscle, as well as contraction of skeletal muscle. In doing so calcium is the factor that initiates the physical action of heart beats and muscle movement.
Magnesium, on the other hand, serves as a chemical gate blocker in many of the body’s nerve cells. Magnesium helps to oppose the activity of calcium, preventing it from moving too quickly inside the cell and activating the nerve. This balanced activity helps to keep the nerves (and therefore muscles) relaxed. So now you see, if your diet provides too little magnesium, or if you deplete your body of too much magnesium (coffee, tea, junk foods, alcohol, sweet foods, candies, etc) then your nerves and muscles will pay the price. Nerve cells become over activated (over excited) with too little magnesium because this gate blocking calcium/magnesium mechanism fails.
Muscles over contract because too many messages are sent by the nerves to the muscles. This imbalance explains why a magnesium deficiency can trigger muscle fatigue and tension, muscle cramps and spasms and muscle soreness and weakness. Similarly, with too little calcium heart arrythmia can more easily occur, blood pressure can be more easily elevated, “bad” cholesterol can elevate and abnormal blood clotting may occur.
Calcium May Assist in Colon Cancer Prevention – Bowel cancer develops from tiny polyps that are the result of rapidly multiplying cells in the lining of the intestine. Why these cells develop into polyps is not completely understood, but one of the most plausible theories currently is that a high-fat diet produces high amounts of fatty acids in the intestine, which accelerate the cell proliferation. Growing evidence suggests calcium can slow this process by binding to fatty acids and bile acids.
[Washington Post.com, July 6, 1999]
Calcium And Blood Pressure – Supplementing with extra calcium might be a simple way to help bring down high blood pressure. According to a recent report published in the Journal of Human Hypertension, supplementing with about 1,000 mg of calcium each day could significantly reduce blood pressure. An isolated high blood pressure reading may not be of particular concern, but when blood pressure remains elevated over time, the risk for developing cardiovascular disease rises. Studies have shown that eating a diet rich in fruits and vegetables contributes to lower blood pressure, and that adding low-fat dairy products to this type of diet further enhances the beneficial effects.
To determine the effect of supplemental calcium on blood pressure, researchers from Holland summarised the findings of 40 different hypertensive studies, including almost 2,500 people, about one-half of whom had high blood pressure. The average length of the trials was ten weeks, during which the people took about 1,200 mg of calcium per day. Overall, calcium supplementation led to a 1.9 point drop in systolic blood pressure and a 1.0 point drop in diastolic pressure.
Insufficient calcium intake, poor calcium absorption, and/or excessive calcium losses through the urine and faeces can cause calcium deficiency.
Rickets is a condition characterised by bone deformities and growth retardation which may develop in children who are calcium deficient. Osteomalacia is a condition which may develop in adults due to insufficient calcium, it is characterised by”softening of the bone”. Osteoporosis is more prevalent in the Western world and also results from calcium deficiency.
Low levels of calcium in the blood (especially one particular form of calcium, called free ionised calcium) may cause a condition called tetany, in which nerve activity becomes excessive. Symptoms of tetany include muscle pain and spasms, as well as tingling and/or numbness in the hands and feet.
In general, you can take calcium supplements at any time during the day. But there are several factors to consider that may affect the timing of taking calcium supplements, including how much you take, other medications you may take and the form of calcium supplement you take (check the product label).
The following medications and nutrients may impact the absorption, digestion, utilisation and excretion of calcium:
In general, a large dose of any single mineral such as calcium may cause deficiencies or imbalances of other minerals. Individual mineral supplements should therefore usually be balanced by a multiple mineral supplement. This is important particularly with other minerals such as copper and zinc, which literally compete with one another for absorption.
Calcium is probably the most commonly self-prescribed macro mineral, apart from magnesium. I don’t often find that a person will take a cal/mag supplement, but rather supplement calcium or magnesium on their own. In fact, they would be better off taking a balanced calcium/magnesium supplement.
Calcium can be purchased in many forms, in fact there are over 35 different forms of calcium on the market, making selection very confusing for those who want to supplement with calcium. These forms vary in the amount of calcium they contain and also vary in the rate of absorption and bio-availability. The two most common supplemental forms however are calcium carbonate and calcium citrate. The low cost makes calcium carbonate a common choice for formulating products.
There are generally three supplementary forms of calcium available:
Dairy products do contain just about the highest dietary sources of calcium, but I do appreciate that not everybody can tolerate them.
Dairy products – The most commonly known high calcium foods are the dairy foods, and the best choices here are yogurt, mozzarella cheese, cow and goat’s milk. Some people avoid dairy in the belief that they may have a dairy allergy. You may want to be absolutely certain here, because dairy foods are some of the highest calcium containing foods.
A combination of a “no dairy” diet and advancing age along with hypochlorhydria (under-function stomach and/or lack of sufficient hydrochloric acid & digestive enzymes) is a sure fire recipe for osteoporosis. But, contrary to what the dairy industry tells us, milk consumption may not lead to strong bones after all. While there are numerous clinical studies demonstrating that calcium supplementation can retard bone loss, the data really is inconclusive regarding a high dietary calcium intake from milk for the prevention of osteoporosis fractures.
One of the most enlightening clues that milk consumption may not be beneficial for bone health is data showing that countries with the highest dairy intake also have the highest rates of hip fracture (and osteoporosis) per capita.
Data from a nurses health study involving nearly 80 thousand women, gave an outcome showing no evidence that a higher intake of milk reduced fracture incidence. The most telling facts to come out of this study were that women who drank two or more glasses of milk per day had a relative risk of 45% for hip fracture, compared to women consuming one glass or less per week. My advice? – consume your calcium from a wide variety of food sources, and I recommend yogurt as the best dairy calcium source because you get the beneficial bacteria and lactic acid as well as the calcium. Try my home-made yogurt recipe.
Green leafy vegetables – There are many reasons to eat your leafy greens, and here is one of the most important reasons: Did you know that green vegetables are an excellent source of not only magnesium, but calcium as well? Most green leafy vegetables contain minerals such as potassium, magnesium and calcium, but Swiss chard (silver beet), turnip greens, kale, broccoli, Brussels sprouts, asparagus and Chinese vegetables such as Bok choy and mustard greens are some the best. Other good calcium containing greens are celery, romaine lettuce, The best seaweeds are kombu and kelp.
Nuts and seeds – Sesame seeds top the list. Try making Gomashio Japanese Condiment, it is a delicious condiment rich in calcium which is a perfect topping for your steamed broccoli, also rich in calcium. Try making a trail mix using sesame seeds, pumpkin and sunflower seeds and nuts to give your calcium and magnesium intake a healthy boost.
Too much calcium (more than 3,000 mg per day) may result in elevated blood calcium levels, a condition known as hypercalcemia. Soft tissue calcification may occur if calcium levels remain high and phosphorus levels remain too low at the same time. Soft tissue calcification can cause the unwanted deposition and accumulation of calcium in different parts of the body. For this reason, you need to take care with calcium supplementation.
In 2010 the National Academy of Sciences established a revised Tolerable Upper Intake Levels (ULs) for calcium as follows: