Discussions about the dietary supplements are often far too general to be truly useful, in my view. For a meaningful debate, we need to define what supplement we are talking about and make clear what condition it is used for. A recent paper meets these criteria well and is therefore worth a mention.

The review was aimed at addressing the controversy regarding the optimal intake, and the role of calcium supplements in the treatment and prevention of osteoporosis. The authors demonstrate that most studies on the subject show little evidence of a relationship between calcium intake and bone density, or the rate of bone loss. Re-analysis of data from the placebo group from the Auckland Calcium Study demonstrates no relationship between dietary calcium intake and rate of bone loss over 5 years in healthy older women with intakes varying from <400 to >1500 mg per day .

The authors argue that supplements are therefore not needed within this range of intakes to compensate for a demonstrable dietary deficiency, but might be acting as weak anti-resorptive agents via effects on parathyroid hormone and calcitonin. Consistent with this, supplements do acutely reduce bone resorption and produce small short-term effects on bone density, without evidence of a cumulative density benefit. As a result, anti-fracture efficacy remains unproven, with no evidence to support hip fracture prevention (other than in a cohort with severe vitamin D deficiency) and total fracture numbers are reduced by 0-10%, depending on which meta-analysis is considered. Five recent large studies have failed to demonstrate fracture prevention in their primary analyses.

These facts, the authors argue, must be balanced against the possible harm. The risks of regularly taking calcium supplements include an increase in gastrointestinal side effects (including a doubling of hospital admissions for these problems), a 17% increase in renal calculi and a 20-40% increase in risk of myocardial infarction. Each of these adverse events alone neutralizes any possible benefit in fracture prevention.

The authors draw the following detailed conclusions: “Concern regarding the safety of calcium supplements has led to recommendations that dietary calcium should be the primary source, and supplements reserved only for those who are unable to achieve an adequate dietary intake. The current recommendations for intakes of 1000–1200 mg day−1 are not firmly based on evidence. The longitudinal bone densitometry studies reviewed here, together with the new data included in this review relating to total body calcium, suggest that intakes in women consuming only half these quantities are satisfactory and thus, they do not require additional supplementation. The continuing preoccupation with calcium nutrition has its origin in a period when calcium balance was the only technique available to assess dietary or other therapeutic effects on bone health. We now have persuasive evidence from direct measurements of changes in bone density that calcium balance does not reflect bone balance. Bone balance is determined by the relative activities of bone formation and bone resorption, both of which are cellular processes. The mineralization of newly formed bone utilizes calcium as a substrate, but there is no suggestion that provision of excess substrate has any positive effect on either bone formation or subsequent mineralization.

Based on the evidence reviewed here, it seems sensible to maintain calcium intakes in the region of 500–1000 mg day−1 in older individuals at risk of osteoporosis, but there seems to be little need for calcium supplements except in individuals with major malabsorption problems or substantial abnormalities of calcium metabolism. Because of their formulation, costs and probable safety issues, calcium supplements should be regarded as pharmaceutical agents rather than as part of a standard diet. As such, they do not meet the standard cost–benefit criteria for pharmaceutical use and are not cost-effective. If an individual’s fracture risk is sufficient to require pharmaceutical intervention, then safer and more effective measures are available which have been subjected to rigorous clinical trials and careful cost–benefit analyses. Calcium supplements have very little role to play in the prevention or treatment of osteoporosis.”

Clear and useful words indeed! I wish there were more articles like this in the never-ending discussion about the complex subject of dietary supplements.

13 Responses to Calcium supplements for osteoporosis: more risks than benefits?

  • Calcium alone really will not make any differences, but do researchers also take into account consumption of fats and oils and how active persons are, especially regarding that part of activity that takes place in the open air?
    Though there is also family (genetics+traditions), thin woman born to thin, vegan mother afraid of getting fat is one thing and woman robust woman born in a family of omniwores that do not bother about couple (but only couple) extra kg, is another.

    • “vegan mother afraid of getting fat”….what a weird statement: veganism is an attempt to live as ethically as possible, causing minimum harm to others and the planet, generally speaking the last thing on our mind is fear of fat. Vegan calcium intake is largely dietary from many plant based sources and not a problem: see reliable vegan nutritionists like Jack Norris or Ginny Messina for fulll information.

      • Rita, your statement strongly implies that, being a non-vegan and a non-vegetarian, my way of life is far less ethical than that of vegans. For some strange reason, I find that implication somewhat offensive — just as I find it offensive when religious persons tell me that being an atheist means I’ll spend an eternity in Hell: see a reliable deity for more information!

      • Except that plants are pretty much alive too.
        I think that ethical approach is abstaining from drugs, alcohol, tobacco (one need to destroy nature to grow raw materials), no overeating, no diets that harm body, including diets deficient in essential amino acids, vitamins and minerals which is often (not always) cause with vegans.

      • Fat fish and unskimmed milk products (most of us here are lactose tolerant) make the task of maintaining bone mass so much easier, than legumes, dried fruits, nuts etc …., though legumes are very good for many other reasons, dried fruits make good replacement of sweets …

        • people on this blog do appreciate when comments are supported by evidence/citations/references

          • Indeed, references are important.

            One issue of the calcium supplement debacle is that BMD is a poor determinant of risk.

            Why do I say this? Because T2D folks tend to have higher BMD, yet are at greater risk of fracture.
            Association between bone mineral density and type 2 diabetes mellitus: a meta-analysis of observational studies. 2012)
            Diabetes mellitus and risk of hip fractures: a meta-analysis. (2015)
            Effect of type 2 diabetes-related non-enzymatic glycation on bone biomechanical properties. (2015)
            This last article offers some insights into the more important measure than BMD…biomechanical properties.

            So what makes for good bones? Nutrients and using them via exercise.
            The references to K and D working with calcium in the bone remodeling process have been well documented, but mostly underappreciated by conventional docs (and maybe alternative ones, too).
            This is because we have lost our food roots, which offered nutrients that are now missing or they are blocked from proper actions by some drugs and some aberrant oils.

            For example, vitamin K2 (a vastly underappreciated nutrient/hormone) is a blockbuster for bones and other health aspects. But we have stopped eating it because we have been advised to shun egg yolks (high in MK-4), animal fats (also high in MK-4), as well as organ meats (high in longer chain menaquinones…especially liver), and we lost the cultural foods of fermented foods (natto in Japan, sauerkraut pretty much all over, cheese from many countries, kefir, yogurt, and so on) as well as lost the foods where we ate animals with their guts (insects, mollusks) since guts have bacteria that make long chain K2 (and ours’ do, too, but it is for them and for their energy and not so much for us, but they do contribute a little to our vitamin K status). Thus, little K2 in the Western diet.

            AND we block the action of dietary vitamin K (can be K1 or K2 of all forms) when we take some drugs (statins, bisphosphonates [oh the irony], NSAIDs) so these drugs hinder bone health and other aspects of health like heart health, mood/brain functioning, insulin sensitivity, maybe metabolism, and K2 is a powerful anti-inflammatory and antioxidant.

            AND we block the action of vitamin K (namely, activating K-dependent proteins and synthesizing MK-4 in tissues throughout the body) when we consume hydrogenated high phylloquinone oils (soy and canola) which makes an aberrant form of vitamin K called dihydrophylloquinone. Dihydrophylloquinone inhibits MK-4 synthesis and does not activate K-dependent proteins well.
            Just PubMed all these claims and be amazed.

            * we stopped eating K2 via loss of cultural foods and bad dietary advice from “experts”
            * K1 does not offer the same benefits as K2, but sill wonderful foods
            * we impair vitamin K actions of making a form of K2 in tissues throughout the body and activating K-dependent proteins via drugs and foods high in trans fatty acids (it looks like the dihydrophylloquinone is more damaging than the trans fatty acids – we tend to ask the wrong questions).

            Current US dietary guidelines consider vitamin K to be vitamin K1. We assess adequacy by coagulation time. And we ignore vitamin K2. Thus, American guidelines are myopic.
            However, other countries are looking at K2 a lot. And they are onto something big.

            A few Americans have delved into this (gone over like a fart in church – God, we are stupid);
            Vitamin K, an example of triage theory: is micronutrient inadequacy linked to diseases of aging?

            The physiology of vitamin K nutriture and vitamin K-dependent protein function in atherosclerosis.


            Those calcium supplements? Dumb. Other supplements that I may have mentioned (K2, maybe D, and also missing but also missing in our food, Mg) also unnecessary if one eats the whole real foods. And this can be ALMOST vegan (if one ferments), but the evidence is that we need at least some animal sourced foods since we need B12 and other nutrients in these foods (ha! to the vegan above).
            Why the ‘French Paradox?’ Because they eat liver and cheese! High, high in long chain K2 as well as many nutrients that work with it to make good bones with good mechanical loading abilities. It has nothing to do with saturated fats (I know, hard to believe after decades of dogma), but nutrients.
            And folks, we need these fat soluble nutrients!!
            Shun fat, lose them.
            Change fat, mess them up.
            Eat old fashioned fat, eat them.

            So, dear Edzard Ernst, please look into vitamin K2. I am not endorsing supplements (except for folks who are sick), but for the foods we lost and the oils we incorrectly adopted due to bad science of Keys, Ornish, etc.

            This might be a supplement you could endorse. Japan uses MK-4 to treat osteoporosis. I think that they should consider MK-7, but I am also critical of using only this one form of long chain K2 because MK-9 is so high in fermented dairy and it has shown true benefits. ALL the long chain forms should be better investigated.

            With the newly found appreciation of the microbiome, we need to learn more about fermented foods, too. They are nature’s probiotics.

  • I agree that it is nice to see such a good bit of research. My only observation is that when the average unscienced person reads, “…dietary calcium should be the primary source, and supplements reserved only for those who are unable to achieve an adequate dietary intake.”, s(he) may think that it is very difficult to achieve adequate dietary intake. Worse, if the person is already interested in (or blindsided by) alt med, s(he) will be primed to scoff at such an idea as people are constantly told that “mainstream” health practitioners do not understand nutrition, are not interested in prevention, only want to push drugs, only certain “magic” foods will achieve the desired goal, etc.

    A discussion of ordinary dietary sources and quantities should accompany such research. Information for vegetarians and vegans should be included. Amounts given should be related to actual food–not measurements.

    • Man, if you see a straw man, make sure and knock it down. In fact, the CAM world has been on to the observation that calcium supplements are not helpful for fracture prevention for a long time. Of course, they have just gone on to looking at and selling OTHER supplements (e.g., vitamins K and D, soy isoflavones).
      This is not meant to be a defense of the supplement industry, but remember, it’s not the small DSHEA manufacturers making the big bucks off calcium, but the mass market products that you see at the grocery and pharmacy.
      I think it is the guidelines folks who have been late to make any significant reaction to the science. For example, the American Geriatrics Society and the National Osteoporosis Foundation both recommend calcium supplements for post-menopausal women without reservation. To me, this feels like another example of biological plausibility trumping evidence in clinical practice.

  • I should ammend the last bit about amounts of food. One cup of skimmed milk make sense, but I often see 2 oz cheese, as though everyone carries around a little kitchen scale. Few discussions go beyond dairy sources for calcium which makes veg and vegan tune out. Real medicine has to be responsive and thorough. Critiquing studies is not enough for the great unwashed.

  • ” If an individual’s fracture risk is sufficient to require pharmaceutical intervention, then safer and more effective measures are available which have been subjected to rigorous clinical trials and careful cost–benefit analyses.”
    Please elaborate on these effective measures.

  • Calcium supplements aren’t for everyone. For instance, if you have a health condition that causes excess calcium in your bloodstream (hypercalcemia), you should avoid calcium supplement Until more is known about these possible risks, it’s important to be careful to avoid excessive amounts of calcium. As with any health issue, it’s important to talk to your doctor to determine what’s right for you. for more

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