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 QUICK FACTS
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.
IS YOUR CALCIUM IN THE RIGHT PLACE?
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.
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
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)
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
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
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
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
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.
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
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 www.mydoctor.ca/drzoltanrona
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