FREE Shipping on Canadian Orders Over $200

Calcium and Magnesium - Facts and Fallacies


 By Zoltan P. Rona, M.D., M.Sc. 


Calcium and Heart Attacks

 Do calcium supplements really cause heart attacks? A recent randomized controlled trial published in the January edition of the British Medical Journal (15 January 2008) concludes that  

"Loading with high doses of calcium reduces bone loss but at a cost in heart health that is not justified." 


 According to researchers Dr. Ian Reid and his colleagues, the risk of a heart attack, stroke and sudden death is about 1.5 times greater for those who supplement with calcium.


 How can this be true?  Like other nutrients, calcium is interdependent on numerous other factors including the levels of vitamins, other minerals, hormones, the health of the digestive system and the degree of physical activity.  To make a simple pronouncement based on one factor, namely calcium supplementation, without looking at the numerous other variables in calcium biochemistry and nutrition can only lead to erroneous conclusions.  


Sure, it’s possible that calcium supplements without a proper diet, enough physical activity and in the presence of magnesium and vitamin D deficiency leads to heart disease.  But, does this mean that all middle-aged women should stop taking calcium supplements?  I think not.




Calcium is the most abundant mineral in the body.


Calcium is 1.5 - 2% of our body weight.


98% of all calcium is found in our bones, 1% in our teeth and 1% in other tissues


Calcium requires many other minerals for healthy bone formation: magnesium, boron, manganese, zinc, copper, silicon, strontium and phosphorus.


Calcium requires vitamins A, C, D and K for optimal metabolism.


Calcium absorption becomes less efficient with age.


Aside from osteoporosis, calcium deficiency can cause kidney stones and allows the body to accumulate lead.


High animal protein (very high in phosphorus) intakes may increase calcium loss through the intestines and kidneys.


A very high fat intake also inhibits calcium absorption.


Hydrochloric acid helps calcium absorption in the duodenum where most calcium is absorbed.


Antacids and prescription acid suppressing drugs all reduce calcium absorption.


Stress can lower calcium absorption.


Excess sugar and salt intake leads to calcium loss in the urine.


Phytic acid (phytates) found in whole grain foods or foods rich in fiber may reduce the absorption of calcium and other minerals as well.


Foods high in oxalic acid (spinach, rhubarb, chard, and chocolate) can interfere with calcium absorption by forming insoluble salts in the gut.


30-80% of all calcium consumed is not absorbed due to all the above factors.


Overactive thyroid function can cause calcium loss from bone.




When a person absorbs calcium, regardless of the amount, there is no guarantee that this same calcium will be deposited into the bones.  


Calcium tends to gravitate towards areas of injury in the body.  If the lining of the arteries is damaged, calcium deposits there and causes hardening of the arteries. This could make cardiovascular disease worse.  If the kidneys are damaged, the result of calcium deposition could be kidney stones.  Calcium also tends to deposit in other soft tissue injured areas like tendons and ligaments causing stiffness or other disability.


Several studies in the past decade have shown that EFAs (Essential Fatty Acids) when combined with calcium can ensure that calcium deposition will take place in bone and not in the arteries, the kidneys or other soft tissues. EFAs enhance the effects of vitamin D in the gut and improve calcium absorption from the small intestine, reduce the urinary excretion (loss) of calcium, increase calcium that is deposited in the bone and improve the strength of bone.


The dosage required for evening primrose to do this in both men and women is between 1500 – 6000 mg. daily.  Of course, calcium deposition also depends to variable degrees to the frequency of weight bearing exercises as well as the presence of minerals such as magnesium, zinc, copper, strontium, silicon, manganese and boron.  If your calcium supplement does not contain evening primrose oil, make sure you take an extra 1500 – 6000 mg. of this omega-6 source of essential fatty acids each day to prevent or reverse osteoporosis with much greater assurance.




Calcium toxicity can be a very complex issue and is not simply a question of the dose that one consumes. Virtually any amount of calcium supplementation can be toxic (soft tissue calcification, hardening of the arteries and kidney stones) in the presence of parathyroid disease, magnesium and vitamin D deficiency.  In fact, given the proper conditions, calcium deposits can occur in the arteries or kidneys with daily calcium intakes below the RDA. It all depends on the individual’s nutritional and general health status at the time.  


Through the actions of the parathyroid hormones PTH and calcitonin, the body attempts to keep blood levels of calcium within a certain normal range.  The adrenal glands, the thyroid, the small intestines, the liver and kidneys can all modify whether or not calcium absorbs, stays or comes out of the bones.  


Calcium status is also strongly influenced by the levels of vitamin D, vitamin K, phosphorus, magnesium, boron, strontium, manganese, zinc, silicon and copper. High blood levels of calcium leading to soft tissue calcification will occur with both severe deficiency as well as excessive calcium intake.



Calcium deficiency or very low blood levels of calcium can cause a wide range of symptoms including anxiety, hyperactivity, headaches, irritability, muscle cramps or spasms, numbness and tingling in the hands or feet, palpitations, insomnia, confusion and even depression.  Drinking soft water (distilled, reverse osmosis or calcium deficient water) increases the risk of cardiovascular disease. This is something that has been documented for over 100 years.  In other words, a lack of dietary or supplemental calcium causes heart disease.


Calcium Sources


Food                                Portion                   Calcium (mgs.)

 Swiss cheese              2 oz.                           530

 Jack cheese                2 oz.                           420

 Cheddar cheese        2 oz                            400

 Other cheeses            2 oz.                           300–400

Yogurt                           6 oz.                            300

 Broccoli, cooked        2 stalks                       250

 Sardines (w/bones)   2 oz.                            240

Goat milk                      6 oz.                            240

 Cow’s milk                   6 oz.                           225

 Collard greens, cooked 6 oz.                        25

 Turnip greens, cooked 6 oz.                        220

 Almonds                          3 oz.                       210

 Brazil nuts                       3 oz.                       160

 Soybeans, cooked         6 oz.                      150

 Molasses, blackstrap    1 Tbl.                     130

 Corn tortillas (4, w/lime)2 oz.                     125

 Carob flour                      2 oz.                     110

 Tofu                                  3 oz.                     110

 Dried figs                        3 oz.                     100

 Dried apricots                3 oz                      .80

 Parsley                          1½ oz.                    80

 Kelp                                 ¼ oz                     .80

 sunflower seeds            2 oz.                     80

 Sesame seeds               2 oz.                     75


 Adequate Intake (AI) for Calcium


Life Stage                        Age                              Males (mg/day)                         Females (mg/day) 

Infants                              0-6 months                   210                                                 210 

Infants                              7-12 months                 270                                                 270 

Children                           1-3 years                      500                                                 500 

Children                           4-8 years                      800                                                 800 

Children                           9-13 years                   1,300                                              1,300 

Adolescents                    14-18 years                 1,300                                              1,300 

Adults                                19-50 years                1,000                                              1,000 

Adults                                51 years and older    1,200                                              1,200 

Pregnancy                        18 years and younge   -                                                    1,300 

Pregnancy                        19 years and older        -                                                   1,000 

Breast-feeding                 18 years and younger  -                                                    1,300 

Breast-feeding                 19 years and older       -                                                     1,000


Tolerable Upper Intake Level (UL) for Calcium


Age Group                                           UL (mg/day)

Infants 0-12 months                           Not possible to establish*

Children 1-13 years                            2,500

Adolescents 14-18 years                   2,500

Adults 19 years and older                 2,500


Dairy Dithering


While North Americans have the highest intake of dairy products in the world, they also have the highest incidence of osteoporosis.  Cow’s milk has been linked to numerous digestive disorders including constipation, lactose intolerance, casein (milk protein) allergy, irritable bowel syndrome, colitis, and a long list of allergic and autoimmune disorders including juvenile onset diabetes mellitus. The good news is that there are many healthy calcium alternatives to dairy products.  Although cow’s milk has the highest calcium content, many studies demonstrate that absorption is inferior to that seen with calcium from plant sources.  


Dark green leafy vegetables have relatively high calcium concentrations. With the exception of spinach, due to the high oxalate content, the calcium from greens is very well absorbed.  Kale and other members of the same food family such as broccoli, turnip greens, Brussels sprouts, collard greens and mustard greens are also excellent sources of magnesium, a trace mineral that is important for calcium utilization and which is found in only small amounts in cow’s milk.  In the past few years, a large number of excellent whole food supplements high in both calcium and magnesium have come out on the market.  These include spirulina, chlorella, barley green, green kamut, blue green algae and several others.  These all make ideal supplements for children because they are easy to mix with juices, are highly bioavailable, easily absorbed and have a very healthy balance of dozens of trace minerals, antioxidants, vitamins, amino acids and essential fatty acids.


Other natural sources of calcium include cooked beans and peas, seaweeds, soy products like tofu and soy milk, sprouts (e.g. alfalfa), seeds and nuts like sesame, pumpkin and hazelnuts as well as whole grains (e.g. corn tortillas, quinoa). 


Best Calcium Supplements and Worst Calcium Supplements 


Whatever the calcium supplement, make sure it is balanced by at least half the amount of magnesium and that vitamin D levels in your system are adequate. Many health experts recommend a 1:1 ratio of calcium to magnesium in a supplement but this is not something cast in stone (or, dolomite, if you prefer).


If a calcium supplement is giving you constipation, just up the dose of the magnesium you take with it to where your bowels are moving well enough to your liking.  Ideally, get biochemical tests for the levels of all these nutrients before engaging in any aggressive supplementation.


Since many people are unable to follow a diet with an acceptable calcium intake, have digestive problems, food allergies that prevent calcium absorption and a long list of other special situations already enumerated, calcium supplements can become a necessity.  


Studies indicate that calcium carbonate, the most widely used calcium supplement, is suitable for most people.  While other forms of calcium like calcium citrate, fumarate, gluconate, lactate, malate, orotate, succinate and aspartate may be better absorbed, the disadvantages of using the carbonate forms can be overcome by taking the supplement with food or something that acidifies the duodenal contents (e.g. betaine hydrochloride, apple cider vinegar or citrus juice).  The big advantage of calcium carbonate is that it is inexpensive and requires fewer capsules or tablets to obtain equivalent amounts of elemental (pure) calcium.


Microcrystalline calcium hydroxyapatite, a hyper-hyped form of calcium supplementation provides no advantage over calcium carbonate, is more expensive and is the poorest absorbed of all the supplemental forms of calcium.


Coral calcium, another of the over-hyped calcium supplements, has been found to contain traces of lead and other toxic impurities.  Like oyster shell calcium, dolomite and bone meal, coral calcium is nothing more than calcium carbonate plus lead and other poisons.  None of these are recommended.


Calcium bound to Krebs Cycle intermediates (citrate, lactate, aspartate, gluconate, malate, etc.) have the decided advantage of being better absorbed from the gastrointestinal tract than calcium carbonate, even in the absence of adequate stomach and duodenal acidity.  The problem with all of them is the expense and the fact that they are all bulkier molecules requiring more capsules or tablets to achieve the same dosage as calcium carbonate.


Some supplements contain calcium phosphate, which is very poorly absorbed and can block the absorption of iron and other trace minerals.  Calcium phosphate is the most constipating of all the calcium supplements and should be avoided.


Dumb and Dumber Studies


Every year, without exception, we see counter-intuitive studies concluding nonsense like “calcium supplements cause heart attacks” or “vitamin C causes DNA damage” or “beta carotene causes cancer” or “vitamin E causes phlebitis”.  The public panics, throws the vitamin and mineral supplements into the garbage and heads for the Aspirin and Lipitor bottles.  


Examine any of these not so brilliant studies closely enough and you discover that the research was conducted in a test tube as opposed to a human or that smokers taking prescription cholesterol lowering drugs were used in the study or that synthetic inactive forms of a vitamin were used.  If a study sounds too weird to be true, it’s probably not true.  


In this study on calcium supplements there was no mention of magnesium or vitamin D blood levels, dietary animal protein intakes or any of at least a dozen factors influencing calcium metabolism. There is therefore no evidence that calcium supplements taken as part of a balanced nutritional program of diet and vitamin and mineral supplements leads to heart attacks.  If you are still not convinced, see a natural health care practitioner who can sort out what’s high or low in your body so that the appropriate adjustments can be made to get you into balance.


Calcium is the mineral that has always had the most media attention as well as the overwhelming approval of the medical profession as a supplement that women should be taking.  That in itself may be enough to arouse suspicion.  As you might suspect, there are other more important minerals to consider for optimal health.   For example, despite a great deal of published medical and biochemical research, there is little, if any, attention paid to calcium’s neglected cousin, magnesium and most certainly no medical pronouncements that anyone should be supplementing this mineral in any serious way.  Its under-utilization in clinical medicine is nothing short of scandalous, especially in its use as a life-saving cardiovascular tonic.


Magnesium Facts and Figures 


Magnesium appears by many names.  Below is a list of how you might see it in health food stores and pharmacies: 


Chelated Magnesium, Dolomite, Epsom Salts, Magnesia, Magnesium Aspartate, Magnesium Carbonate, Magnesium Chloride, Magnesium Citrate, Magnesium Disuccinate Hydrate, Magnesium Gluconate, Magnesium Glycerophosphate, Magnesium Glycinate, Magnesium Hydroxide, Magnesium Lactate, Magnesium Malate, Magnesium Murakab, Magnesium Orotate, Magnesium Oxide, Magnesium Phosphate, Magnesium Sulfate, Magnesium Trisilicate, Milk of Magnesia.

the second most plentiful cation (positive ion) in the intracellular (inside cells) fluid and the most plentiful cation in the body 

involved with more than 300 enzyme systems; plays an essential role in more than 300 cellular reactions

the body contains about 25 grams of magnesium, divided equally between the skeleton and soft tissue 

extracellular (outside cells) magnesium makes up only 1% of total body magnesium 

absorbed throughout the gastrointestinal tract, although whether maximal absorption occurs in the duodenum or colon is unclear

about one third of dietary magnesium is absorbed with efficiency of absorption depending on magnesium stores in the body, among other factors. 

average absorption of supplements is 38%, but varies from 65% in people with low magnesium stores to 11% with high magnesium stores

excreted mainly through the kidneys

is important for normal bone structure

required for the formation of cyclic AMP (cAMP) and is involved in ion movements across cell membranes

requires both parathyroid hormone and vitamin D for absorption


Sources and Bioavailability of Magnesium 


Magnesium is well absorbed from food sources such as legumes, whole grains, vegetables (especially broccoli, squash, and green leafy vegetables), seeds, and nuts (especially almonds). Magnesium is the central element of chlorophyll, the substance that gives plants their green colour.  Hence, if it’s green, consider the food as a potentially good magnesium source.


Water with a high mineral content, or "hard" water, is also a source of magnesium. So-called “soft water” (e.g. distilled or reverse osmosis water) is not only void of magnesium but may actually promote its loss from the body.


Absorption of magnesium from supplements (i.e. bioavailability) varies. Magnesium chloride, magnesium lactate and magnesium aspartate appear to be most bioavailable. Magnesium oxide and magnesium sulfate have bioavailability only of about 4%. Enteric coating of some magnesium products may reduce the absorption of magnesium.


Magnesium Deficiency Effects


Magnesium deficiency is not uncommon in North America, especially among African Americans and the elderly. Low intake and impaired absorption of magnesium are associated with osteoporosis, hypertension, atherosclerotic vascular disease, cardiomyopathy, diabetes, and stroke.


Serum magnesium levels are depressed only in cases of severe magnesium deficiency and it poorly correlates with body magnesium). The body preserves serum magnesium at the expense of magnesium in cells and bone, so serum levels may appear normal in magnesium deficiency. Red cell and urine magnesium levels are also poor indicators of body magnesium). The intravenous magnesium loading test is considered to be a more reliable test to measure magnesium status but the test is cumbersome and is known for poor patient compliance. 


Free ionic magnesium levels have been shown to vary with many disorders such as cardiac disease, stroke, diabetes, and migraines but measurement of ionized magnesium may not be readily available in labs outside the research setting. 


Since magnesium is an anti-spasmodic or relaxant, one expects and sees symptoms of severe magnesium deficiency to include convulsions, confusion, muscle weakness, abnormal muscle movements such as spasms, tremors, myoclonus, and tetany as well as arrhythmias including ventricular tachycardia, fibrillation, and something called torsades de pointes. 


Magnesium is often referred to as nature’s calcium channel blocker.  When intracellular levels of magnesium are low, this causes an increase in intracellular calcium. In addition to contributing to insulin resistance, higher intracellular calcium levels enhance calcium-mediated vasoconstriction, and inhibit cardiac and smooth muscle relaxation. The increased vascular tone can cause increased blood pressure. The pharmaceutical industry makes use of calcium channel blocking drugs to reverse this.  Practitioners in the natural health care industry use magnesium to accomplish this with fewer side effects.


Low serum magnesium is related to low-grade chronic inflammation. Magnesium deficiency is associated with elevated serum concentrations of tumor necrosis factor-alpha and C-reactive protein (CRP). People with high dietary magnesium intake have lower levels of CRP, which may reduce cardiovascular disease risk. Consuming less that the recommended dietary allowance (RDA) for magnesium is associated with a 1.48 to 1.75 times higher risk of having an elevated CRP. 


Health Enhancing Uses of Magnesium


The following list includes many very well documented uses of magnesium in health promotion:


To correct magnesium deficiency

Laxative effects (constipation and to prepare bowel for colonoscopy or surgery)


Allergic rhinitis

Cancer-associated neuropathic pain

Cardiovascular disease: angina, arrhythmias, hypertension, coronary heart disease and hyperlipidemia, low high-density lipoprotein (HDL) levels, mitral valve prolapse, vasospastic angina, myocardial infarction

Multiple sclerosis

As an antacid for symptoms of gastric hyperacidity

Attention deficit-hyperactivity disorder (ADHD)


Chronic fatigue syndrome (CFS) - in people with low red blood cell magnesium, there is some evidence that weekly intramuscular injections of 1 gram magnesium sulfate improves CFS symptoms

Lyme disease


Pregnancy-induced leg cramps

Diabetes, insulin resistance and metabolic syndrome

Kidney stones; magnesium can prevent the recurrence of especially calcium oxalate stones

Migraine headaches and cluster headaches

Neuroprotective agent in patients diagnosed with acute stroke


Post-hysterectomy pain

Premenstrual syndrome

Altitude sickness

Urinary incontinence


Restless leg syndrome

Preventing hearing loss

Paranoid schizophrenia treatment because levels appear to be lower in acute attacks of paranoid schizophrenia

By athletes to increase energy and endurance

Topically, used for treating infected skin ulcers, boils, and carbuncles; and for speeding wound healing

Stroke risk reduction in men

Topically as a cold compress in the treatment of erysipelas and as a hot compress for deep-seated skin infections

Intravenously (IV) or intramuscularly (IM)  used for acute hypomagnesemia occurring in conditions such as pancreatitis, malabsorption disorders, and cirrhosis, and for treating pre-eclampsia and eclampsia (toxemia of pregnancy); considered the agent of choice for pre-eclampsia and eclampsia

As an additive to total parenteral nutrition (TPN) 

Controlling seizures (IV or IM) associated with epilepsy, glomerulonephritis, or hypothyroidism when low serum magnesium levels are present

IV or IM in the treatment of atrial and ventricular arrhythmias, for preventing arrhythmias after myocardial infarction and for cardiac arrest

IV for treating acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD), for migraine headaches, neuropathic pain and postoperative pain, as an osmotic agent for cerebral edema, and for tetanus.

Both oral and IV forms reduce the need for numerous prescription drugs


Safety Issues


Used orally, magnesium is safe when used in doses below the tolerable upper intake level (UL) of 350 mg per day. Doses greater than that frequently cause gastrointestinal irritation, nausea, vomiting, loose stools and diarrhea. Prolonged diarrhea caused by excessive magnesium intake can even cause worsening magnesium deficiency.  


Doses of 5000 mg daily have been used IV and IM without significant side effects. Intravenously, rapid infusion of magnesium can cause a flushing sensation, local pain and irritation, dizziness, bradycardia (a very slow heart rate), and low blood pressure. In children, magnesium is safe when used in doses below the tolerable upper intake level (UL) of 65 mg per day for children 1 to 3 years, 110 mg per day for children 4 to 8 years, and 350 mg per day for children older than 8 years. Higher doses can cause diarrhea and symptomatic hypermagnesemia (high blood magnesium) including hypotension, nausea, vomiting, and bradycardia (slow heart rate). Some research suggests intravenous magnesium at higher doses in pregnant women can increase fetal mortality and adversely affect neurological development. 


Although extremely rare, death is possible from excess magnesium supplementation.  There are two reports of fatal hypermagnesemia. One report involved a 28 month-old child treated with 800 mg of oral magnesium oxide per day for constipation, then given 2400 mg magnesium oxide for several days before hospital admission. Another report involved a patient who gargled with Epsom salts (almost 100% magnesium sulfate) over several weeks. The patient used an entire box two days prior to hospital admission.  Just a reminder here that deaths can occur with drinking too much spring water too.  Virtually any natural or synthetic substance can be toxic to some individual at some dose.


Supplement Interactions


Boron supplements can reduce urinary excretion of magnesium and increase serum levels in women. This may be one of the reasons why boron is effective supplementation for osteoporosis.  


Calcium supplements, when unbalanced by magnesium, can decrease the absorption of dietary magnesium, but only at very high doses (2600 mg per day). The advice here, especially for those at high risk for magnesium deficiency is to take calcium supplements at bedtime, instead of with meals, to avoid inhibiting dietary magnesium absorption. This may help explain the finding a few months ago that found that people who used high doses of calcium supplements tended to have higher rates of heart disease.  Magnesium, on the other hand, does not seem to affect calcium absorption.


If you use high doses of zinc, you might also need a magnesium supplement.  Supplementation with high doses of zinc, 142 mg/day, decreases magnesium absorption and magnesium balance in healthy adult males.  Moderately high dietary zinc intake (53 mg per day) seems to increase magnesium excretion without affecting copper metabolism in postmenopausal women. Zinc may compete with magnesium for ion exchange transport in the intestine but research on the clinical importance of these observations is needed.


Alcohol abuse increases the risk for magnesium deficiency because alcohol impairs the ability of the kidney to conserve magnesium


Drug Interactions


Neuromuscular weakness and even paralysis can occur if magnesium and aminoglycoside antibiotics are taken concurrently. The aminoglycosides include amikacin (Amikin), gentamicin (Garamycin), kanamycin (Kantrex), streptomycin, and tobramycin (Nebcin).


Magnesium can form insoluble complexes with quinolone antibiotics (ciprofloxacin (Cipro), levofloxacin (Levaquin), ofloxacin (Floxin), moxifloxacin (Avelox), gatifloxacin (Tequin), and others) and decrease their absorption. It is best to take these drugs at least 2 hours before, or 4 to 6 hours after, magnesium supplements.


Magnesium can also form insoluble complexes with tetracyclines and decrease their absorption and antibacterial activity). It’s therefore best to take these drugs at least 2 hours before, or 4 to 6 hours after, magnesium supplements. Tetracyclines include demeclocycline (Declomycin), doxycycline (Vibramycin), minocycline (Minocin), and tetracycline (Achromycin, Sumycin).


Magnesium can decrease bisphosphonate (e.g. Fosamax, Actonel, Didronel) absorption. If one separates doses of magnesium and these drugs by at least 2 hours, no adverse reaction can occur.


Magnesium inhibits calcium entry into smooth muscle cells and may therefore have additive effects with calcium channel blockers like amlodipine (Norvasc). Severe hypotension and neuromuscular blockades can occur when nifedipine (Adalat) another calcium channel blockers used with intravenous magnesium.  Does this necessitate removing magnesium from the market?  How about removing calcium channel blockers from the market?  Just be careful to avoid the two taken together.


Theoretically, increased magnesium levels could result from concomitant use of potassium-sparing diuretics and magnesium supplements. The potassium-sparing diuretics include amiloride (Midamor), triamterene (Dyrenium), and spironolactone (Aldactone).


Loop diuretics (furosemide (Lasix), bumetanide (Bumex), ethacrynic acid (Edecrin), and torsemide (Demadex)) and, to a lesser extent thiazide diuretics (hydrochlorothiazide (Esidrix, HydroDiuril), chlorothiazide (Diuril)), interfere with magnesium reabsorption in the kidneys, which increases urinary losses and reduces serum magnesium levels.


Estrogen therapy including the use of oral contraceptives lowers serum magnesium levels and can cause hypomagnesemia, especially in people with low dietary magnesium intake or other factors contributing to magnesium loss.




Magnesium is just one of numerous trace minerals that are highly important both for disease prevention and treating existing illness as far ranging as asthma, osteoporosis, migraine headaches, coronary artery disease and diabetes.  Before reaching for that anti-spasmodic, analgesic or anti-inflammatory drug, you might be better off considering healthy doses of magnesium.  The optimal doses depend on the health situation, the current magnesium level and other biochemical individuality factors.  If you are not sure what to do, consult a natural health care practitioner.


Dr. Zoltan P. Rona practises Complementary Medicine in Toronto and is the medical editor of “The Encyclopedia of Natural Healing.” He has also published several Canadian best-selling books, including “Vitamin D, The Sunshine Vitamin.” For more of his articles, see




Bolland MJ et al. Vascular events in older healthy women receiving calcium supplementation: randomized controlled trial. British Medical Journal



2008 doi:10.1136/bmj.39440.525752.BE

Jones G and Winzenberg T. Cardiovascular risks of calcium supplements in women (editorial).

 British Medical Journal


2008 doi:10.1136/bmj.39463.394468.80


Ishitani K, Itakura E, Goto S, Esashi T. Calcium absorption from the ingestion of coral-derived calcium by humans. J Nutr Sci Vitaminol (Tokyo) 1999;45:509-17.


Scelfo GM, Flegal AR. Lead in calcium supplements. Environ Health Perspect 2000;108:309-19.


Ross EA, Szabo NJ, Tebbett IR. Lead content of calcium supplements. JAMA 2000;284:1425-9.


Gulson BL, Mizon KJ, Palmer JM, Korsch MJ, Taylor AJ. Contribution of lead from calcium supplements to blood lead. Environ Health Perspect 2001;109:283-8.


Heaney RP, Dowell SD, Bierman J, Hale CA, Bendich A. Absorbability and cost effectiveness in calcium supplementation. J Am Coll Nutr 2001;20:239-46.


Sakhaee K, Bhuket T, Adams-Huet B, Rao DS. Meta-analysis of calcium bioavailability: a comparison of calcium citrate with calcium carbonate. Am J Ther 1999;6:313-21.


Heller HJ, Greer LG, Haynes SD, Poindexter JR, Pak CY. Pharmacokinetic and pharmacodynamic comparison of two calcium supplements in postmenopausal women. J Clin Pharmacol 2000;40:1237-44.


Weaver CM, Heaney RP. Calcium. In: Shils M, Olson JA, Shike M, Ross AC, eds. Modern Nutrition in Health and Disease. 9th ed. Baltimore: Williams & Wilkins; 1999:141-155.

Heaney RP. Calcium, dairy products and osteoporosis. J Am Coll Nutr. 2000;19(2 Suppl):83S-99S.  (PubMed)

Food and Nutrition Board, Institute of Medicine. Calcium. Dietary Reference Intakes: Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, D.C.: National Academy Press; 1997:71-145.  (National Academy Press)

Brody T. Nutritional Biochemistry. 2nd ed. San Diego: Academic Press; 1999.

Pearce SH, Thakker RV. The calcium-sensing receptor: insights into extracellular calcium homeostasis in health and disease. J Endocrinol. 1997;154(3):371-378.  (PubMed)

Calvo MS. Dietary considerations to prevent loss of bone and renal function. Nutrition. 2000;16(7-8):564-566.  (PubMed)

 Devine A, Criddle RA, Dick IM, Kerr DA, Prince RL. A longitudinal study of the effect of sodium and calcium intakes on regional bone density in postmenopausal women. Am J Clin Nutr. 1995;62(4):740-745.  (PubMed)

Carbone LD, Barrow KD, Bush AJ, et al. Effects of a low sodium diet on bone metabolism. J Bone Miner Metab. 2005;23(6):506-513.  (PubMed)

Wigertz K, Palacios C, Jackman LA, et al. Racial differences in calcium retention in response to dietary salt in adolescent girls. Am J Clin Nutr. 2005;81(4):845-850.  (PubMed)

Bonjour JP. Dietary protein: an essential nutrient for bone health. J Am Coll Nutr. 2005;24(6 Suppl):526S-536S.  (PubMed)

Barger-Lux MJ, Heaney RP, Stegman MR. Effects of moderate caffeine intake on the calcium economy of premenopausal women. Am J Clin Nutr. 1990;52(4):722-725.  (PubMed)

Harris SS, Dawson-Hughes B. Caffeine and bone loss in healthy postmenopausal women. Am J Clin Nutr. 1994;60(4):573-578.  (PubMed)

Lloyd T, Johnson-Rollings N, Eggli DF, Kieselhorst K, Mauger EA, Cusatis DC. Bone status among postmenopausal women with different habitual caffeine intakes: a longitudinal investigation. J Am Coll Nutr. 2000;19(2):256-261.  (PubMed)

Bostick R. Diet and nutrition in the prevention of colon cancer. In: Bendich A, Deckelbaum RJ, eds. Preventive Nutrition: The Comprehensive Guide for Health Professionals. 2nd ed. Totowa: Humana Press, Inc; 2001:57-95.

Bonithon-Kopp C, Kronborg O, Giacosa A, Rath U, Faivre J. Calcium and fibre supplementation in prevention of colorectal adenoma recurrence: a randomised intervention trial. European Cancer Prevention Organisation Study Group. Lancet. 2000;356(9238):1300-1306.  (PubMed)

Baron JA, Beach M, Mandel JS, et al. Calcium supplements and colorectal adenomas. Polyp Prevention Study Group. Ann N Y Acad Sci. 1999;889:138-145.  (PubMed)

Grau MV, Baron JA, Sandler RS, et al. Prolonged effect of calcium supplementation on risk of colorectal adenomas in a randomized trial. J Natl Cancer Inst. 2007;99(2):129-136.  (PubMed)

Cho E, Smith-Warner SA, Spiegelman D, et al. Dairy foods, calcium, and colorectal cancer: a pooled analysis of 10 cohort studies. J Natl Cancer Inst. 2004;96(13):1015-1022.  (PubMed)

Ma J, Giovannucci E, Pollak M, et al. Milk intake, circulating levels of insulin-like growth factor-I, and risk of colorectal cancer in men. J Natl Cancer Inst. 2001;93(17):1330-1336.  (PubMed)

National Institutes of Health. Osteoporosis Prevention, Diagnosis, and Therapy. NIH Consensus Statement. 2000;17(1):1-36.

Specker BL. Evidence for an interaction between calcium intake and physical activity on changes in bone mineral density. J Bone Miner Res. 1996;11(10):1539-1544.  (PubMed)

Heller HJ. The role of calcium in the prevention of kidney stones. J Am Coll Nutr. 1999;18(5 Suppl):373S-378S.  (PubMed)

Martini LA, Wood RJ. Should dietary calcium and protein be restricted in patients with nephrolithiasis? Nutr Rev. 2000;58(4):111-117.  (PubMed)

Curhan GC, Willett WC, Rimm EB, Stampfer MJ. A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones. N Engl J Med. 1993;328(12):833-838.  (PubMed)

Curhan GC, Willett WC, Speizer FE, Spiegelman D, Stampfer MJ. Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones in women. Ann Intern Med. 1997;126(7):497-504.  (PubMed)

Taylor EN, Stampfer MJ, Curhan GC. Dietary factors and the risk of incident kidney stones in men: new insights after 14 years of follow-up. J Am Soc Nephrol. 2004;15(12):3225-3232.  (PubMed)

Curhan GC, Willett WC, Knight EL, Stampfer MJ. Dietary factors and the risk of incident kidney stones in younger women: Nurses' Health Study II. Arch Intern Med. 2004;164(8):885-891.  (PubMed)

Liebman M, Chai W. Effect of dietary calcium on urinary oxalate excretion after oxalate loads. Am J Clin Nutr. 1997;65(5):1453-1459.  (PubMed)

Burtis WJ, Gay L, Insogna KL, Ellison A, Broadus AE. Dietary hypercalciuria in patients with calcium oxalate kidney stones. Am J Clin Nutr. 1994;60(3):424-429.  (PubMed)

Martini LA, Cuppari L, Colugnati FA, et al. High sodium chloride intake is associated with low bone density in calcium stone-forming patients. Clin Nephrol. 2000;54(2):85-93.  (PubMed)

Jackson RD, LaCroix AZ, Gass M, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006;354(7):669-683.  (PubMed)

Ritchie LD, King JC. Dietary calcium and pregnancy-induced hypertension: is there a relation? Am J Clin Nutr. 2000;71(5 Suppl):1371S-1374S.  (PubMed)

Kulier R, de Onis M, Gulmezoglu AM, Villar J. Nutritional interventions for the prevention of maternal morbidity. Int J Gynaecol Obstet. 1998;63(3):231-246.  (PubMed)

Levine RJ, Hauth JC, Curet LB, et al. Trial of calcium to prevent preeclampsia. N Engl J Med. 1997;337(2):69-76.  (PubMed)

Bruening K, Kemp FW, Simone N, Holding Y, Louria DB, Bogden JD. Dietary calcium intakes of urban children at risk of lead poisoning. Environ Health Perspect. 1999;107(6):431-435.  (PubMed)

Ross EA, Szabo NJ, Tebbett IR. Lead content of calcium supplements. JAMA. 2000;284(11):1425-1429.  (PubMed)


Alive Research Group; Gursche, Siegfried, Publisher; Rona, Zoltan P., Medical Editor.  

Encyclopedia of Natural Healing.  Vancouver:Alive Books, 1998.


Woods KL, et al, The Second Leicester Intravenous Magnesium Intervention Trial (LIMIT-2) Intravenous magnesium sulfate in suspected acute myocardial infarction: results of the second Leicester Intravenous Magnesium Intervention Trial (LIMIT-2). Lancet, vol 339, pp 1553-1558, 1992. 

Woods K.L., Fletcher S, "Long-term outcome after intravenous magnesium sulphate in suspected acute myocardial infarction : the second Leicester Intravenous Magnesium Intervention Trial (LIMIT-2), "Lancet, vol 343, pp 816-819, 1994

Ravn HB. Pharmacological effects of magnesium on arterial thrombosis--mechanisms of action? Magnes Research, vol 12, no 3, pp 191-9, 1999 

Young IS, et al, "Magnesium status and digoxin toxicity." Br J Clin Pharmacol, vol 32, no 6, pp 717-21, 1991 

Lewis R, et al, "Magnesium deficiency may be an important determinant of ventricular ectopy in digitalised patients with chronic atrial fibrillation." : Br J Clin Pharmacol, vol 31, no 2, pp 200-3, 1991

Seelig MS, "Cardiovascular Reactions to Stress Intensified by Magnesium Deficit in Consequences of Magnesium Deficiency on the Enhancement of Stress Reactions; Preventive and Therapeutic Implications: A Review." Journal of the American College of Nutrition, vol 13, no 5, pp 429-446, 1994.

Altura BM, Altura BT. "Role of magnesium in patho-physiological processes and the clinical utility of magnesium ion selective electrodes." Scand J Clin Lab Invest Suppl, vol 224, pp 211-34, 1996 

Altura BT, Altura BM, "A method for distinguishing ionized, complexed and protein-bound Mg in normal and diseased subjects." Scand J Clin Lab Invest Suppl, vol 217, pp 83-7, 1994 

Tunstall-Pedoe H, Kuulasmaa K, Mahonen M, Tolonen H, Ruokokoski E, Amouyel P. Contribution of trends in survival and coronary-event rates to changes in coronary heart disease mortality: 10-year results from 37 WHO MONICA project populations. Monitoring trends and determinants in cardiovascular disease. Lancet. 1999 May 8;353(9164):1547-57McKevoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.


Whitney E, Cataldo CB, Rolfes SR, eds. Understanding Normal and Clinical Nutrition. Belmont, CA: Wadsworth, 1998.


Meacham SL, Taper LJ, Volpe SL. Effect of boron supplementation on blood and urinary calcium, magnesium, and phosphorus, and urinary boron in athletic and sedentary women. Am J Clin Nutr 1995;61:341-5


de Valk HW, Verkaaik R, van Rijn HJ, et al. Oral magnesium supplementation in insulin-requiring Type 2 diabetic patients. Diabet Med 1998;15:503-7


Nielsen FH, Hunt CD, Mullen LM, Hunt JR. Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women. FASEB J 1987;1:394-7

Zoltan Rona
Zoltan Rona