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Calcium's heart protective benefits are well documented and high total calcium intake from food is linked with a lower risk of clogged arteries. However, calcium intake from supplements, specifically inferior forms of the mineral, are not absorbed and actually decrease the digestibility of other nutrients, while increasing the risk of coronary artery calcification (CAC), a ten-year follow-up of over 5000 adults has found.

Those with the highest total calcium intakes from foods compared to the lowest intakes generally have a minimum of a 20% lower risk of CAC. If we take too much Calcium (and to a slightly lesser degree, Magnesium) at once, it will cause the body pH to rise, and the body is quick to dump calcium and other minerals to check the rise in alkalinity, but where does the calcium go?

A 2004 study showed that people with excess calcium in their coronary artery and who take statins have a 17-fold higher risk of heart attacks than do those with lower arterial calcium levels; researchers concluded that the two most definitive indicators of heart attack were LDL levels and calcium build-up.

A 2007 study showed that calcium from dietary sources has more favorable effects on bone health than calcium from supplements in postmenopausal women (Am J Clin Nutr 2007).

A 2008 study found calcium supplements are associated with a greater number of heart attacks in postmenopausal women (BMJ 2008).

Stroke victims have higher levels of calcium in their coronary arteries, raising the possibility that calcium levels could identify people at risk for strokes

A 2010 meta-analysis showed calcium supplements (without co-administered vitamin D) are associated with increased risk for heart attack (BMJ 2010).

A 2014 study in the US found that 9% of women taking calcium supplements showed evidence of hypercalcemia and 31% had hypercalcuria.

Now new research published in the Journal of the American Heart Association (JAHA) has again found that that the use of calcium supplements may actually increase the risk for incident CAC and therefore jeopardise heart health.

In fact when considering supplement use, the risk of developing CAC was 22% higher in those who used calcium supplements compared to those who didn't.

These conclusions were based on the study of 5,448 adults free of clinically diagnosed cardiovascular disease aged between 45 and 84.

The research came in response to recent data suggesting calcium supplements may increase the risk of cardiovascular disease events.

The dairy industy has been hard at work the last 50 years convincing people that pasteurized dairy products such as milk or cheese increases bioavailable calcium levels. This is totally false. The pasteurization process only creates calcium carbonate, which has absolutely no way of entering the cells without a chelating agent. So what the body does is pull the calcium from the bones and other tissues in order to buffer the calcium carbonate in the blood. This process actually causes osteoporosis. Moreover, it has been found that magnesium, not calcium is the key the healthy bones and many other processes in the body.

Type of Calcium Ingested Is Key

Most supplements on the supplement market today contain calcium carbonate which is an inferior form of calcium and manufacturers attach a simple chelating agent like citric acid to make it more absorbable, however the end product is inferior to other calcium supplements such as calcium orotate, which is the only known form of calcium which can effectively penetrate the membranes of cells.

Calcium and all minerals actually, are inorganic. Consequently, they are not easily absorbed. It's required they be bound to some other substance (preferably organic) in order to be utilized at all. The inorganic salt, carbonate, neutralizes a required stomach acid. Among many key physiological requirements and ratios, stomach acid is desperately needed for absorption of ALL minerals.

With the support of medical research, the market has been flooded with calcium supplements, many which fail to take into consideration calcium metabolism. You have all heard the old saying, "You are what you eat." In light of today's food supplies, it may be more apropos to say "You are what you absorb." A mineral that is not absorbed cannot get into the bones and critical body systems; it just floats in the blood stream and then forms deposits in the joints. The amount absorbed is more important than the quantity consumed.

If patients demand a supplement for calcium intake they must seek a reputable and balanced calcium/magnesium formula. Researchers examined 21 formulations of calcium carbonate (both natural [i.e., oyster shell] and refined). Four out of seven natural products and four out of 14 refined products, including brand products, had measurable lead content. A research team in California found essentially the same contamination in calcium supplements.

Acid rebound. Calcium carbonate may cause acid rebound: the stomach overcompensates for the high dose of calcium carbonate, which is alkaline, by churning out more acid. For that reason, people with a history of stomach ulcers are advised that they may not tolerate it and may have to switch to calcium citrate.

Constipation. Calcium supplements can have a mild binding effect but by themselves don't usually cause serious constipation. But if you're taking another supplement or medication that binds the stool, the addition of calcium supplements could cause a problem.

Too much calcium. Although it doesn't happen often, some people have taken so much calcium that it causes hypercalcemia, an above-normal level of calcium in the blood since most of the calcium carbonate is not absorbed. Hypercalcemia may cause nausea, vomiting, confusion, and other neurological symptoms.

The type of minerals in the formula determines the absorption levels: Opti-Cal/Mag with Vitamin K2 is an example of a co-enzyme complex, heat-stabled molecules that must be associated with another enzyme for them to perform their function in the body. It is necessary in the utilization of vitamins and minerals for proper delivery to the cell nucleus. One study found that Opti-Cal/Mag complex is 8.79 times more absorbed into the blood than calcium carbonate and 2.97 times more than calcium gluconate.

Another interesting study found that calcium from bone meal/powder is absorbed 1.13 times more than calcium carbonate, the variety found in most supplements. Clinical reports consistently confirm that dietary/food calcium in its more absorbable form benefits in the management of lowering blood levels of cholesterol, triglycerides and blood pressure. Other health concerns from calcium deficiencies can contribute to muscle cramps, insomnia, mood/behavioral/nerve problems, hypertension, growth problems, kidney stones, and colon cancer. More recent research indicates that calcium also plays a role in preventing cancer by detoxifying potentially cancer-causing compounds in the bowel.

Over Compensating

"Excessive dietary calcium intake, particularly from overconsumption of calcium supplements taken to prevent or treat osteoporosis, may have unintended health consequences. The well-known 'milk'-alkali syndrome has been increasing in incidence attributed to the widespread use of over-the-counter calcium supplements," the researchers wrote.

"Supplements contribute to calcium loading (ie, excessive calcium amounts in a single dose or bolus), which leads to an increase in urinary calcium excretion in adults with normal renal function, with or without hypercalcemia, and possibly to soft tissue or ectopic calcification."

The US researchers behind this latest cohort paper sought to address this "controversial" question using CAC " highly common in patients with coronary heart disease" as a marker of heart health.

"[W]e found evidence that calcium supplement use was independently associated with incident CAC, whether or not we adjusted for total calcium intake," concluded the researchers from the University of North Carolina, University of Washington, Indiana University, Wake Forest School of Medicine, Emory University, the Washington Patient-Centered Outcomes Research Institute, the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Centre and Johns Hopkins University in the US.

"This finding suggests that calcium loading with supplements may not be entirely free of undesirable side effects, especially considering evidence for events in randomised trials of calcium supplementation like the Women's Health Initiative."

How Much Is Too Much?

Yet looking closely at the levels consumed via the supplements, the British Nutrition Foundation (BNF) urged caution.

"The recommended intake for calcium is higher in the US than the UK," science director for the charity, Sara Stanner stated.

Holland & Barrett's own brand calcium supplement contains a daily dose of 1,000 mg, which it marks as 125% of the UK's daily recommendation. Other third party calcium supplements on the popular UK retailer's website contain at least 800 mg per adult daily dose.

"Here [in the UK] the RNI [Reference Nutrient Intake] is 700 mg/day for 19-50 year olds. So the groups with the highest intakes were consuming supplements with doses much higher than the recommended amount."

In the US its Institute of Medicine recommends calcium intakes of 1,200 mg/day for women and 1,000 mg/day for men aged 51 years and older.

Yet the highest quintile of calcium intake in the study was nearly double this at 2,157 mg per day.

Last year the European Food Safety Authority (EFSA) set various Population Reference Intakes (PRIs) for different age groups including 950 mg per day for adults over the age of 25.

Meanwhile the British Heart Foundation (BHF) urged those prescribed calcium for bone conditions such as osteoporosis not to stop taking the medication and to contact their doctor if they have any concerns.

Senior dietitian for the heart charity, Tracy Parker, told us: "This study shows a protective relationship between our total calcium intake and coronary heart disease, caused by a build-up of fatty material inside your arteries which could lead to a heart attack.

"However, this research only found an association between people who used calcium supplements and risk of coronary heart disease; this does not mean that calcium supplements could directly increase your risk of heart disease."

She added: "Following a balanced diet should provide all the calcium the body needs to keep healthy."