There isn't a month goes by without publication of new research that demonstrates a link between some dietary factor or supplement and increased risk of cardiovascular disease and mortality. The information in the end I suspect is so confusing it is little wonder that for the most part it is ignored. It is the problem of information overload.
Nonetheless there are good reason for taking this new study seriously, not least because experts recommend a high calcium intake for women in middle age and increasingly people are turning to calcium supplements.
As a result more than 60% of middle-aged and older women in the USA now take supplements and it is estimated that up to 5 million people in the UK take them. What this study demonstrates is that more care should be taken in assessing the need for dietary calcium supplements.
Normally the level of calcium in the blood is tightly regulated and does not fluctuate with changes in dietary intake. What the authors of the study in today's bmj suggest is that this essential regulation may breakdown due to calcium overload if calcium supplements are taken over long periods. The mechanisms regulating calcium in the body become disturbed.
A healthy balanced diet should provide all the calcium we need. But there are times when this might have to be supplemented. To maintain constant concentrations of calcium in blood, muscle, and body fluids the body uses bone tissue as a reservoir. Some 99% of the body's calcium is stored in our bones. But this balance changes with age.
As we get older the balance of bone loss and reformation deteriorates. As a result the bone becomes less dense and more fragile. This is particularly so in post menopausal women with the risk of osteoporosis. Women with osteoporosis have lower total-body calcium levels
The researchers conclude that high calcium is associated with “higher all-cause and cardiovascular mortality rates”. The take home message is that to prevent fractures in the elderly emphasis should be placed on individuals with a low intake of calcium rather than increasing the intake of those already consuming satisfactory amounts in their diet.