tag:theconversation.com,2011:/au/topics/calcium-supplements-3117/articlesCalcium supplements – The Conversation2016-05-17T10:04:47Ztag:theconversation.com,2011:article/592462016-05-17T10:04:47Z2016-05-17T10:04:47ZNanoparticles in baby formula: should parents be worried?<figure><img src="https://images.theconversation.com/files/122746/original/image-20160516-15906-1ymu3xg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What's in the bottle is good for me, right?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/21524179@N08/3669555322">nerissa's ring</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>There’s a lot of stuff you’d expect to find in baby formula: proteins, carbs, vitamins, essential minerals. But parents probably wouldn’t anticipate finding extremely small, needle-like particles. Yet this is exactly what a team of scientists here at Arizona State University <a href="http://www.foe.org/projects/food-and-technology/nanotechnology/baby-formula">recently discovered</a>.</p>
<p>The research, commissioned and published by Friends of the Earth (<a href="http://www.foe.org/">FoE</a>) – an environmental advocacy group – analyzed six commonly available off-the-shelf baby formulas (liquid and powder) and found nanometer-scale needle-like particles in three of them. The particles were made of hydroxyapatite – a poorly soluble calcium-rich mineral. Manufacturers use it to regulate acidity in some foods, and it’s also available as a dietary supplement.</p>
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<a href="https://images.theconversation.com/files/122339/original/image-20160512-5088-12g9emr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122339/original/image-20160512-5088-12g9emr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122339/original/image-20160512-5088-12g9emr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=596&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122339/original/image-20160512-5088-12g9emr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=596&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122339/original/image-20160512-5088-12g9emr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=596&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122339/original/image-20160512-5088-12g9emr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=748&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122339/original/image-20160512-5088-12g9emr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=748&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122339/original/image-20160512-5088-12g9emr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=748&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Needle-like particles of hydroxyapatite found in infant formula by ASU researchers.</span>
<span class="attribution"><span class="source">Westerhoff and Schoepf/ASU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Looking at these particles at super-high magnification, it’s hard not to feel a little anxious about feeding them to a baby. They appear sharp and dangerous – not the sort of thing that has any place around infants. And they are “nanoparticles” – a family of ultra-small particles that have been <a href="http://dx.doi.org/10.1038/444267a">raising safety concerns within the scientific community</a> and elsewhere for some years.</p>
<p>For all these reasons, questions like “should infants be ingesting them?” make a lot of sense. However, as is so often the case, the answers are not quite so straightforward.</p>
<h2>What are these tiny needles?</h2>
<p>Calcium is an essential part of a growing infant’s diet, and is a <a href="http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=107.100">legally required component</a> in formula. But not necessarily in the form of hydroxyapatite nanoparticles.</p>
<p>Hydroxyapatite is a tough, durable mineral. It’s naturally made in our bodies as an essential part of bones and teeth – <a href="https://en.wikipedia.org/wiki/Hydroxylapatite">it’s what makes them so strong</a>. So it’s tempting to assume the substance is safe to eat. But just because our bones and teeth are made of the mineral doesn’t automatically make it safe to ingest outright.</p>
<p>The issue here is what the hydroxyapatite in formula might do before it’s digested, dissolved and reconstituted inside babies’ bodies. The size and shape of the particles ingested has a lot to do with how they behave within a living system.</p>
<p>Size and shape can make a difference between <a href="http://www.webmd.com/news/breaking-news/food-additives/20150723/nanoparticles-food-additives">safe and unsafe</a> when it comes to particles in our food. Small particles aren’t necessarily bad. But they can potentially get to parts of our body that larger ones can’t reach. Think through the gut wall, into the bloodstream, and into organs and cells. Ingested nanoscale particles may be able to <a href="http://dx.doi.org/10.1080/02652030701744538">interfere with cells</a> – even beneficial gut microbes – in ways that larger particles don’t.</p>
<p>These possibilities don’t necessarily make nanoparticles harmful. Our bodies are pretty well adapted to handling naturally occurring nanoscale particles – you probably ate some last time you had burnt toast (carbon nanoparticles), or poorly washed vegetables (clay nanoparticles from the soil). And of course, how much of a material we’re exposed to is at least as important as how potentially hazardous it is. </p>
<p>Yet there’s a lot we still don’t know about the safety of intentionally engineered nanoparticles in food. Toxicologists have <a href="http://dx.doi.org/10.1289%2Fehp.7339">started paying close attention to such particles</a>, just in case their tiny size makes them more harmful than otherwise expected.</p>
<p>So where does this leave us with nanoscale hydroxyapatite needles in infant formula?</p>
<h2>What do regulators know about nano-safety?</h2>
<p>Putting particle size to one side for a moment, hydroxyapatite is classified by the US Food and Drug Administration (FDA) as “Generally Regarded As Safe.” That means it considers the material safe for use in food products – at least in a non-nano form. However, <a href="http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/ucm300661.htm">the agency has raised concerns</a> that nanoscale versions of food ingredients may not be as safe as their larger counterparts. </p>
<p>Some manufacturers may be interested in the potential benefits of “nanosizing” – such as increasing the uptake of vitamins and minerals, or altering the physical, textural and sensory properties of foods. But because decreasing particle size may also affect product safety, the FDA indicates that intentionally nanosizing already regulated food ingredients could require regulatory reevaluation.</p>
<p>In other words, even though non-nanoscale hydroxyapatite is “Generally Regarded As Safe,” according to the FDA, the safety of any nanoscale form of the substance would need to be reevaluated before being added to food products.</p>
<p>Despite this size-safety relationship, the FDA confirmed to me that the agency is unaware of <em>any</em> food substance intentionally engineered at the nanoscale that has enough generally available safety data to determine it should be “Generally Regarded As Safe.”</p>
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<span class="caption">Hydroxyapatite nanoparticles may have different health effects from larger versions of the mineral.</span>
<span class="attribution"><span class="source">Westerhoff and Schoepf/ASU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Casting further uncertainty on the use of nanoscale hydroxyapatite in food, a 2015 report from the European Scientific Committee on Consumer Safety (SCCS) suggests there <a href="http://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_191.pdf">may be some cause for concern</a> when it comes to this particular nanomaterial. </p>
<p>Prompted by the use of nanoscale hydroxyapatite in dental products to strengthen teeth (which they consider “cosmetic products”), the SCCS reviewed published research on the material’s potential to cause harm. Their conclusion?</p>
<blockquote>
<p>The available information indicates that nano-hydroxyapatite in needle-shaped form is of concern in relation to potential toxicity. Therefore, needle-shaped nano-hydroxyapatite should not be used in cosmetic products.</p>
</blockquote>
<p>This recommendation was based on a handful of studies, none of which involved exposing people to the substance. Researchers injected hydroxyapatite needles directly into the bloodstream of rats. Others exposed cells outside the body to the material and observed the effects. In each case, there were tantalizing hints that the small particles interfered in some way with normal biological functions. But the results were insufficient to indicate whether the effects were meaningful in people.</p>
<p>Importantly, these studies didn’t consider what happens when particles like this end up in the digestive system, including the stomach.</p>
<h2>So what happens when a baby eats them?</h2>
<p>The good news is that, according to preliminary studies from ASU researchers, hydroxyapatite needles don’t last long in the digestive system.</p>
<p>This research is still being reviewed for publication. But early indications are that as soon as the needle-like nanoparticles hit the highly acidic fluid in the stomach, they begin to dissolve. So fast in fact, that by the time they leave the stomach – an exceedingly hostile environment – they are no longer the nanoparticles they started out as.</p>
<p>These findings make sense since we know hydroxyapatite dissolves in acids, and small particles typically dissolve faster than larger ones. So maybe nanoscale hydroxyapatite needles in food are safer than they sound.</p>
<p>This doesn’t mean that the nano-needles are completely off the hook, as some of them may get past the stomach intact and reach more vulnerable parts of the gut. But the findings do suggest these ultra-small needle-like particles could be an effective source of dietary calcium – possibly more so than larger or less needle-like particles that may not dissolve as quickly.</p>
<p>Intriguingly, recent research has indicated that calcium phosphate nanoparticles form naturally in our stomachs and go on to be <a href="http://doi.org/10.1038/nnano.2015.19">an important part of our immune system</a>. It’s possible that rapidly dissolving hydroxyapatite nano-needles are actually a boon, providing raw material for these natural and essential nanoparticles.</p>
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<a href="https://images.theconversation.com/files/122747/original/image-20160516-15926-1q2xeo4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122747/original/image-20160516-15926-1q2xeo4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122747/original/image-20160516-15926-1q2xeo4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122747/original/image-20160516-15926-1q2xeo4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122747/original/image-20160516-15926-1q2xeo4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122747/original/image-20160516-15926-1q2xeo4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122747/original/image-20160516-15926-1q2xeo4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122747/original/image-20160516-15926-1q2xeo4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The formula’s safe, but begs other questions.</span>
<span class="attribution"><span class="source">Andrew Maynard</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>Tempest in a baby bottle</h2>
<p>And yet, even if these needle-like hydroxyapatite nanoparticles in infant formula are ultimately a good thing, the FoE report raises a number of unresolved questions. Did the manufacturers knowingly add the nanoparticles to their products? How are they and the FDA ensuring the products’ safety? Do consumers have a right to know when they’re feeding their babies nanoparticles?</p>
<p>Whether the manufacturers knowingly added these particles to their formula is not clear. At this point, it’s not even clear why they might have been added, as hydroxyapatite does not appear to be a substantial source of calcium in most formula. (Calcium in formula can come from a number of sources, including milk solids, calcium carbonate and calcium chloride.) If the nanoparticles’ inclusion was intentional, though, current FDA guidelines suggest that the regulator wouldn’t consider the material safe by default, and should be subject to further evaluation.</p>
<p>Certainly, from the data presented, these particles – so uniform in size and shape – look like they were intentionally manufactured to be nanoscale and needle-like. It’s possible they were supplied to the various manufacturers without any indication of their “nano-ness.” This doesn’t absolve the manufacturers of responsibility. But it does suggest that greater scrutiny and accountability is needed in the supply chain for food ingredients.</p>
<p>And regardless of the benefits and risks of nanoparticles in infant formula, parents have a right to know what’s in the products they’re feeding their children. In Europe, food ingredients must be <a href="http://ec.europa.eu/food/safety/docs/labelling_legislation_infographic_food_labelling_rules_2014_en.pdf">legally labeled if they are nanoscale</a>. In the U.S., there is no such requirement, leaving American parents to feel somewhat left in the dark by producers, the FDA and policy makers.</p>
<p>Given the state of science on nanoscale hydroxyapatite in foods, this is as much an issue of trust as it is safety. The FoE report may exaggerate the possible risks, and raise concerns where few are justified. Yet it’s hard to avoid the reality that, if manufacturers are adding nanoparticles to what we feed our children, we need to know more about how to ensure their safety and benefits. How else can we enable informed decisions? </p>
<p>Luckily, current research suggests hydroxyapatite nanoparticles in formula are most likely safe, and arguably, even beneficial. But given how high the stakes are, safety here should not, and indeed cannot, be taken for granted.</p><img src="https://counter.theconversation.com/content/59246/count.gif" alt="The Conversation" width="1" height="1" />
<h4 class="border">Disclosure</h4><p class="fine-print"><em><span>Andrew Maynard receives funding support from the Center for Research on Ingredients Risk (CRIS) at Michigan State University. He is also on the Board of Trustees of the International Life Sciences Association North America. He was an independent reviewer on the Friends of the Earth report on nanoparticles in infant formula</span></em></p>Microscopic needle-like particles don’t seem like something you’d want to feed a baby. Whether safe or not, the way we deal with nanoscale food additives leaves plenty of other questions.Andrew Maynard, Director, Risk Innovation Lab, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/127112013-03-21T22:45:29Z2013-03-21T22:45:29ZCalcium confusion: scientists divided over supplements<figure><img src="https://images.theconversation.com/files/21489/original/26k7y7bj-1363753775.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's conflicting evidence about both the efficacy and the safety of taking calcium supplements.</span> <span class="attribution"><span class="source">it thatswitch/Flickr</span></span></figcaption></figure><p>A clash between supporters and detractors of calcium supplements for better bone health is leading to conflicting headlines, leaving the public unsure about whom to believe.</p>
<p>Osteoporosis is estimated to cost the Australian economy more than $7 billion a year. It’s a condition that <a href="http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4364.0.55.001chapter3102011-12">affects</a> around 700,000 Australians, the vast majority of whom are women. In 2009-10, nearly 7,000 Australians were hospitalised as a result of osteoporosis.</p>
<p>It’s accepted that limited exposure to sunlight resulting in low <a href="http://www.nrv.gov.au/nutrients/vitamin%20d.htm">vitamin D</a> intake is a risk factor contributing to osteoporosis, and the <a href="http://www.nhmrc.gov.au/">National Health and Medical Research Council</a> (NHMRC) says the combination of calcium and vitamin D can help reduce the chance of breaking bones.</p>
<p>But scientists differ on where people should get their calcium.</p>
<p>Last month, independent health experts from the US <a href="http://www.ahrq.gov/professionals/clinicians-providers/guidelines-recommendations/uspstfix.html">Preventive Services Task Force</a> said adding vitamin D and calcium to a healthy diet does not lower risk of fractures in post-menopausal women, and that for younger women and men, the studies were too inconclusive to support regular use of supplements. </p>
<p>This is despite a <a href="http://www.nhlbi.nih.gov/whi/">Women’s Health Initiative</a> study on the benefits and risks of daily calcium and low-dose vitamin D supplements finding they led to a 12% reduction in hip fractures for women aged 50-79, and a 21% reduction for women aged over 60. Those women with intakes above 1200 mg per day did not clearly get additional benefit from the intervention, suggesting that more is not necessarily better.</p>
<p>It’s clear that sufficient calcium is good for bone health, but at the heart of the recent debate over supplements are new [studies](https://theconversation.com/can-calcium-supplements-cause-heart-disease-7282](https://theconversation.com/can-calcium-supplements-cause-heart-disease-7282) linking calcium supplements with heart disease.</p>
<p>It’s a body of research that Professor Christopher Nordin, who has been working in the area of calcium metabolism and osteoporosis for more than 50 years, strongly refutes.</p>
<p>He says the evidence of benefit from calcium and vitamin D supplements is very well established, particularly for post-menopausal women, and points out that the Women’s Health Initiative study of post-menopausal women found no association between calcium supplements and heart attacks.</p>
<p>“The absorption of calcium goes down at the menopause and the urinary calcium goes up, so the requirement for calcium goes up,” Professor Nordin said.</p>
<h2>Commercially conflicted?</h2>
<p>Last month a group of doctors called for more scrutiny to be placed on the marketers of supplements, after the journal <a href="http://advances.nutrition.org/">Advances in Nutrition</a> published an article that was funded by a supplements trade association.</p>
<p>In a <a href="http://www.bmj.com/content/341/bmj.c4997">letter</a> to the editor published in the BMJ, Dr Ian Reid and colleagues from the <a href="http://www.auckland.ac.nz/uoa/">University of Auckland</a> said two of the six authors of the paper published by Advances in Nutrition are employees of the <a href="http://www.crnusa.org/">Council for Responsible Nutrition</a>, a trade association representing dietary supplement manufacturers.</p>
<p>The <a href="http://advances.nutrition.org/content/4/2/151.full?sid=2388b9d5-30ca-48e4-b444-65e0d4f1ca0e">paper</a> in question, by Dr R.P. Heaney of <a href="http://medschool.creighton.edu/medicine/departments/departmentofmedicine/divisions/endocrinology/osteoporosisresearchcenter/index.php">Creighton University’s Osteoporosis Research Centre</a>, argued the evidence presented to date on the relationship between calcium supplement use and increased cardiovascular disease risk was not sufficient to warrant a change in the Institute of Medicine recommendations, which advocates the use of supplements to promote bone health in people who do not get the recommended intake of calcium through their diet.</p>
<p>Dr Reid said it was a concern that the literature was being influenced by groups, such as CRN.</p>
<p>While the support of the CRN for the study in question was disclosed in the Advances in Nutrition article, Dr Reid said it was part of larger and carefully coordinated press campaign to promote a view that was commercially advantageous to the CRN and its members.</p>
<p>“The thing that struck about it was the blatancy with which it was done, and that really contrasts dramatically with what happens in the pharmaceutical arena. Most academics go to great strains not to be seen to be captured by any lobby group,” Dr Reid said.</p>
<p>However, Professor Nordin said there was very little profit and negligible industrial contribution from calcium and vitamin D supplements.</p>
<p>He went further and argued Dr Reid had no right to criticise Dr Heaney because he had in the past received funding support from Fonterra, a New Zealand multinational owned by dairy farmers.</p>
<p>Dr Reid said he had not received any funding from the dairy industry in the last three years and none of his calcium studies had been funded by them.</p>
<p>A paper by Dr Reid published in the BMJ in 2010 disclosed that he had previously received research support from, and acted as a consultant for, Fonterra.</p>
<p>Professor Nordin said he once received a grant from Roche who manufacture a form of vitamin D called calcitriol, and 60 years ago he received a travel grant from Sandoz who used to market a calcium preparation.</p>
<h2>Journals and responsibility</h2>
<p>Dr Reid argues academic journals need to be very aware of potential conflicts of interest, and is concerned there may be a double standard when it comes to supplements.</p>
<p>“I’m not confident in the supplements space generally that the levels of scrutiny are what we would expect in other areas such as the pharmaceuticals area,” he said.</p>
<p>However, physician and health ethicist Paul Komesaroff said as long as the partisan nature of the argument was openly stated, there was nothing wrong with scientists arguing the case for the manufacturers of calcium supplementation.</p>
<p>“Whether Heaney is employed by the drug industry or not does not invalidate his argument,” Professor Komesaroff said.</p>
<p>“In a court of law we are comfortable to accept the role of an advocate for a particular point of view - with the provision that the allegiance of the advocate is openly stated - and I can see no reason why we should not be equally happy with such a system in science.”</p>
<p>Professor Komesaroff added that despite claims to the contrary, no scientific argument is free from interests of some kind or other.</p>
<p>“Scientists like to think of themselves as radically sceptical, but this is far from the case. Indeed, it is well recognised that scientists become very attached to their own points of view and tend to resist change, even in the face of strongly contrary evidence.”</p>
<p>However, Dr Reid said there were other ways for supplement manufacturers to reach the market.</p>
<p>“If something is dressed up as an objective review and published in an academic journal then that is a less acceptable way for supplement manufacturers to express their point of view,” Dr Reid said.</p>
<p>The publisher and editor of Advances in Nutrition did not respond to our request for comment.</p>
<h2>Natural is best</h2>
<p>The NHMRC <a href="http://www.nrv.gov.au/nutrients/calcium.htm">recommends</a> adults have a daily intake of calcium of 1,000 milligrams per day, and this rises for women aged over 50 to 1,300 milligrams per day to account for increased need at menopause. It recommends an upper limit of 2,500 milligrams per day, with the rationale that adding 1,000 mg of calcium to a typical western diet would only increase calcium in urine by about 60 mg.</p>
<p>Vitamin D, made in the body by the action of sunlight on the skin, is also critically important, because it helps the body to absorb calcium.</p>
<p>The guidelines are similar in the United States, however the <a href="http://www.ahrq.gov/professionals/clinicians-providers/guidelines-recommendations/uspstfix.html">US Preventative Services Task Force</a> says more evidence is required to “assess the balance of the benefits and harms of daily supplementation with greater than 400 International Units of vitamin D and greater than 1,000 mg of calcium for the primary prevention of fractures in non-institutionalised postmenopausal women”.</p>
<p>Based on the available evidence, the strongest argument is that people should try to get their daily intake of calcium and vitamin D by eating a diet rich in these nutrients. For postmenopausal women, the benefits of supplements appear to outweigh the risks. With more research, the case for and against supplements is expected to become
clearer.</p><img src="https://counter.theconversation.com/content/12711/count.gif" alt="The Conversation" width="1" height="1" />
A clash between supporters and detractors of calcium supplements for better bone health is leading to conflicting headlines, leaving the public unsure about whom to believe. Osteoporosis is estimated to…Reema Rattan, Global Commissioning EditorCharis Palmer, Deputy Editor/Chief of StaffLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/72822012-06-20T20:44:39Z2012-06-20T20:44:39ZCan calcium supplements cause heart disease?<figure><img src="https://images.theconversation.com/files/11385/original/4dm79x8k-1338861850.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There’s no evidence suggesting that a calcium-rich diet causes heart problems.</span> <span class="attribution"><span class="source">Rachel James</span></span></figcaption></figure><p>People taking calcium supplements to mitigate their risk of developing bone disease (osteoporosis) may be doing more harm to their health than good. That’s because a growing body of research shows the supplements confer little benefit and increase the risk of developing heart disease. </p>
<p>Calcium supplements have also traditionally been thought to reduce the risk of heart attacks because they produce small beneficial changes in both blood pressure and blood cholesterol levels. We set out to test this idea in a trial we had originally designed to check the effect of calcium supplements on fractures and bone density. </p>
<p>To our surprise, what we <a href="http://www.bmj.com/content/336/7638/262">discovered</a> was that heart attacks were actually more common in the (randomly selected) women who received calcium supplements than those who had randomly been given inactive tablets.</p>
<p>When we <a href="http://www.bmj.com/content/336/7638/262">published this study</a> in the <a href="http://www.bmj.com/">British Medical Journal</a> in 2008, it caused widespread surprise among doctors working in the area, as well as the general public. So to test whether this was the true effect of calcium supplements, we decided to do a <a href="https://theconversation.com/how-do-we-know-what-works-systematic-research-reviews-5979">meta-analysis</a> of studies about taking them.</p>
<p>First, we contacted all the researchers who had carried out large trials of calcium supplements in the past to see whether they’d kept records of the medical problems that occurred in the course of the trials. </p>
<p>Data were available from 93% of trial subjects (almost 12,000 people) and these confirmed our finding that women who received calcium tablets in the studies had a 20% to 30% <a href="http://aura.abdn.ac.uk/bitstream/2164/756/1/Bolland%202010.pdf">increase in heart attack risk</a>. </p>
<p>We subsequently added to this database the results from other trials in which the <a href="http://www.bmj.com/content/342/bmj.d2040">intervention was calcium and vitamin D</a>, rather than calcium alone. This showed the same effect – a 25% increase in the risk of heart attacks and a 15% increase in the risk of stroke. </p>
<p>These results were based on almost 29,000 people participating in research and so were much more reliable than the results we had published previously. </p>
<p>From these analyses, we were able to determine that the number of heart attacks and strokes apparently caused by calcium supplements was greater than the number of fractures that they appeared to prevent. Naturally, we concluded that the use of calcium tablets was likely to be doing more harm than good and should be discontinued.</p>
<p>It’s very important to note that none of our analyses included the effect of calcium-rich foods, and there’s really no evidence suggesting that a calcium-rich diet causes heart problems.</p>
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<img alt="" src="https://images.theconversation.com/files/11382/original/mgdzxkbc-1338861666.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/11382/original/mgdzxkbc-1338861666.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=844&fit=crop&dpr=1 600w, https://images.theconversation.com/files/11382/original/mgdzxkbc-1338861666.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=844&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/11382/original/mgdzxkbc-1338861666.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=844&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/11382/original/mgdzxkbc-1338861666.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1060&fit=crop&dpr=1 754w, https://images.theconversation.com/files/11382/original/mgdzxkbc-1338861666.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1060&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/11382/original/mgdzxkbc-1338861666.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1060&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><span class="source">Matt Reinbold</span></span>
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<p>The reason for the difference between tablet supplements and food remains uncertain, but it may be related to the increase in blood calcium level that’s seen for several hours following the large dose of calcium in tablet form. In contrast, calcium in food is absorbed more slowly and has very little impact on blood calcium levels. </p>
<p>Elevations of blood calcium levels have previously been shown to <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2265.2010.03792.x/full">increase the risk of heart disease</a>, possibly through producing calcium deposits in the walls of blood vessels and accelerated arterial disease.</p>
<p>A number of <a href="http://www.sciencedirect.com/science/article/pii/S0378512209000954">other researchers have now looked</a> into these questions. This month, <a href="http://heart.bmj.com/content/98/12/920.full.pdf">researchers from Germany reported</a> that individuals taking calcium supplements appear to almost double the risk of heart attacks compared with people not taking supplements. And again, those who have high dietary calcium intakes tend toward lower risk of heart disease. </p>
<p>The German study didn’t randomly assign participants into groups taking calcium or placebo tablets, but simply reported events in individuals who had made the decision to take supplements independently. This is a less reliable way of determining the effects of an intervention than a randomised trial. Nonetheless, this observational study provides supportive evidence for the results of our trial analyses.</p>
<p>Last year, <a href="http://www.sciencedirect.com/science/article/pii/S0378512211001526">researchers in Sydney studied</a> the effects of calcium supplements in a very elderly group of individuals living in hostels. One-third of the 600 people in the group died during follow up. Death rates increased by 47% in those randomised to calcium and death from heart disease was increased by 76%.</p>
<p>So the weight of evidence that calcium supplements are bad for the heart has steadily increased. What, then, should people do in the face of these findings? </p>
<p>Calcium supplements are mainly used to reduce the risk of fractures from osteoporosis (a bone disease that leads to increased likelihood of fracture). But there are other important measures that will also contribute to osteoporosis prevention, such as regular exercise, not smoking, maintaining a healthy body weight, regular sunlight exposure to maintain vitamin D levels, and removal of falls hazards in the home (such as loose rugs, power cords, and slippery floors). </p>
<p>A steady supply of calcium is important for bone health, but research clearly shows this should be derived from a balanced diet that includes several servings of dairy products, or other calcium sources, such as dark green vegetables or tofu. </p>
<p>Women in their 60s and men in their 70s should have their risk of osteoporotic fractures formally assessed. This usually involves bone density measurement. </p>
<p>People found to be at high risk of fractures should consider using one of the medicines proven to safely reduce fracture risk. This is likely to be more effective than relying on the weak anti-osteoporotic effects of calcium supplements, which come at an unacceptably high price – the increased risk of heart disease.</p><img src="https://counter.theconversation.com/content/7282/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Reid consults to Sanofi and receives funding from Health Research Council of New Zealand.</span></em></p>People taking calcium supplements to mitigate their risk of developing bone disease (osteoporosis) may be doing more harm to their health than good. That’s because a growing body of research shows the…Ian Reid, Deputy Dean & Professor of Medicine, University of Auckland, Waipapa Taumata RauLicensed as Creative Commons – attribution, no derivatives.