“I heard that calcium causes heart disease! I’m emptying all my yogurt on my lawn for those cats that brawl outside my window at 4 AM to eat.”
“My bones are fine! I’m so young, and I wear a weighted vest to school. I don’t need calcium!”
“I get all my calcium from broccoli and spinach! Screw milk!”
“Uh…will dairy products make me lose weight?”
I grouped all these questions together to form this week’s quickie. If you think you could give two zits about calcium, and it certainly isn’t a concern of yours that ranks higher than wondering how Snookie’s new maternity line of clothing is panning out, then you among all people should read on to find out more about this super awesome and controversial mineral.
Whatever, I know about calcium already. It’s in my bones. I’m fine.
You’re right; calcium is very key for your bones. It’s the most abundant mineral in your body, and 99% of it is stored in your skeleton! But did you know that you also need calcium for things like muscle contraction, nerve transmission, and hormone secretion?
Also, don’t be so quick to assume your bones are awesome. There are several factors that influence your bone health, including dietary levels of calcium, magnesium, vitamin D, your body weight, and exercise. You only have until you’re about 30 to 35 to build up your peak bone mass. After that, the rate of bone loss exceeds the rate of bone building, so you start to slowly lose bone mass every year. That doesn’t mean that all those factors that can build bone mass aren’t important any more; it’s just now they are aimed to maintain the density you have, rather than build up to a higher peak from which to fall.
Wow, what a downer. So if I’m younger than 35, I should pound supplements, and if I’m 35 or up, I should jump off a bridge?
Post-35 or not, jumping off something other than a bridge is actually a good idea (try the ground or a curb!) Jumping in general puts impact on your skeleton, which makes the calcium you eat actually get integrated into your bones. No matter what your calcium intake is, if you don’t stimulate your bones to get denser through impact or weight-bearing activity, you’re not helping your skeletal situation like you think you are.
“Weight-bearing?” Who talks like that? And what do you even mean? I “bear” myself, don’t I?
Bearing weight is essentially that — carrying a weight or using gravity as a force to help stimulate your bones to say, “hmmm, maybe I need to beef up my foundation.” And no, if you weigh less than 130 pounds, you aren’t bearing enough weight to stimulate your bones, at least by walking; weighing less than a buck 30 is an independent risk factor for osteoporosis, so you guys have to make especially sure you get some impact or weight lifting into your lives.
So I should pound supplements of calcium while doing jump lunges and giving my refrigerator a piggy back ride?
Yes, have fun with that. But as for pounding supplements, maybe not….
Yeah, that’s right! I forgot! Websites and my next-door neighbor told me that calcium gives me heart disease!
A few studies that have (recent-ish-ly) hit the press reported that calcium supplements modestly increased the risk of heart attacks (1). These studies were were attacked for several flaws in the methods (2) and were not randomized controlled trials. But they caused drama, despite several studies, including randomized controlled trials, finding no increase in incidence or mortality from cardiovascular disease with calcium supplementation (3).
So when the “calcium sucks” research stormed the press, bat guano hit the proverbial lidless blender in your Anakiwa Blue #3-hued bedroom. (Gyah!) First, what about people who are at risk for osteoporosis?! Should they stop taking supplements and just start breaking their fingers when they type too hard? Secondly, cardiologists remain skeptical. The mechanism that the researchers of the heart-attack study suggested doesn’t totally jibe with the current understanding of the pathophysiology of heart disease (4).
So I don’t care about the controversy or the research. I care about ME. What should I do?
1. At this point there is no evidence confirming or refuting the suggestion that calcium supplementation increases the risk of heart attacks.
2. The associations that were found were NOT from dietary calcium, but from supplements. SO it’s a good idea to get your calcium from foods! In a couple of days I’ll go over the best foods to get it from and how much you need.
3. If you have low dietary intakes and for some reason do not want to increase your intake of calcium, or you have or are at risk for osteoporosis, supplements may still be warranted. It’s cause for pause until it gets straightened out, but the risks and benefits should be weighed out on a situational basis. If you are going to take supplements, cut the supplement in half and make sure you take it with food.
4. Vitamin D is something that you also need for bones, and it is something most of us don’t get enough of. More on that in a few days…
Oh yeah, hey! You didn’t answer the other questions!! You missed a week of posting and now you leave us hanging?
I will in a few days! I just got all caught up in all the current calcium research to answer the heart disease question thoroughly. Plus, I’ve been told to make these shorter by more people than just my mom.
MS, RD, PhD
Footnotes and SUPER INTERESTING Details!!
1. The most splashy studies were a meta-analysis, which looked at the results from several studies, and a prospective study, which had no intervention but followed people for years, asked them how much calcium they took, and watched to see what happened.
2. One complaint of the meta-analysis was that it evaluated studies for outcomes that the studies were not originally designed to test. Another complaint, or shade of doubt, cast on the meta-analysis was that the researchers reported a significant overall increased risk, even though none of the individual studies showed a significant effect of calcium supplements on heart attacks, even the largest and best-designed trial. Also, there was no effect of a personal use of calcium supplements on heart outcomes, only an effect when the supplements were administered by researchers. Finally, none of the studies in the original analysis included Vitamin D supplementation in them, which is now decidedly healthy for bone health (the investigated outcome of many of the studies included in the meta-analysis).
The prospective “German” study published this year in the journal Heart counted events rather than people with events as significant. Also, the reports of calcium intake for the studies were self-report; people can have poor memories of their own food intake, especially when given a checklist that has them estimate weekly servings. (Furthermore, people have been known to lie…it’s true!) Also, the number of calcium takers who had heart attacks was small, which caused people to question the conclusions. Finally, there was no “dose-response” relationship; people who took more calcium didn’t show more heart attacks or signs of heart disease.
3. I actually take issue with the research regarding calcium supplements on both sides of the argument. The researchers, and people who take supplements, count one daily supplement as adequate. In the clinical trial that found no increased risk of heart incidents in supplement takers, the subjects were given 1000 mgs of calcium at one time. Both of these assessments of calcium absorption are flawed. As you increase the amount of calcium you ingest, your body absorbs it less efficiently. The optimal level of calcium to take in at one time is around 500 mg, and if you ingest more than that, you probably absorb like only 300 mg. So not only were the subjects not getting the optimal total dose of calcium, but they were getting a huge bolus at one time. One ramification of the large dosage is the blocking of absorption of other minerals like iron that are similar in charge and size to calcium and therefore use the same receptor sites to get into the body. This calls into question the assessment of calcium intake on both sides of this risk fence.
4. The researchers of the heart disease and calcium supplement epidemiological study suggest that excess calcium could be deposited in the artery walls which contribute to plaque formation. But the calcium in the plaque is a response to injury to the artery wall, which could happen to anyone, supplement or no supplement. So, further research into this argument is needed.
Sources—Seriously, check them out! Here for you to think for yourself!
The Splashy Meta-Analysis:
Bolland, M.J., Avenell, A., Baron, J.A., Grey, A., MacLennan, G.S., Gamble, G.D., Reid, I.R. (2010). Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. British Medical Journal, 341, c3691.
Below is the meta-analysis, redone, because people yelled at the authors for including studies that were not designed with the cardiovascular endpoint in mind. Also, the studies included in the first meta-analysis did not include Vitamin D, even though this has been shown to be very important for bone development. So the authors included a new dataset from the Women’s Health Initiative to answer the vitamin D question, threw in some more studies, and redid the meta-analysis.
Bolland, M.J., Grey, A., Avenell, A., Gamble, G.D., Reid, I.R. (2011). Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women’s Health Initiative limited access dataset and meta-analysis. British Medical Journal, 342, d2040.
The German Prospective Trial:
Li, K., Kaaks, R., Linseisen, J., Rohrmann, S. (2012). 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 (EPIC-Heidelberg). Heart, 98, 920-925.
Some of the other side. Here’s a long-term follow up of a placebo-controlled trial. No difference in all-cause mortality, vascular disease mortality, cancer mortality, and cancer incidence in people who took Vitamin D, Calcium, both, or neither.
Avenell, A., MacLennan, G.S., Jenkison, D.J., McPherson, G.C., McDonald, A.M., Pant, P.R., Grant, A.M., Campbell, M.K., Anderson, F.H., Cooper, C., Francis, R.M., Gillespie, W.J., Robinson, C.M., Torgerson, D.J., Wallace, & W.A. (2012). Long-term follow-up for mortality and cancer in a randomized placebo-controlled trial of vitamin D(3) and/or calcium (RECORD trial). Journal of Clinical Endocrinology & Metabolism, 97(2), 614-22.
Here’s an excellent systematic review finding that Vitamin D supplementation in moderate to high doses may reduce the risk of heart disease but calcium supplements had minimal effects.
Wang, L., Manson, J.E., Song, Y., & Sesso, H.D. (2010). Systematic review: Vitamin D and calcium supplementation in prevention of cardiovascular events. Annals of Internal Medicine, 152(5), 315-23.
A nice review article:
Meier, C., Kraenzlin, M.E. (2011). Calcium supplementation, osteoporosis, and cardiovascular disease. Swiss Medical Weekly, 141, 13260.