PEOPLE taking calcium supplements have about a 30 per cent higher risk of heart attack, research suggests.
A review of existing studies on about 12,000 people found an increased risk for those on supplements, which are often prescribed to older women for the prevention or treatment of osteoporosis.
People taking supplements equal to 500mg or more per day were analysed through 11 studies, which compared them with people not on supplements.
According to the Food Standards Agency, adults need 700mg of calcium a day, which should come from dietary sources, including milk, cheese and green, leafy vegetables.
A study from experts at the University of Auckland and the University of Aberdeen said diets high in calcium do not increase the risk of heart attacks.
It is the effect of supplements, which increase the levels of calcium circulating in the blood, which causes the increased risk.
Experts believe higher blood serum levels lead to hardening of the arteries, which can cause heart attacks.
The authors said: “Serum calcium levels have been positively associated with an increased incidence of (heart attack) in large observational studies.
“Ingestion of equivalent doses of calcium from dairy products has a much smaller effect than calcium supplements on serum calcium levels”.
Today’s study excluded patients who were taking both calcium and vitamin D supplements. Vitamin D is needed for the body to absorb calcium.
The authors said it was unclear whether the findings would apply to these patients.
Nevertheless, they called for a rethink on giving people calcium supplements for bone health.
“Given the modest benefits of calcium supplements on bone density and fracture prevention, a reassessment of the role of calcium supplements in the management of osteoporosis is warranted,” they said, writing online in the British Medical Journal (BMJ).
Calcium has a number of important functions, including helping build strong bones and teeth.
It regulates muscle contraction, including the heartbeat, and makes sure the blood clots normally.
Carrie Ruxton, an expert with the Health Supplements Information Service, which is funded by an association representing supplement manufacturers, said: “It is important to note that calcium is an essential mineral for the health of the bones and the nervous system.
“Ensuring adequate intake is vital. However, the latest data from the UK National Diet and Nutrition Survey showed that one in 10 young women have calcium intakes below the lower reference nutrient intake (LRNI), a level at which deficiency is likely.
“Calcium supplementation can help to ensure adequate intakes in people with poor intakes or higher requirements, for example during growth.”
Judy O’Sullivan, senior cardiac nurse at the British Heart Foundation, said: “We need to be cautious about the results of this analysis because none of the studies involved were designed to look specifically at the relationship between calcium supplements and the risk of heart attack.
“However, the research should not be completely ignored. Any new guidelines on the prevention of fractures in those most vulnerable to them should take this type of analysis into account.
“Anyone who has been advised by their doctor to take calcium supplements shouldn’t stop because of this research alone.”