Calcium chaos

Imagine that I'm planning to build a wall of bricks. I start by throwing cement at a pile of bricks, hoping that it forms a nice, orderly brick wall.

Fat chance, you say.

I believe that is what appears to be emerging as the situation with calcium supplementation.

A recent study from New Zealand reported an experience with 1,471 postmenopausal women, mean age of 74 years, who were randomized to treatment with either calcium supplements or placebo. Calcium was supplied as calcium citrate (Citrical) to provide 1000 mg of (elemental) calcium per day (400 mg morning, 600 mg evening).

(Bolland MJ, Barber PA, Doughty RN et al. Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial. Brit Med J BMJ, doi:10.1136/bmj.39440.525752.BE; published 15 January 2008)

Over 5 years, women taking calcium had twice the risk of having a heart attack compared with women taking the placebo; women taking calcium had a 47 percent higher risk of having any one of three "events" (heart attack, stroke or sudden death) than women in the placebo group.

The findings of this study run counter to what we've been telling people all these years: Calcium supplementation, usually taken to halt deteriorating bone health and osteoporosis, modestly reduces blood pressure, reduces LDL and raises HDL cholesterol. At first blush, we might thereby presume that it also reduces cardiovascular events.

This study suggests that calcium supplementation does not result in reduction of cardiovascular events, perhaps even increases risk.

Certainly, this new finding will serve to confuse the public even more than it is already, particularly when it comes to strategies that modify risk for heart attack. However, this may make more sense once we stop and think for a moment.

Calcium supplementation inarguably slows, occasionally halts, calcium resorption from bone (through suppression of parathyroid hormone). Calcium also accumulates as part of atherosclerotic plaque in coronary and other arteries.

How does oral calcium know where to go--bones, not arteries or kidneys, in addition to serving all its other crucial functions?

Keep in mind that, in many roles, calcium is passive, something that responds to control exerted by some other factor. Vitamin D is that factor. Vitamin D controls the absorption of calcium in the intestinal tract (calcium aborption quadruples when vitamin D is restored to normal), it controls whether calcium is deposited in bone or extracted from arteries. It is the master control over the fate of calcium. Calcium just goes along for the ride.

Bone and arterial health do indeed intersect via calcium, but not through calcium supplementation. Instead, the control exerted by vitamin D (and vitamin K2, another conversation) connects the seemingly unrelated processes.

At what calcium dose threshold do the benefits stop and the adverse effects begin? That remains unanswered, particularly in light of this new study. However, this study calls into serious question the wisdom of supplementing calcium at a dose of 1000 mg, particularly when taken without normalization of vitamin D.

Calcium is therefore emerging as an important player in artery health. But just taking calcium makes no more sense than our brick wall and cement analogy. You might regard vitamin D as the mason that skillfully lays down both brick and cement in a neat, orderly way.

Comments (30) -

  • Anne

    1/23/2008 7:47:00 AM |

    Dear Dr Davis,

    Sometimes I think I must be living in the Matrix - I thought this article so interesting as I have been prescribed calcium supplements for osteoporosis, but just a few weeks ago I had to stop taking them because I discovered they were the cause of severe diarrhoea I had been having for nearly a year. Stopping the calcium supplements halted the diarrhoea straight away, trying it again, even a different make, brought it back even on low dose. Anyway, it was just then that I read a lot about vitamin D3 on your blog and Dr Eades, just at that very time, so I upped my D3 intake to 5,000iu in the hopes it will help me absorb as much of my dietary calcium as possible. I cannot take dairy products so I get my calcium from leafy green veggies, nuts, seeds and fish. And now you wrote on your blog to look at vitamin D3 for aortic valves (I'm the one with bicuspid aortic valve) too. The Matrix ! Or I've found the best doctors on the internet Smile

    all the best,

  • Anonymous

    1/23/2008 5:23:00 PM |

    I'm taking Vit D3 in gel form for my bones, heart, and to help prevent cancer, until it warms up here so I can get some sun. I'll be getting plenty of direct sun while gardening and bike riding, but the rest of the time outside, I'll sit in the the shade so I won't get too much UVA, since my family had a few skin cancers (caught early).

    I'm going to look for natto when I finally make it to the Asian store. I've heard it tastes pretty bad for people that have never eaten it, so I'll have to try to mix it in with something else probably. I've also read that some people compare it to blue cheese, so maybe I'll start with blue cheese recipes to try to mellow the natto taste.


  • Red Sphynx

    1/23/2008 6:50:00 PM |

    Granted, calcium supplements leave a lot to be desired.

    But this article didn't cast any light on the problem.  Read Sandy Szwarc' excellent Fisking of this study over at JunkFoodScience.

    Adam Becker Sr

  • Anonymous

    1/23/2008 8:53:00 PM |

    Doesn't calcium compete with magnesium for absorption from the gut?  In which case, supplemental magnesium in addition to the calcium would be indicated

  • Anonymous

    1/24/2008 12:49:00 AM |

    I am so confused about this whole chotesterol/ heart attack risk argument. I've been reading your blog for months now and follow everything you say because it sounds like it all makes great sense. So whats the problem? We keep hearing more and more that total cholesterol, as was once thought, is not a very good indcator of impending heart attack. So how come Dr.William Castelli, the one time director of the famous Framingham Study says in over 60 years following thousands of people, they have NEVER had a heart attack in ANYONE with a total cholesterol below 150 regardless of what the HDL may be? If that doesn't indicate that total cholesterol CAN be a strong indicator I don't know what can. I understand if your cholesterol is higher than 150 this may not tell you anything, but for those of us below doesn't it? Or does no heart attacks in a 60 year period with thousands of people tell us nothing?

  • Dr. Davis

    1/24/2008 2:44:00 AM |

    I do not agree with Dr. Castelli's observation. I have seen MANY heart attacks with total cholesterols <150 mg/dl. I do not understand the discrepancy.

    For instance, an HDL of 23 mg/dl--very high risk--can easily be concealed within a low total cholesterol, as can smoking, diabetes, and Lp(a).

  • Peter

    1/24/2008 9:05:00 AM |

    Anonymous, even the most cursory glance at any of the aggressive LDL-C lowering trials will give you the information about the accuracy of Dr Castelli's statement. Let's not be too explicit.


  • donnyrosart

    1/24/2008 1:33:00 PM |

    It looks like going into the study, the authors suspected the opposite (calcium prevents heart disease) was true. They mention speculation that calcium supplementation might be heart healthy by increasing malabsorption of fat, and quote a study where calcium supplementation doubled fecal fat and bile. Personally, I try to eat things I'd like to absorb.
    The first study they reference to (I think it's their own study) showed calcium supplementation increased Hdl, and decreased ldl, but had no effect on triglycerides. If ldl decreases, but triglycerides remain the same, does that suggest anything about ldl particle size?
    Really like your blog.

  • Dr. Davis

    1/24/2008 4:19:00 PM |

    Good question.

    I've not looked specifically for a LDL size effect from calcium, nor am I aware of any specific literature to this effect. However, I do believe that many of us are trending towards less and less calcium supplementation, particularly in light of vit D supplementation.

  • Anonymous

    1/24/2008 7:59:00 PM |

    I apologise maybe I worded my question incorrectly. Dr. Castelli doesn't claim that if you have a total cholesterol under 150 you will not have a heart attack, he says in The Framingham study ( involving 3 generations and over 10,000 people ) there has never been one. I suppose we could blow this off and claim he's lying ( I doubt it ) or try to learn something from it. Thats a VERY large long lasting study and once again he has said "under 150 REGARDLESS of HDL score" there HAS to be a reason for this, I was just wondering if anyone had a guess.

  • brittany lady

    1/24/2008 10:59:00 PM |

    This now has me totally confused.  My doctor recommended I take 1,000 mg. of Calcium in supplement form every day, and to make sure I get 800 mg. of Vitamin D.  I have done so faithfully plus drinking about 10 oz. of calcium added Lactaid fat free milk. I also learned after an x-ray, stress test and heart imaging that I have calcification at the base of my aorta, but my heart is not enlarged.  This has happened since 1999, and I have only been taking Vitamin D for the past year and a half. Now I wonder if large doses of Calcium before having my vitamin D levels tested might have caused this. On another note, I had very high triglycerides and started taking 2000 mg. of fish oil capsules daily.  My triglycerides dropped from 375 to 160 in 6 months.  That might be a solution to someone with these concerns.

  • Anne

    1/25/2008 8:23:00 AM |

    Since being diagnosed with osteoporosis last year I have done a lot of research on it and on various therapies. I am, btw, only 54 so it was a big shock. Anyway, looking at things logically, there is no way that someone my age would have got osteoporosis from lack of calcium, so why do they prescribe it ? It seems based on research done on elderly ladies in nursing homes. I've got osteoporosis because of health issues when I was younger yet, I was still told the usual to take 1000mg calcium and 800iu vitamin D. I refused bisphosphonates and have been prescribed Strontium Ranelate instead. I hope Strontium doesn't cause calcification, I don't think they know enough about it so I feel rather a guinea pig. Now that I can't tolerate calcium and have stopped taking it and upped the Vitamin D3 to 5000iu I feel more confident that this will help not only my bones but also my heart health. I also take 2,000mg of fish triglycerides are currently 0.6 (53).


  • Anne

    1/25/2008 1:39:00 PM |

    Something else to make one realise that calcium may not be as important as we have been told - if you look at countries in Africa where some people have sub-optimal diets and low in calcium, you usually don't often find osteoporosis ! I would hazard a guess that the reason they don't get osteoporosis is because they have plenty of Vitamin D from the sunshine and they probably do a lot of physical work.


  • Dr. Davis

    1/25/2008 1:51:00 PM |

    Great thought.

    I am impressed that many of the "holes" in our thinking about health and nutrients is filling in with greater understanding of the role of vitamin D.

  • Rick

    1/25/2008 5:19:00 PM |

    Dr. Castelli also made the following observation:

    "For example, in Framingham, Mass, the more saturated fat one ate, the more cholesterol one ate, the more calories one ate, the lower the person’s serum cholesterol."

    For Dr. Eades's typically insightful take on the issue, go here:

    and here:

  • Dr. Davis

    1/26/2008 5:05:00 AM |

    I couldn't agree more.

    Cholesterol (total and LDL) are lousy predictors of heart disease. They are, indeed, factors. But in the long list of factors causing heart disease, cholesterol is way down.

    But cholesterol is, no doubt, the most profitable. Revenues for statin drugs topped $27 billion last year.

  • Anonymous

    1/26/2008 3:05:00 PM |

    Great articles Rick, read them both and found them quite interesting however a little disappointed neither had anything to do with why after 60 years and following over 10,000 people NOT ONE of them with a total cholesterol under 150 ever had a heart attack. I eat low carb, loved Taubes book explaining the myths about eating fat, big proponent of Track your plaque and think Dr. Davis is brilliant and well ahead of his time. And yet either we think Dr. Castelli is a liar or anybody with ANY interest in preventive cardiology would want to know why no heart attacks in anyone with tot cholesterol under 150 in over 60 years in such a large group of people. My god we hear all the time about the stunning results of the HATS Trial which included a grand total of 161 people.

  • MAC

    1/26/2008 5:38:00 PM |

    Dr. Davis,
        Found this study while perusing Science daily today. Not sure how or if this intersects at all with the good results you get with Vit D.

    Vitamin D Deficiency May be a Sympton of Disease: Supplementations may make it worse:

    "Low blood levels of vitamin D have long been associated with disease, and the assumption has been that vitamin D supplements may protect against disease. However, this new research demonstrates that ingested vitamin D is immunosuppressive and that low blood levels of vitamin D may be actually a result of the disease process. Supplementation may make the disease worse."

  • Dr. Davis

    1/27/2008 2:18:00 AM |

    It refers to the so-called "Marshall Protocol." Having read his arguments, he mixes science with conjecture and enormous leaps of speculation, all with zero experience in real, live humans. (He's a "bench" researcher with experience that doesn't extend beyond mice and cell cultures.)

    It reminds me an awful lot of the pseudo-scientific tangent that misled Linus Pauling and Mathias Rath.

  • Rick

    1/27/2008 7:40:00 AM |


    No need to be disappointed.  Here's the relevance.  Dr. Eades quoted Dr. Kannel, who preceded Castelli as director of the Framinham study as saying:

    " is not possible to select a critical lipid value that separates potential CHD candidates from the rest of the population."

    That appears to contradict the implications of Castelli's quote.

    Dr. Eades also made the case that sometimes the pronouncement of the researchers is not supported by the evidence.

    What percent of the population had cholesterol lower than 150?  What was their age distribution?  These would be important things to know.

    In looking at a graph of the distribution, it appears that less than 5% of the population were in that category.  

    BTW, can you you provide a citation for your quote of Dr. Castelli?  Thanks.

  • Stan

    1/27/2008 3:32:00 PM |


    Castelli said that there was no heart attack at all in the sub-population below 150mg/dl of cholesterol, and he said also
    that, quote:

    "For example, in Framingham, Mass, the more saturated fat one ate, the more cholesterol one ate, the more calories one ate, the lower the person’s serum cholesterol."

    This is a speculation but one possible explanation behind those two seemingly contradictory informations is that the
    subpopulation of people who had naturally low cholesterol in Framingham, were all young and/or  were all eating more animal fat and less carbohydrates than the other groups!  Younger people are more active and eat more calories too. Both factors (young age and a higher animal fat lower carbohydrate nutrition) tend to associate with low cholesterol
    and are simultanously cardioprotective.

    Is it improbable? I dont' think so. Dr. Davis's own results on vitamin D3 and essential fatty acids supplementation (naturally present in animal food, dairy, eggs, meat and fish!) also seem to point in the same direction.

    It would also fit another observation: I remember some published data on Masai population who also have or had very low total cholesterol (I think about 160 mg/dl on average), follow a high fat low carbohydrate nutrition and have very little heart disease!

    Stan (Heretic)

  • Anonymous

    1/28/2008 3:38:00 PM |, Rick try this one but any search on google brings many citataions.

  • Anonymous

    1/28/2008 3:41:00 PM |

    Rick heres another better one.

  • Rick

    1/29/2008 12:32:00 AM |


    Thanks for the links, but the first one is the link I gave you, and the second is truncated.  

    If it's the article by the chiropracter, I've already seen that, but was hoping for  a primary source so I could read the context.  I've done a fair amount of googling but haven't been able to find it.

    Your quote speaks of 60 years of research, yet the artcle you cite (at least I think it's the same artcle) speaks of 40 years and the Framingham website is proudly celebrating 50 years of research.

    This is not to nitpick but it does make me wonder if this isn't one of those internet quotes that takes on a life of its own.

    I agree with you that it is confusing because so much of what I have read, along with my own experience renders his observation, whether true or not, meaningless.

  • Anonymous

    1/29/2008 12:51:00 AM |
    This article explains Dr. Castelli's position well.

  • Anonymous

    1/29/2008 12:55:00 AM |
    Read this one Rick.

  • Anonymous

    1/30/2008 3:07:00 PM |

    The Framingham Study was begun in 1948. That seems to be the one point that is a fact.

  • Rick

    1/30/2008 7:14:00 PM |

    Thanks for the link.  That is one of the articles I'd already seen. ( Not to put too fine a point on it, but he does refer to 40 years, not 60 as in your quote.)

    The data I've seen confirms his statement.  People whose TC was below 150 didn't evidence CHD.  But, as I mentioned above, the number of those people was extremely small, less than 5% of the population. It may be true the nobody who's run a sub 2:10 marathon has suffered a heart attack, but so what?

    For the vast majority of the population in the study, those between 150 and 370, some did have CHD, some didn't.  The correlation was not strong except on the edges.  

    So what can we take away from this?  Get your TC below 150 and you're immune from CHD?  The same research shows correlation with low levels of TC and all cause mortality.  So choose your poison.

    And if, despite your best efforts, your numbers creep up above 150, are all bets off?  My TC over the years, has ranged from 140 to 180, most recently 160, yet my plaque burden put me in the 50th percentile for my peer group.  So the importance of Dr. Castelli's observation is lost on me.

    As pointed out by Dr. Davis, and many others, total cholesterol alone is not a very useful indicator. Check out the post on the Vytorin study. Those whose cholesterol dropped the most experienced a greater increase in plaque.

    So, while Castelli's statement is based in fact, there is a lot of room for interpretation.  And most of the rest of what is attributed to him in that article is speculation.

    Yes, Framingham was begun in 1948, but I doubt the data is available instantaneously.

  • Anonymous

    6/4/2008 1:31:00 PM |

    My sister and I got in argument at a picnic about whether calcium supplements are a good idea.  Afterward she sent me an article in favor, and I sent her one against.  Then I realized you wrote both articles!

  • ccruby

    8/17/2008 1:30:00 AM |

    Mayo Clinic diagnosed me with fluid around my heart.  I could feel it sloshing around.  Stopped calcium/mag and estrogen supplements and I could no longer feel it; I also kept telling it to go away.  Went back a couple of months later for MRI--Mayo said I had fat around my heart.  I know the original diagnosis was correct.