The most wonderful thing about science is that it’s perfectly OK – actually it’s encouraged – to change your mind when new information comes about.
This is what makes me angry about religion and politics. One refuses to change or changes very slowly, and in the other you are considered a flip-flopper. I’m about to change my mind on the whole calcium/magnesium supplementation based on this one study, published on May 23, 2012 in the British Medical Journal.
This prospective cohort study was called:
Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition study
It was performed in Europe with almost 24,000 participants, and average follow up was 11 years. The study showed a statistical significance of MI (myocardial infarction or heart attack) for calcium supplement users. There was no increase in stroke or CVD (death by heart attack). Previously thought to help the heart, calcium supplements have now shown to harm it.
This study seems pretty comprehensive – a large population and a long follow up. The only problem I see is that it’s a cohort study, not a randomized controlled trial – the RCT is preferable when it can be done (I can see that an 11 year average for this one would make it very hard to do).
So I retract my previous calcium/magnesium comments, and firmly hold on to the privilege of changing my mind.
I’ve stopped taking the supplements today, but the calcium already in my diet should be plenty (spinach, cheese, nuts)…
I went back briefly to calcium/magnesium supplements every second day for a month or so, mostly because my sleep was suffering (real or imagined). I then re-thought the whole process, and said “I can work through this” to myself. And I did. I’ve been off calcium/magnesium supplements for a few weeks now, and there was an initial rebound insomnia to deal with. But I’ve been careful to make sure I have enough dietary sources of calcium (cheese, spinach – often in the same salad) to make sure my levels are close to optimum. And now my sleep has returned to the “new normal” for me (not like it was five years ago, but good enough for an insomniac!).