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What Will Happen if I Consume Too Much Calcium?

The same thing as if you don't get enough. You'll be more likely to die sooner.

Theodore Dalrymple


February 23, 2013 - 7:00 am

It is tempting for people to suppose that if a little of something is good for them, then a lot of it must be better. Unfortunately this is not always or even usually the case; and I first realized that people are inclined to make this mistake when, as a student many years ago, I was shown a baby who was bright orange; it was suffering from a condition known as carotenemia. The parents, having heard that carrots were healthy, concluded that only carrots were healthy, and fed their baby accordingly.

A study from Sweden, recently published in the British Medical Journal, examines the important question of whether calcium supplements are good for middle-aged and old women. The question is important because millions of women around the world take such supplements – 60 percent of American middle-aged and old women, for example. There is no one quite like the Swedes for carrying out such epidemiological studies because the medical records of their population are by far the most comprehensive in the world: creepily so, one is sometimes inclined to think.

What the Swedish researchers found was that the graph of the relationship between calcium intake and death rates was a U-shaped curve. People with a low consumption of calcium had a higher mortality than those with a moderate consumption, but so did people with a high consumption.

The sample of women was not small, and in the period of study 11,944 of the 70,259 women studied had died. Those with a high dietary consumption of calcium alone had an increased death rate of 1.4 times for all causes of mortality, 1.49 times for cardiovascular mortality, and 2.14 times for ischaemic heart disease (heart attacks) compared with those whose who consumption of calcium was associated with the lowest mortality, that is to say a moderate consumption.

It was worse for those with a high dietary consumption of calcium who in addition took calcium supplements, either in the form of multivitamins or calcium tablets. Their all-cause mortality was 2.57 times that of those with a moderate consumption of calcium. According to the authors, “among women with a high dietary intake of calcium, the addition of calcium increased the risk of death in a dose dependent fashion.” This is evidence that the relationship was not just that of statistical association, but of causation.

Interestingly, the women who took calcium supplements, whether as multivitamins or as calcium tablets, were likely to live healthier lifestyles than those who did not: to exercise more, eat more healthily, etc. In other words, they were probably more inclined to do things for the sake of their health, even those things that in the event turn out not to be so good for the health. As Hegel said in another connection, the Owl of Minerva takes wing by night.

There was something I did not quite understand, or at least that surprised me, in the figures given by the authors of this paper. I quote:

11,944 women died; of these women, the underlying cause of death was cardiovascular disease in 3862 ischaemic heart disease in 1932, and stroke in 1100.

Now cardiovascular disease encompasses, among other things, ischaemic heart disease and stroke, that is to say 3032 of the 3862 cardiovascular deaths, leaving 830 others. I think this large latter number will come as a surprise to any doctor.

Nevertheless, the paper is potentially important, especially if it is replicated elsewhere (for you should never put your faith in one study alone, especially when it depends upon the manipulation of complex statistics), for it suggests that the benefit of calcium supplementation is not only the medical equivalent of an urban myth, but a dangerous one at that.


images courtesy Shutterstock /  Christian Jung / Stokkete

Previously from Dr. Dalrymple:

Human Feces as Medicine?

How a Mammogram Can Kill You

What Can Be Done to Reduce Post-Hospital Syndrome?

What Is the Best Way to Treat Diabetes?

The Worldwide Evolution of Life Expectancy

The Sleep-Deprived Doctor Saving Your Life

As Life Expectancy Increases Will the Elderly Become a Greater ‘Burden on Society’?

Should Doctors Lie to Their Patients About Their Survival Chances?

How Doctors Turn Their Patients into Drug Addicts

Theodore Dalrymple, a physician, is a contributing editor of City Journal and the Dietrich Weismann Fellow at the Manhattan Institute. His new book is Second Opinion: A Doctor's Notes from the Inner City.

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All Comments   (9)
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Too much of anything is bad for you, including water (water intoxication, hyponatremia) and oxygen (oxygen toxicity).
2 years ago
2 years ago Link To Comment
I can't deal with this.
2 years ago
2 years ago Link To Comment
A doctor I know says that without enough of the right kind of magnesium then calcium is not absorbed properly by the body and contributes to clogging of the arteries. And you need more MG than calcium, by a ratio of 2 or 3 to one.

And just common MG Oxide is not the right kind. Mg Oxide is not absorbed but by a small portion of the colon. You need Mg Asperate and Mg Citrate, and which one depends on whether the objective is to strengthen the bones or help control blood pressure.

So it is quite believeable that too much calcium is bad for you, especially if there is inadequate Mg.
2 years ago
2 years ago Link To Comment
Word. I used to take a ton of vitamin E since it helped with my acne. Now I have a pacemaker. Oh yeah; don't use anti dandruff salicylic acid too long either (not heart related; causes other problems)...
2 years ago
2 years ago Link To Comment
Just a note referring to your question on those 830.

Actually, if you take a look at the third and last sentence under the “Outcomes” paragraph, the authors have differentiated among cardiovascular disease, ischemic heart disease, and stroke because evidently that’s what the ICD-9 and 10 do: they give codes for all three; so those 830 would actually be part of the 11,944 “all causes” cohort:

“We used the underlying cause of death in the registry to define the outcomes of death from all causes, cardiovascular disease (international classification of diseases, ninth and 10th revisions; ICD-9 codes 390-459 or ICD-10 codes I00-I99), ischaemic heart disease (ICD-9 codes 410-414 or ICD-10 codes I20-I25), and stroke (ICD-9 codes 430-436 or ICD-10 codes I60-I64).”

(They used the phrase “cause specific cardiovascular disease” in the “Abstract” section, which could have used a hyphen, and a semi-colon after “causes” in the paragraph above, both of which would have improved clarity—probably both casualties of the less than punctilious editing that can occur in these pre-pub pieces, but for which the general public as well as the scientific community are nontheless most grateful.)

2 years ago
2 years ago Link To Comment
Let me hasten to add that the whole article is so rife with punctuation errors (including many more in the quoted paragraph) that it’s a wonder you could slog through it on our behalf, which I for one certainly appreciate. And perhaps the original language was Swedish. :-)
2 years ago
2 years ago Link To Comment
The missing concept here is that calcium must be balanced with magnesium. When you introduce exogenous calcium, there is not enough magnesium stored in the body to deal with it, and your calcium supplements have only created a magnesium deficiency. Magnesium deficiency is characteristic of patients with cardiovascular disease. Excess magnesium is easily excreted, it is a harmless macro mineral as compared with calcium. Excess calcium is bad news for neurons, also, magnesium is protective: see the writings of neurosurgeon Russell Blaylock.

The relationship between calcium and magnesium is analogous to the relationship between sodium and potassium. Potassium is excreted very easily, no matter how abundant it might be in a natural diet. Excess sodium is another matter, intake of sodium is best limited because too much of it causes problems.

So what to do about calcium? Just make sure you eat foods like cheese, you will get enough in a good diet. Consider supplementing with magnesium.
2 years ago
2 years ago Link To Comment
What is a moderate amount of calcium?
2 years ago
2 years ago Link To Comment
That's my question as well.
2 years ago
2 years ago Link To Comment
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