For strong bones, avoid excess Calcium!
Written by Robyn Chuter
Created Monday, 25 June 2012
Yes, you read that right! The dairy, nutritional supplement and pharmaceutical industries, not to mention dietitians and doctors, have been urging you for years to increase your calcium intake for the sake of your bones. Yet there is not a shred of evidence that upping calcium intake above a relatively low threshold, improves bone health or reduces the risk of bone fractures. (Read my article on osteoporosis for more information and scientific references.) A study published in 2011 in the prestigious British Medical Journal hammers another nail into the coffin of the eat-more-calcium-for-stronger-bones myth, with the finding that women with the highest intake of calcium had a 19% higher risk of experiencing a hip fracture than those whose calcium intake was modest but adequate.
This study's strengths included
- the large number of study subjects (over 60 000 Swedish women);
- the duration of follow-up (19 years);
- the fact that it was prospective (i.e. the participants were recruited before any of them had suffered a fracture) and calcium intake was repeatedly measured over the follow-up period, eliminating the problem of 'recall bias' -the tendency of people who have already suffered a disease, to overestimate their past exposure to risk factors for it - that plagues retrospective studies;
- and the statistical adjustment for various other factors that affect bone health and fracture risk, such as smoking, physical activity level, and whether the women had had children (which decreases fracture risk).
The researchers analysed the participants' diet records, and divided them into 5 groups, from lowest to highest calcium intake. They found that women with the lowest calcium intake from foods and supplements (less than 750 mg per day) had an 18% higher risk of suffering any type of fracture, and a 29% greater risk of hip fracture, than women who consumed 882-996 mg of calcium per day (an amount easily achieved on an entirely plant-based diet, high in green leafy vegetables, legumes, nuts and seeds).
However, women with the highest calcium intake (more than 1137 mg per day) had a 19% higher risk of suffering a hip fracture than those in the 882-996 mg/day group. Given that the Australian government now recommends a daily intake of 1300 mg of calcium for individuals over 50, and many older women are taking more than 1000 mg per day of calcium from supplements, above and beyond what they obtain through their diet, the findings from this carefully-conducted study must give serious pause for thought.
The researchers discussed several possible explanations of their findings, which fly in the face of the advice given to women in Austraila and other industrialised countries. The first is that whereas the arm and leg bones usually enlarge as we age, to compensate for the normal age-related decline in bone mineral density, high calcium intake reduces this enlargement and thus puts our bones at higher risk of fracture. Secondly, high calcium intake slows down bone turnover and reduces the number of active bone remodelling sites, delaying the repair of bone damage caused by everyday physical stresses. This delayed repair increase the risk of fractures even if bone mineral density is relatively high.
As another researcher has pointed out, when calcium enters bones, the osteoblasts (bone-building cells) respond by laying down a protein matrix onto which the calcium precipitates, and in the process, 50-70% of these osteoblasts die. Higher calcium levels within bone lead to greater osteoblast activity and more osteoblasts dying. Over time, this leads to a lower age-related osteoblast replicative capacity (ARORC), which eventually results in insufficient osteoblasts to repair the microfractures which occur in bone due to normal daily activity.
It's worth pointing out here, that if you're consuming less than 750 mg of calcium per day, then you are definitely not consuming enough green leafy vegetables, seeds, nuts and other calcium-rich foods, and hence you're also missing out on other bone-building nutrients such as plant protein, vitamin K, magnesium, boron and potassium. In other words, the nutritional quality of your diet is exceedingly poor. Increasing your intake of nutrient-dense plant foods will bump your calcium intake up over the threshold level that the Swedish researchers found. But if you're already having this much calcium thanks to an overall healthy diet, there's absolutely no advantage to you further increasing your calcium intake, and in fact there's a risk of significant harm.
The researchers also found that low vitamin D intake increased the risk of fracture in the low-calcium diet group. As I have previously written, testing your vitamin D level, and increasing it if necessary through judicious sun exposure and supplemention, is an absolute must if you wish to enjoy good health into old age.
The bottom line: if you want strong bones and protection against fracture, improve the nutritional quality of the diet and bury those calcium pills in the garden, under your parsley patch!
This article was previously published on the Empower Total Health website
Robyn Chuter is a university-qualified naturopath, with a Bachelor of Health Science (and the Dean's Medal for Outstanding Academic Achievement) from the University of New England, and a Diploma of Naturopathy from the Australasian College of Natural Therapies. Robyn runs the website Empower Total Health; and she has a naturopathic practice in Sydney, Australia where she specialises in chronic, medically 'incurable' health problems such as IBS, CFS, migraine, high blood pressure and type 2 diabetes.
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