Why calcium is good for you

Calcium is the most abundant mineral in the body. About 98% of the calcium in the body is in the bones, while another 1% is in teeth and the other 1% circulates in the blood. Calcium is required all through life to keep bones and teeth strong and healthy.

The calcium in blood has very useful and important functions to perform, so much so that the body will pull calcium from the bones to make sure there is enough in the blood.

Calcium in the blood helps regulate heartbeat, controls blood pressure, clots blood, contracts muscles and sends messages along nerves. Calcium is also required to make certain hormones and enzymes, especially the ones that control digestion, how energy is made and fats are used. It also helps build connective tissues.

Bones, while hard, are actually living tissue. Old bone is constantly being broken down and replaced with new bone at a specific rate until the age of about 35. After that age, the rate that new bone can replace old bone decreases and saved up bone is drawn upon. Some slow bone loss is a normal part of aging, but if not enough calcium is taken in, the process can happen too fast, especially in women who have reached menopause. If too much bone is lost and there is not enough calcium to help replace the old bone with new, bones become thin, brittle and break very easily. This is called osteoporosis

If the bones are strong to begin with and plenty of calcium in foods (or supplements) are taken in all through a person’s life, the bones will stay strong throughout life. Even if osteoporosis has already set in, calcium may help slow it down.

Important calcium facts

• Calcium is the most abundant mineral in the body
• Calcium works with vitamin D to keep the blood levels of calcium normal. Vitamin D is required to help bones hold onto their calcium.
• Magnesium helps to body absorb calcium and vitamin D properly. The basic rule is: ½ as much magnesium as calcium
• Since the body needs to use calcium 24 hours a day, it is best to space out calcium over the day and have calcium-rich foods with every meal
• To help build stronger bones and teeth, calcium needs to work together with magnesium, boron, vitamin D and phosphorus to create healthy bone tissue
• In order for the levels of calcium and magnesium to be at the correct levels and ensure health is maintained, the ratio of calcium to magnesium should be 2:1
• Calcium are better absorbed with some dairy, such as a few spoonfuls of yoghurt, some milk, a piece of cheese. This helps to ensure the stomach produces enough acid to break down the supplement to be able to absorb the calcium in it
• Don’t take calcium supplements on an empty stomach or with other foods, as they wont be absorbed as well
• Calcium is required to make sure all the body’s muscles contract properly and all nerve impulse fire off correctly to enable them to send messages through the nervous tissues to all areas of the body
• If there is a vitamin D deficiency, it could lead to a calcium deficiency, as vitamin D helps the body absorb calcium and if there is insufficient vitamin D intake in the diet, it could lead to a calcium deficiency and bone loss
• Calcium is needed to activate enzymes responsible for the digestion of fats and proteins, as well as in enzymes that help to produce energy for the body
• Calcium helps to build connective tissues, which helps to keep the body together.
• Osteoporosis affects many people, especially women after menopause, when their oestrogen levels go down and is very costly for the health system

Calcium works best with

• Vitamin A
• Vitamin C
• Vitamin D
• Vitamin K
• Arginine
• Carnosine
• Lysine
• Magnesium
• Boron

Calcium and health

• Heart disease – two important studies showed a link between atherosclerosis and osteoporosis. In the first study, researchers found that women who had the most bone loss from osteoporosis were also most likely to have calcium-containing plaque blocking their carotid arteries. Because the carotid arteries carry blood to the brain, these women were at a higher risk of having a stroke. The second study showed that men and women with low vitamin D levels also had higher rates of calcium-containing plaque in the arteries leading to their hearts, making them more vulnerable to heart attacks. More follow-up research is being done, but these studies show how important calcium is for every aspect of long-term health
• High blood pressure – calcium may help prevent or treat high blood pressure in some people. People not getting enough calcium in their diet are more likely to get high blood pressure than people who get the RDA or more. In general, the higher level of calcium in the blood, the lower the blood pressure. Studies show that taking calcium supplements each day, can lower blood pressure for some people. People with high blood pressure should talk to a medical professional about calcium supplements BEFORE taking them, especially if taking any other prescription drugs
• Low calcium intake in childhood leads to rickets
  Insufficient calcium intake in childhood leads to the disease rickets, where the bones (and teeth) become too soft and deformed, growth is stunted and the skull is not formed properly. Rickets is entirely preventable and rarely occurs in developed nations where foods rich in calcium are in abundant supply. It is more of a problem in countries where there is famine.
• Calcium helps to prevent osteoporosis
  Calcium is one of the most important minerals that is needed by the body to help prevent osteoporosis – a disease which causes a break-down in the bone tissue matrix by a lack of calcium and which causes the bones to be very brittle and break easily.
• Calcium is vital for the parathyroid and thyroid glands to work properly
  The thyroid and parathyroid glands rely on a specific (but very small) amount of calcium to function properly and if these levels are disturbed, then either or both these glands can malfunction. When blood calcium levels are too low, the parathyroid hormones release parathyroid hormone (PTH), which stimulates the break down of bone tissue to release enough calcium into the blood (this means that there is a decrease in any new bone tissue formation). The release of PTH also stimulates increased activation of vitamin D and decreased excretion and increased intestinal absorption of calcium and magnesium. This has huge implications on bone tissue loss and osteoporosis. Conversely, if there is too much calcium in the blood, the thyroid gland releases the hormone calcitonin, which stimulates the bone cells to increase new bone tissue formation and to stop any break-down of bone tissue.
• Calcium regulates the heartbeat, ensuring it beats regularly
  Calcium, along with magnesium, is vital for ensuring the heart beats properly and regularly. Calcium regulates the way that the heart muscle cells contract and then relaxes in each heartbeat. The strength of heartbeat depends entirely on the amount of calcium released and the cell’s sensitivity to the calcium.
• Calcium is vital for ensuring healthy blood pressure levels
  Many recent studies show that high blood pressure (hypertension) could be a result of low dietary calcium intake together with a high dietary sodium intake. The studies showed that both men and women who were given a calcium supplement had a dramatic reduction in blood pressure (back to normal levels), which was similar or better than the reduction achieved with conventional blood pressure medication and that the people with hypertension who were most sensitive to the blood pressure elevating effects of salt has the most benefit.  In addition, other studies show that there is a definite correlation between pregnant women who had high blood pressure (a major risk factor for pre-eclampsia, a condition which poses a risk for the mother and baby’s lives) and a low calcium dietary intake.
• Calcium helps prevent heart disease
  Two important studies have shown a link between atherosclerosis and osteoporosis. In one study, it was determined that women who had osteoporosis were more likely to have calcium-containing plaque blocking their carotid arteries (these are the arteries that lead to the brain) and thus bring a higher risk for stroke. The other study showed that both men and women how had low levels of vitamin D also had higher rates of calcium-containing plaque in the arteries leading to the hearts, which has a higher risk of heart attack.
• Enables the blood to coagulate properly when required
  Sufficient calcium is required to enable the blood to coagulate (or clot) properly when any of the body tissues are damaged, to help heal and repair the tissues more quickly.
• Calcium is needed to maintain cell membrane elasticity and general cell health
  Calcium helps to maintain and restore a normal electric cell potential between both sides of the cell membrane. Calcium is also effective in transporting essential minerals through the cell membrane wall and into the cell. In these important ways, calcium is vital in maintaining the health of cell membranes, without which leaves the cells open to attack by undesirable chemicals and toxins and can cause or contribute to a wide range of diseases. Calcium regulates of both cell death and the mechanisms underlying cell proliferation, which can become defective and cause cancer. Research has shown that the various characteristics of calcium signalling in the cell ultimately determining the cell’s fate.

People who wish to take a calcium supplement should talk to a medical professional before taking it.

Current research

• Calcium may be implicated in Alzheimer’s Disease
  Recent research suggests that a disruption of the calcium in synapses of neurones (the endings of nerves that send the messages to other nerves) could cause the impairment in nerve signalling, thus causing cognitive defects, which are part of the initial symptoms of Alzheimer’s Disease.
• Calcium may reduce incidence of colon cancer
  Recent research shows that people who get enough vitamin D from sunshine and enough calcium from dairy foods, have a reduced incidence of colon cancer and that those people who had colon cancer and had a low calcium had a higher chance of dying from the cancer than the people who had a higher calcium intake. Another study showed that people with colon cancer who were supplemented with calcium, had a significant decrease in the number of cancer cells in the lining of the colon after about the second month of supplementation. Promising research shows that the lower that calcium intake is, the more likelihood to develop colon cancer, possibly because calcium blocks the growth of cancer cells.
• Calcium may be implicated in muscular dystrophy disease
  Recent research shows that there is a correlation between misregulation of calcium levels and underlying cellular activity and pathogenesis of Duchenne muscular dystrophy (DMD). Further research is going on in this area to determine the exact cause and how misregulation of calcium interferes with proper muscle activity, with a view on how to prevent muscular dystrophy.

People in these groups who wish to take a calcium supplement should talk to a medical professional about it.

Groups at risk of calcium deficiency

Over half of all young people today (especially women) do not get the recommended daily intake of calcium in their diet, probably because they do not eat enough foods rich in calcium.

Calcium deficiency occurs when there is less than 200mg intake of calcium from foods per day.

The following groups are most at risk of deficiency:

• People taking corticosteroid drugs
  Medicines such as cortisone, hydrocortisone, prednisone and dexamethasone, used by people with asthma, lupus, rheumatoid arthritis, inflammatory bowel disease and other medical problems, while they are lifesavers for people with these conditions, can also cause bone loss by breaking down bone faster than it can be replaced. Doctors previously thought that glucocorticoid drugs only caused problems with bone loss if taken in high doses, but recent research shows that taking consistent amounts of these drugs for long periods of time also cause bone loss. Talk to a medical professional about having a bone density test and about taking calcium and vitamin D supplements
• People taking thyroid drugs
  Large doses of thyroid drugs (eg Synthroid) over a long period can lead to bone loss
• People taking cholesterol-lowering drugs
  People taking cholesterol lowering medications are at risk of calcium deficiency because these types of medications cause bone loss by breaking down bone faster than it can be replaced. These drugs (eg Cholybar, Questran) can block absorption of calcium and fat-soluble vitamins such as vitamin D and vitamin A
• People with a lactose intolerance
  People who are lactose intolerant, may not be eating enough non-dairy calcium-rich foods to get enough calcium in their diet, due to their condition
• People taking aluminium antacids
  Non-prescription antacids that contain aluminium (eg Maalox, Rolaids, Gelusil) can cause the body to store up aluminium in the bones instead of calcium. This could create weakened bones, especially in people with kidney problems. If these antacids are not used regularly, then it is not a major concern, but people taking these antacids regularly for heartburn should talk to a medical professional about other ways to control it
• Smokers and alcoholics
  Heavy drinkers and smokers have a higher risk for osteoporosis and those that do both are at an even greater risk. Smokers seem to have a lower bone density than non-smokers (it is a not yet known why), so that is a risk factor in itself. A recent study showed that smoking doubles the risk of hip fractures, even if osteoporosis is not present. Alcohol interferes with absorption of calcium and heavy drinkers often do not eat well and do not get enough calcium in their food
• People taking certain prescription drugs
  Certain drugs, while valuable therapies for specific health problems, can sometimes interfere with and block calcium absorption. Some prescription drugs do not mix well with calcium supplements and can cause adverse problems if taken together or even hours apart. It is important to consult a medical professional if you are taking ANY prescription drugs and want to try calcium
• People on a high protein diet
  People who are on a higher protein diet, may need more calcium in their diet than people who eat less protein (or predominantly eat a vegetarian diet), this is due to the amount of natural phosphates in vegetables and ensuring the correct calcium/phosphorus ratios in he body.
• Post-menopausal women
  Women who have been through menopause are at greater risk of osteoporosis due to the decreased levels of oestrogen in their body (oestrogen has a protective effect on the heart and also ensures adequate uptake of calcium into the bones)

People in these groups at risk of deficiency should talk to a medical professional about calcium supplements before trying them.

Symptoms of calcium deficiency

Calcium deficiency occurs when intake of calcium in the diet is less than 200mg per day. Low levels of calcium can cause the following deficiency symptoms:

• Osteoporosis
  Osteoporosis is a disease which causes a break-down in the bone tissue matrix by a lack of calcium. This breakdown causes the bones to be very brittle and break easily.
• Osteoarthritis
  Low levels of calcium intake in the diet are implicated in the health condition osteoarthritis (while this condition does have other risk factors, low levels of calcium is the most common reason why it occurs).
• Rickets
  Insufficient calcium intake in childhood leads to the disease rickets, where the bones (and teeth) become too soft and deformed, growth is stunted and the skull is not formed properly. Rickets is an entirely preventable calcium deficiency health condition.
• Soft, yellow teeth
  Another symptoms of calcium deficiency is when the teeth start to become more yellow (less white) and so the teeth can get softer and be predisposed to tooth decay.
• Muscle cramps
  Muscle cramping in the legs are early sign of calcium deficiency. The cramps generally occur at night.
• Dry skin and brittle nails
  Another common calcium deficiency symptom is dry skin and brittle nails that break easily.

Calcium in food

Calcium recommended daily intake (RDI)

The tolerable upper limits should only be taken for short periods and only under medical supervision.

* The tolerable upper limit for calcium for infants aged 0-12 months has not yet been determined due to a lack of data about the adverse effects in this age group. The only source of calcium intake should be from food (breast milk and/or baby formula).

Toxicity

Calcium is generally non-toxic. Large amounts over 5,000mg (5g) may increase the requirement for magnesium.

Symptoms of toxicity

Too much calcium from supplements is not advisable, as it can cause a whole range of ill effects from overdosage:

• Asthma
• Depression
• Gall stones
• Hypercalcaemia (high blood levels of calcium)
• Imbalance of calcium/phosphorus ratio
• Kidney stones
• Memory impairment
• Muscle weakness
• Spurs
• Thyroid gland imbalance (hyperparathyroid)
• Vitamin K malabsorption

If the calcium to potassium ratio is >2:1, this can result in reduced bone strength and interference with vitamin K synthesis and/or absorption. Amounts > 2grams may cause hyperparathyroidism.

People experiencing any of the above toxicity symptoms should discontinue their calcium supplements and seek medical advice.

Overdosage and toxicity is more likely to occur from taking too many supplements, whereas dietary intake of calcium is highly unlikely to cause overdosage.

Precautions

In general, calcium supplements produce no major problems for otherwise healthy individuals, but certain people should not take calcium supplements without first consulting their doctor for advice:

• People with kidney or liver disease
• People with any type of medical condition

People taking any type of medication should talk to a medical professional about calcium supplements before taking them.

Interactions with medications and supplements

Calcium has detrimental interactions with the following medications and supplements:

• Calcibind
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• Cellulose sodium phosphate
  Cellulose sodium phosphate medications are used to prevent kidney stones. When calcium supplements are taken at the same time as these medications, it can decrease the effect of the medication and cause the kidney stones to continue to be formed.
• Digitalis
  Digitalis medications are used to prevent congestive heart failure and some types of heart arrhythmias (irregular heart beats). When calcium supplements are taken at the same time, they can cause further irregular heartbeats and decrease the function of the digitalis medication.
• Etidronate
  Etidronate medications are used to prevent osteoporosis (and other bone thinning conditions). When calcium supplements are taken at the same time, they decrease the effects of the medication. Etidronate medications should be taken at least 2 hours after taking any calcium supplements to prevent any decrease of the medication’s effects.
• Gallium nitrate
  Gallium nitrate is used to treat high calcium blood levels (hypercalcaemia) that may occur with cancer. Calcium supplements should not be used if this medication is prescribed as it will inactivate the function of the medication and continue to cause high calcium blood levels.
• Iron supplements
  Iron supplements are used to treat iron-deficient anaemia. Calcium supplements can decrease the absorption of the iron supplements if they are taken at the same time, unless vitamin C supplements are taken at the same time as the iron supplements. Even foods high in calcium can cause an absorption problem if they are taken at the same time as iron supplements (unless vitamin C is also taken).
• Oral contraceptives and oestrogen
  Oral contraceptives and oestrogen medications are used as contraceptives in premenopausal women and for reducing symptoms on menopausal women. If calcium supplements are taken at the same time, the medication can cause an increased calcium absorption.
• Phenytoin
  Phenytoin medications are used to prevent and manage seizures in people with epilepsy. If calcium supplements are taken at the same time, it can cause a decreased effect of both the phenytoin medication and also the calcium. It is advisable not to take calcium supplements within 1-3 hours of taking the phenytoin medications.
• Tetracyclines (oral)
  Tetracyclines (oral) are antibiotics used to treat a variety of bacterial infections. If calcium supplements are taken at the same time as the tetracycline medication it can cause a reduction in the absorption of the tetracycline and nullify its effect.

Calcium has beneficial interactions with the following medications and supplements:

• Magnesium-containing medications or supplements
  Magnesium-containing medications or supplements are used for a variety of reasons, but mainly to relax the muscles. Calcium supplements taken at the same time as the medications will increase the absorption of magnesium and calcium in the body (from food or supplements).
• Vitamin D
  Vitamin D supplements are used to help with calcium absorption, especially in people with osteoporosis or risk of developing it. If calcium supplements are taken at the same time, the vitamin D can help the calcium be better absorbed.

Calcium’s effect on lab tests

Calcium has an effect on the following lab tests:

• Serum hydroxycorticosteroid
  Serum (blood) concentrations of hydroxycorticosteroid can be elevated when calcium supplements are taken over a long time and at high levels. These class of medication deplete calcium levels in the body
• Serum phosphate (phosphorus)
  Serum (blood) concentrations of phosphate (phosphorus) may be reduced when calcium supplements are taken over a long time and at high levels.

Other interactions with calcium

Calcium also has interactions with the following substances:

• Alcohol
  Alcohol can decrease the absorption and increase the elimination of calcium, so it could cause a deficiency that will require supplementation if the alcohol intake is excessive and over a long term.
• Caffeine
  High intake of caffeine (from coffee, tea, soft drinks and chocolate) can reduce absorption of calcium, so eat foods high in calcium (or take calcium supplements) at least an hour or so before having any caffeine containing drinks or food.

References

• USDA National Nutrient Database – provides nutrient values for foods (accessed 5 January 2005)
• Osiecki, H. The Nutrient Bible. Bio-Concepts Publishing QLD, 2002
• Whitney EN, Cataldo DB, Rolfes SR. Understanding Normal and Clinical Nutrition, 6th Edition. Wadsworth/Thomson Learning, 2002

Last updated: 6 May 2024