Heart Health

Updated 27 September 2016

Calcium tabs up heart-attack risk

Alarm bells are ringing: new research shows that calcium supplements may increase women's risk of heart attack, stroke and sudden death. Read DietDoc's comments.

When two articles arrived on my desk in a short space of time warning that calcium supplementation may increase the risk of heart attacks, stroke and sudden death in postmenopausal women, alarm bells started ringing.

Dietary advice must always be based on the most recent scientific research that is available to practitioners. For more than a decade, dieticians and members of the medical profession have recommended the use of calcium supplements for postmenopausal women to prevent osteoporosis, a debilitating and sometimes fatal condition. However, these latest reports indicate that that advice may need to be revisited.

New Zealand study
A study conducted in New Zealand among 1 471 postmenopausal women, who either received calcium supplements (1g of elemental calcium a day) or placebo (dummy medication) for a period of five years, produced alarming results:

  • Myocardial infarction (heart attack) was more common in the group of women who took the calcium supplements.
  • Strokes or sudden death were also much more frequent in the calcium group.

According to the study author, Bolland, and the co-authors, “Calcium supplementation in healthy post-menopausal women is associated with upward trends in cardiovascular event rates.”

Bolland and his team suggest that the increased risk of so-called cardiovascular events could be caused by increased deposits of calcium in the arteries, which in turn causes blockages.

Are there any solutions?
On one hand, low calcium intakes are associated with osteoporosis, which can severely reduce quality of life and even result in death in postmenopausal women and older men. On the other hand, we now have these research results that suggest that taking calcium supplements could make one susceptible to disease more dangerous than osteoporosis.

As a dietician, my advice to all postmenopausal women and older men would be to focus on a well-balanced diet that contains sufficient calcium derived from natural sources (e.g. milk, yoghurt, cheese) and to spend at least 30 minutes a day in the sun so that their bodies can produce vitamin D. Don't take calcium supplements unless your doctor has diagnosed signs of osteoporosis and you're for some reason unable to obtain your calcium and vitamin D from natural foods and sunshine exposure.

Vitamin K2
If you have been told to take a calcium and/or vitamin D supplement, it may be a good idea to use a supplement that also contains vitamin K2 (for example, the recently launched MenaCal.7).

Vitamin K2 is one of a group of fat-soluble vitamins called quinones that ensure that the body makes proper use of calcium for healthy bones, arteries and tissues (Med Chron, 2008). It has long been known to help blood coagulation, but recently a very large study conducted in Europe (the Rotterdam Study), it found that it also prevents osteoporosis, and cardiovascular disease.

The mechanics of vitamin K2 are that it activates a bone protein called osteocalcin, which binds calcium in the bones, thus preventing calcium from moving into the bloodstream and being deposited in the arteries, with often fatal consequences.

The Rotterdam Study tracked the health of 4 800 initially healthy individuals from the age of 55 years for a 10-year period. Subjects who ingested at least 45 micrograms of vitamin K2 per day had a significantly reduced risk of cardiovascular disease (57% less risk of heart attacks and stroke) and a 26% decreased risk of death from all causes. The risk of arterial calcification was reduced by 52% in the group of subjects who had the highest vitamin K2 intake from dietary sources.

Researchers are now saying that to prevent osteoporosis and heart disease/stroke, we need to combine calcium, vitamin D (this helps us absorb the calcium) and vitamin K2 (this binds the calcium in bones and prevents it reaching our arteries).

Sources of vitamin K
As always, it's better to obtain your vitamin K2 from foods. The following foods are sources of vitamin K:

  • Green leafy vegetables such as broccoli, cabbage, turnip greens, and the dark green leaves of lettuce (about 100 microgram/100g)
  • Dairy products, meat, eggs (about 50 microgram/100g)
  • Fruit and cereals (about 15 microgram/100g).
    (Mahan & Escott-Stump, 2000)

The recommendation that we should be eating plenty of fresh vegetables on a daily basis also holds true for vitamin K2 intake.

New calcium supplement
MenaCal.7, the new calcium, vitamin D and vitamin K2 supplement that has just been launched in South Africa is designed to “keep calcium in its place – in your bones where it belongs, and out of your arteries where it can increase your risk of a heart attack.” (Bryer, 2008)

According to its distributors, MenaCal.7 received the 2008 Frost & Sullivan Product Innovation of the Year Award and is now regarded as the solution to the calcium-osteoporosis-arterial calcification problem. The product is available in most pharmacies.

Our first line of defence is, therefore, to make quite sure that we're eating a balanced diet that provides sufficient calcium and vitamins D and K2. Daily exposure of the skin to the sun will also benefit vitamin D production. However, if you can't obtain these nutrients from your diet, then the new MenCal.7 may be the solution to osteoporosis and heart disease.

(Dr I.V. van Heerden, DietDoc, December 2008)

(Bolland MJ et al (2008). Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial. British Medical Journal, 336:262-266; Bryer L (2008) Is calcium supplementation a cause for concern? Press Release 03/12/08; Mahan LK, Escott-Stump S (2000). Krause’s Food, Nutrition & Diet Therapy. 10th Ed. WB Saunders Co, Philadelphia; Medical Chronicle (2008).Is calcium supplementation a cause for concern? Med Chron, Nov 2008, p. 82)

Any questions? Ask DietDoc


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