Are Calcium Supplements Bad For Your Heart?

It is well known that adequate calcium intake is important for bone health at all ages.  Calcium supplementation is common, with 43% of American adults (and 70% of postmenopausal women) regularly taking calcium supplements.  However, there is a lot of confusing information out there, with some studies suggesting that calcium supplements may increase the risk of heart disease.

A recent article in the New England Journal of Medicine provides an excellent discussion around the controversies of calcium supplementation and heart health.   Here are some key points:

1.  The recommended daily calcium intake for Canadian adults:

• age 19-50: 1,000 mg of elemental calcium per day (see #4 below re the meaning of 'elemental' calcium)
• men age 51-70: 1,000 mg
• women age 51-70: 1,200 mg
• adults over 70 years: 1,200 mg

2.  The evidence suggesting that calcium supplements may increase the risk of cardiovascular disease is inconsistent - in other words, we still don't have a definitive answer to this question.  Compiled data from several studies pooled together (called 'meta-analyses') have suggested increased risk, while a large randomized controlled trial called the Women's Health Initiative (WHI) did not show an increased risk.  (Randomized controlled clinical trials provide more trustworthy evidence than meta-analyses do, so the fact that the WHI didn't show an increased risk carries weight.).  

It has been speculated that a sharper increase in blood calcium levels after eating a calcium supplement may result in increased cardiovascular risk, but this has not been proven. 

3.  Given that it is still not clear whether calcium supplements increase cardiovascular risk or not, getting the recommended calcium intake from food and beverages is the preferred approach.  

We consume about 300mg of elemental calcium per day from non dairy sources.  Here are some examples of dairy and non-dairy calcium sources: 

• 1 cup of milk: 300 mg
• 1 serving of yogurt (100g): 100 mg
• 1 oz cheddar cheese: 200 mg
• 1 cup low fat cottage cheese: 200 mg
• 1 cup raw broccoli: 43 mg
• 1 cup raw kale: 100 mg
• 1 slice bread (commercially prepared): 30-70 mg
• fortified breakfast cereal - varies widely - check the label!

4.  If you need to use calcium supplements over and above dietary intake to reach your recommended calcium intake, check the label for the mg of elemental calcium, as this is the value that is important.  Calcium supplements come in many different forms (calcium carbonate, calcium gluconate, calcium citrate etc), and each type of calcium supplement contains a different percentage of elemental calcium.  If your supplement doesn't say how many mg of elemental calcium it contains, here is a guide: 

• calcium carbonate: contains 40% elemental calcium (so, if your supplement is 750mg of calcium carbonate, it contains 300 mg of elemental calcium)
• calcium citrate: contains 21% elemental calcium
• calcium gluconate: contains 9% elemental calcium

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Risk of Cancer After Nuclear Accidents

With the recent Fukushima disaster (pictured above), the topic of nuclear disasters is at the forefront of all of our minds.  Nuclear accidents are a terrible tragedy on so many levels, from the damage done to the environment, to the effects on wildlife, the people, the society, and the economy of the country affected.    Once the initial period of damage control and clean up is tended to, the work and surveillance of the population from a health standpoint has only just begun.  A recent article in the Canadian Medical Association Journal provides a poignant reminder of this fact.

The article by Dmytriw and Pickett describes the case of a man who developed a glioblastoma brain tumor which occurred 24 years after his exposure to the Chernobyl nuclear disaster in 1986.  The Chernobyl power plant disaster remains the worst accident at a nuclear power plant in history, resulting in radioactive fallout covering large parts of the western former Soviet Union.  While the studies in the 4 years after Chernobyl found an increased incidence of leukemia, thyroid cancer did not show to be significantly increased until 16 years after the Chernobyl accident, at which time the risk was found to be 4.3 times that of the general population.  These papillary thyroid cancers were also found to be more aggressive in their behavior than typical papillary thyroid cancers.

Going beyond this time frame into today, now 27 years after Chernobyl, it is hard to quantify the risk of tumors caused by Chernobyl, as follow up of people who lived in the affected area becomes very difficult.  An increased risk of breast cancer and brain tumors has been suggested, but difficult to prove definitively.  In terms of distance from Chernobyl that can put a person at risk, the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR) has indicated that individuals who lived as far as 2,000 km away from Chernobyl may develop cancer beyond the minimum latency times normally associated with exposure to radiation.

The bottom line?  As health care providers, we must remember to ask about exposure to nuclear accidents, remembering that tumors can develop more than 20 years after exposure.  If you are a person that has been exposed to a nuclear disaster such as Chernobyl or Fukushima, make sure your health care providers over the long term are aware.

Finally, cases of cancer that arise among people who were exposed to nuclear accidents should be reported to the appropriate authority, with the patient's consent.

The Fukushima Registry for cases of cancer amongst people who were living in Japan at the time of the Fukushima disaster is accessed by emailing ftiiki@fmu.ac.jp.

The Chernobyl Registry for cases of cancer amongst people who were living in Ukraine, Belarus or Russia around the time of the Chernobyl disaster is accessed by emailing info@nrer.ru (for Russia or Belarus) and moz@mov.gov.ua (for the Ukraine).

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Aircraft Noise Exposure May Increase Heart Disease and Stroke Risk

Regular readers will know that I often talk about pollutants and chemicals in our environment that may adversely affect our health (from water bottles to soup cans to the soap we use, and many more).  I came across some interesting articles in my reading this week that add to the literature suggesting that even noise pollution may be dangerous to our health.

In the recent edition of the British Medical Journal, there are two studies and an editorial review discussing the risk of stroke and heart disease for people who live in proximity to airports.

As Dr Fiona Godlee, editor in chief of the journal writes:


The first study compared hospital admissions and mortality rates for stroke, coronary heart disease, and cardiovascular disease from 2001-05 in 12 London boroughs and nine districts west of London. The researchers found increased risks of stroke, coronary heart disease, and cardiovascular disease for both hospital admissions and mortality, especially among the 2% of the study population exposed to the highest levels of daytime and night time aircraft noise.

In the second study, researchers at the Harvard School of Public Health and Boston University School of Public Health analysed data for over six million older American Medicare recipients (aged 65 years or more) living near 89 US airports in 2009.
The researchers found that, on average, zip codes with 10 decibel (dB) higher aircraft noise had a 3.5% higher cardiovascular hospital admission rate. The association remained after adjustment for socioeconomic status, demographic factors, air pollution, and roadway proximity.

An accompanying editorial says the results have implications for planners when extending airports in heavily populated areas or planning new airports.


As noted in the editorial by Professor Stansfeld, 

These studies provide preliminary evidence that aircraft noise exposure is not just a cause of annoyance, sleep disturbance, and reduced quality of life but may also increase morbidity and mortality from cardiovascular disease. The results imply that the siting of airports and consequent exposure to aircraft noise may have direct effects on the health of the surrounding population. Planners need to take this into account when expanding airports in heavily populated areas or planning new airports.


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