Bones boost helps heart

Auckland researchers have found a link between calcium supplements and improved cholesterol balance, reports MARTIN JOHNSTON.

Swallowing a calcium tablet daily improves people's cholesterol levels and could cut the risk of heart disease and stroke.

Cardiovascular disease - mainly heart disease and stroke - is New Zealand's leading killer, accounting for 40 per cent of deaths.

Researchers at the Auckland Medical School looking at the effects of calcium supplements on bone fractures found that it altered cholesterol balances beneficially.

In the study, 223 post-menopausal women were randomly assigned into two groups and given either 1g daily calcium supplements or dummy pills.

After a year, the researchers found that in the calcium group, the levels of so-called "good" cholesterol had risen by 7 per cent. "Bad" cholesterol had declined by 6 per cent.

In the dummy-pills group there was virtually no change.

Bad cholesterol (LDL or low-density lipoproteins) can be deposited on the walls of arteries, causing the narrowing that can lead to heart disease and stroke.

Good cholesterol (HDL or high-density lipoproteins) is protective because it removes LDL from the blood stream.

The lead researcher in the Auckland study, Professor Ian Reid, said diseased arteries were the commonest cause of death in post-menopausal women.

He speculated that the degree of change in cholesterol balance found in the calcium group could cut these women's risks of stroke or heart disease by 20 per cent to 30 per cent.

"The message is that in terms of what actually finally kills people, calcium might be having greater beneficial effects on the heart than it's having on the bones."

Calcium supplements are recommended to slow the onset of the bone-weakening condition osteoporosis.

Post-menopausal women, who were especially vulnerable to the loss of bone mass, were generally recommended to have a daily calcium intake of 1200mg to 1500mg, the professor said.

In New Zealand this group's normal dietary intake, mainly from green vegetables and dairy foods, was around 700mg, so they needed to take supplements, which came in 500mg and 1g tablets.

"What most doctors do is, in people at risk of osteoporosis, recommend taking [a supplement] of 1g a day."

For men, the recommendation was to have a dietary intake of 800mg to 1000mg a day, he said. Trials were yet to establish whether supplements helped to slow their bone loss.

Professor Reid said it was unclear how calcium supplements affected cholesterol, but it was likely that it bound to fatty acids and bile acids in the gut, interfering with fat absorption.

The study, published in the American Journal of Medicine, says the findings justify encouraging more use of calcium supplements for post-menopausal women, as well as trying it with men, and testing directly the effects on the risks of heart disease and stroke.

The National Heart Foundation said the Auckland study added to the small body of evidence on calcium's beneficial effects on cholesterol.

But the evidence was not yet strong enough for the foundation to recommend taking calcium supplements to manage cholesterol levels, said its national dietician, David Roberts.

Professor Reid said no adverse effects from calcium were found in the latest study, although people with a history of kidney stones should avoid calcium supplements except on the advice of a doctor.

nzherald.co.nz/health