Calcium supplements - health warning

I've c&p the article below for those who don't want to subscribe (free) to New Scientist to read it:

Calcium dementia link is reminder of the dangers of supplements

An increased risk of dementia in some women taking calcium warns us that supplements marketed as a quick fix for health may not be benign, says Clare Wilson

Taking supplements to be ‘on the safe side’ doesn’t necessary produce the desired benefits

By Clare Wilson

Taking a daily vitamin or mineral supplement is widely seen as a common-sense way of looking after yourself – a kind of insurance, like wearing a seat belt.

But evidence is growing that it might not be such a healthy habit after all. The latest finding is that calcium supplements, taken by many women after the menopause to strengthen their bones, are linked to dementia. Among women who have had a stroke, taking calcium was associated with a seven-fold rise in the number who went on to have dementia. Calcium was also linked with a smaller, non-statistically significant, rise in dementia in women who had not had a stroke.

The finding emerged from a study that was not a randomised trial, so it is not the most robust type of medical evidence. The researchers merely counted dementia cases in people who had chosen whether to take calcium, and so the data could be biased. But the results are striking and come on the heels of a previous study that was a randomised trial, which found a link between calcium supplements and a modestly higher risk of heart attacks – suggesting that caution over calcium is indeed warranted.

If future research confirms the association with dementia, women would face a horrible dilemma: should they continue to take calcium, staving off bone weakness that can lead to fatal hip fractures, while running an increased risk of one of the most dreaded illness of ageing?

No magic wand

So what’s going on? Team member Silke Kern at the Sahlgrenska Academy Institute of Neuroscience and Physiology in Gothenburg, Sweden, says that taking a calcium pill triggers a rapid surge in the mineral’s levels in the blood, one that you wouldn’t get from calcium in food. Such a spike could make blood more likely to form harmful clots – which could trigger heart attacks – or could harm brain cells, resulting in a higher incidence of dementia, she says.

But there are wider lessons here. The importance of vitamins and minerals in our diet emerged mainly in the early 20th century thanks to striking deficiency diseases seen in the poor. For example, children grew up with the bowed legs of rickets, caused by a lack of vitamin D.

The discovery that we could make such nutrients artificially and add them to food or turn them into pills must have seemed like a magic wand for health. It was understandably tempting to conclude that even well-fed individuals might benefit from taking supplements, “to be on the safe side”.

Today about a two-thirds of people in the US take a daily supplement. This includes those who take multivitamin and mineral pills, as well as people who take individual ones, like calcium, or combinations targeted at certain health needs, like protecting ageing joints, preventing colds or promoting hair and nail health.

But while adverts for such pills can be slick, often featuring athletes and celebrities testifying to their benefits, the evidence is remarkably lacking. In the US and UK, there is, shamefully, no need for supplement-makers to carry out trials showing their products have the claimed effects.

A to zinc: Which supplements are worth taking, and which definitely not?

Rather than just failing to do good, some supplements may even be harmful – as with calcium.

People also like to take antioxidants – including the vitamins A, C and E, and the mineral selenium – because of the belief they ward off cancer by blocking damaging oxidising compounds produced during metabolism.

But when put to the test, this idea falls down spectacularly. Trials show that those taking antioxidants have a slightly higher death rate than those who don’t.

The explanation for this finding is still unclear. It could be because we have misunderstood how antioxidants work, or because plants contain thousands of protective phytochemicals and taking a few in isolation just doesn’t have the same benefits.

In the case of calcium, it isn’t too hard to get all we need from natural sources. The UK recommended intake of 700 milligrams a day could be met by consuming, for instance, 300 millilitres of milk, a 100-gram pot of yogurt and a small 30-gram wedge of cheese. (The US recommended daily amount is a bit higher, at 1000 milligrams for most adults and 1200 milligrams for over-70s, but not unfeasibly so.)

With the exception of folic acid, which trials have shown prevents birth defects if taken before and during pregnancy, many dieticians now say that supplements are no substitute for a healthy and varied diet, with plenty of fruit, vegetables and dairy produce or its equivalents. There’s no better health insurance than that.

Journal reference: Neurology, DOI: 10.1212/WNL.0000000000003111

34 Replies

Good article Clutter, thanks for posting.


It was mentioned on R4 during the week but I snagged the link from PAS.

I don't think people realise how dodgy supplementing with calcium can be, the range is fairly tight and going over into hypercalcemia can be dangerous, even more so when there are parathyroid problems, diagnosed or not.


I've always said one shouldn't supplement unless calcium deficient. May say it in CAPS in future :)

This subject pops up quite frequently on Malcolm Kendrick's blog too.

My multi vit/mineral doesn't include calcium, iron or copper. I choose to add in 1 mg copper, plus magnesium and potassium in varying quantities - the latter two are needed because I self-inject cobalamin for my PA. I get plenty of calcium and iron from my diet.


I can't see the point in multi-vits particularly when some have calcium and iron in the same tablet.

It worries me a bit that some doctors automatically prescribe calcium with D3 when the patient is vitD deficient but not calcium deficient too.

I quite agree. My multi contains bio-available forms of some nutrients I lack, or have difficulty absorbing, but I chose it carefully after quite a lot of thought. I don't think it's a good idea to supplement without a clear idea of why one is doing so.

@Clutter The guidelines in ALL the NHS areas I've managed to look at state not to prescribe calcium for those who are vitamin D deficient, so it is very worrying that doctors are still doing that.

@bluebug One GP automatically prescribed Calcium with Vit D when I was found to be low in Vit D, but I stopped taking it when I realised that Ca could be dangerous. I know other people who have also been prescribed the same thing after breaking a bone, even without a Vit D test. As you say, it's very worrying.

Me to 😀

There was a section on Monday's Woman's Hour on BBC Radio 4:

Also worth noting that hypocalcaemia (low serum calcium) is a dementia risk!

Thanks for this Clutter. My 6 year old son is dairy intolerant and I have been advised to give him a calcium supplement. Do you think this is a good idea or could it lead to future health problems? (btw he has some coconut milk with added calcium but not that much - his calcium intake is probably fairly low.) Thanks.


I wouldn't supplement calcium tablets unless a calcium blood test showed calcium deficiency. If calcium is low in range perhaps you could improve your son's dietary calcium intake.

Thank you for your quick reply. I'll work on his dietary intake of calcium first.

Do a google search for "non-dairy sources of calcium". There are loads of links and lists available.

If it really worries you, you could do a finger-prick calcium blood test for £29. Doing it once a year is unlikely to break the bank for most people.

That's a good idea. Thanks very much.

Thanks, humanbean, I wasn't aware of that one.

Thanks for posting that Clutter. :)

It is an interesting read, yet I feel the hard science in that article re calcium supplementation just isn't there, it even says 'non-statistically significant' re a connection in the rise in dementia in calcium-taking women who had not had a stroke. It's hard to draw firm conclusions from these types of studies as you can't control every other aspect of what people in the study are eating and their genetics, there are simply too many variables. That doesn't mean there isn't a connection, just that a study like that doesn't prove it.

I do agree we'd all be far, FAR better getting the nutrients we need from food before reaching for the pill bottles. I think the trouble has come from the increase food processing over the past decades and the addition of so many additives. We've come such a long way adrift from growing our own organic veg/meat, and there is so much ill health, it's an epidemic. We're just so out of touch with our bodies and what they need (not helped by pharmaceutical companies out to make a fortune).

These days it's very easy to make claims about one or other vitamin/mineral as a sort of 'cure all' when in fact it's a much more complex picture, especially with an increased marketplace like the world wide web!

One can say a similar thing about various medicines, statins made the news again today. At the moments they're seen almost as a magic bullet for lowering cholesterol and preventing strokes/heart disease. I wonder if they will still be seen that way 10-20 years down the line! Today they were saying on the news that the Mediterranean diet is more effective than taking statins!

Also when dieticians talk about getting all nutrients from one's food, the question is what food, grown where? How long has it been stored? How far has it been transported before it reached your table? How did you cook it? Did you boil all the water soluble vitamins out of it?

I think we have a long, long way to go before we really understand the whole picture.

I think the Mediterranean Diet includes lots of sunshine too - so hopefully good levels of VitD. This according to Dr Sarah Myhill is the only benefit of a statin - the VitD effect. I have also read that the new generation of statins contain VitD - now there's a surprise :-) The anti-inflammatory effect of VitD is well reported ......

I live in Crete !

I think we could all benefit from the Mediterranean climate over here in cold, damp Britain! :D

A second day of sun! Cannot last.

When public health messages are given to the general population they are simplified to ensure the majority of the population understands them this is why slogans like "you can get all your nutrients from your food" are prevalent.

Only when you talk to individual health care professions in this case dieticians do you get more detailed information e.g. it is better to eat frozen veg than stuff picked a week ago as it contains more nutrients, it is better to microwave your veg then boil it as you use less water and decrease cooking time.

Even then some of them have strange ideas.

For example everyone who has had a vitamin D deficiency soon learns (if they have any interest why they need to take a maintenance dose for life ) that it is impossible for most humans on the planet to get all the vitamin D they need from food sources. This clearly doesn't fit into the "you can get all your nutrients from your food" slogan, yet some dieticians imply that food sources of vitamin D are enough.

I find the idea that microwaving vegetables is preferable to boiling or steaming or grilling to be peculiar in the extreme. I'd add that to the strange ideas you mentioned! Microwaving?! ( My neighbour has a 6-month old. She never breastfed but has been microwaving the milk since day 1. Ping!Ping!)

Me too! I think steaming them is far simpler and you get an even result that way, microwaving is far too prone to 'hot spots', even with fancy 'chaos' cooking. :D

Microwaving is preferred to boiling as the veg looses less nutrients. It's weird if you haven't done it in the same as stir frying veg is weird if you haven't done it. It's not preferred to steaming or grilling just to boiling.

You don't get hotspots if you do it properly and you don't need to add extra water in lots of cases.

I've met plenty of people now who warm up liquid - milk, tea, coffee in the microwave. As electric kettles take a couple of minutes I see no point in it but that is my preference.

I take magnesium occasionally to help with constipation and nighttime anxiety. I remember a conversation with a health store employee who said 'well if you're going to take magnesium you MUST take calcium with it'. That didn't sit right with me

Oh, never take advice from health store emplyees, they rarely know what they're talking about. One of them actually recommended I eat soy to 'cure' my thyroid problem!!!

Yep be informed. At the time I was too fog brained with lack of sleep to discuss it much but following your intuition is the safe bet 🌞

I think it works better the other way around. If you take calcium take magnesium. 2:1 ratio if I remember correctly. I believe that is more than an urban myth.

does anyone know about high calcium l had results of 2.7 range 2.2-2.6, corrected calcium 2.55 range 2.1-2.6 albumin 49, top of range 50 lm told high calcium is dangerous but haven't got a clue any help appreciated

If it was a one off then you need a retest, 2.7 is high but 2.55 is high normal so if your doctor only looks at the corrected result you will be deemed ok, another doctor may look at the 2.7 result and want further tests. If you have more than one high result then you need a parathyroid blood test done at the same time as calcium. If calcium and parathyroid are high then hyperparathyroidism is the likely cause and you will need to see an Endo experienced in this, many aren't so choose wisely.

Hypercalcemia only becomes a serious problem when it rises above 3 and if it was that high you would be fairly poorly, my calcium got to almost 2.9 but didn't cause me any major issues. Having said all that, if you are taking anything with calcium in it or you have a high calcium diet either of those could be the reason.

hi thanks for your reply, it was a private medichecks finger blood test so will do this again and double check the only thing with calcium in it is my d3 tablets 800iu daily from the docs and l don't have a high calcium diet my vitd wasn't all that high last time it was checked though its a bit of a minefield though hate going to the docs and mine most defo would not order any more tests on those results he wouldn't do the calcium test in the first place thanks for your advice though its appreciated

If you have high calcium you really shouldn't be taking supplements containing calcium. It isn't necessary and may be harmful. If you need to take vitamin D you have loads to choose from in lots of different strengths on Amazon and you can buy a year's worth for about £10 the last time I looked.

You would be better just taking a plain d3 without the calcium, unless you are calcium deficient ( which you definitely are not ) it's best to avoid the combined supplement. If you can persuade your GP to check your calcium at some stage it would probably be a more accurate reading, I use Medichecks but I'm not convinced of the accuracy of the results as the method of taking the blood plus time in transit must effect the sample to some degree.

As your corrected calcium is within range you don't need to worry but it's high normal so best to be aware of it and check now and again.

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