Swedish investigators sent questionnaires to 61,433 Swedish women who were due to undergo routine mammography. The questionnaires asked about food consumption, allowing them to estimate nutrient intake using standard portion sizes. A second questionnaire was also sent that included information on dietary supplements. The reference for comparison was 800mg of calcium, corresponding to the recommended daily intake for Swedish women over 50 years.
High total (i.e. both dietary and supplement) calcium intake was associated with a significantly increased risk of death from all causes. Women who had a total intake of over 1400mg per day were 40% more likely to die, compared with those with a total intake of 600mg to 999mg per day, and were 49% more likely to die from cardiovascular disease, compared with women taking a total of 600mg to 999mg per day. The same group were over two times more likely to die from ischaemic heart disease, compared to women with a total intake of 600mg to 999mg per day.
What does it mean for GPs?
The authors concluded that the data suggests that ‘for the prevention of fractures in older people and simultaneous avoidance of possible serious adverse events related to high calcium intake, emphasis should be placed on people with a low intake of calcium.’ The findings conflict with another recently published analysis that showed calcium supplementation increased the risk of death from cardiovascular disease in men, but not in women.