The Swedish study found that in taking calcium supplements to combat the onset of osteoporosis, older women may put themselves at a higher risk of developing a cerebrovascular disease and subsequently increase the chances of developing dementia.
The study’s findings, detailed in Neurology, the medical journal of the American Academy of Neurology, question the role of calcium supplements.
However, the researchers were quick to point out that the small sample size and observational nature of the research made further confirmation of the findings the necessary next step.
Calcium supplementation is considered the first line of defence for older women at risk of the brittle bone condition osteoporosis.
Back in 2010, the European Food Safety Authority (EFSA) approved a health claim stating: "Calcium and vitamin D help to reduce the loss of bone mineral in post-menopausal women. Low bone mineral density is a risk factor for osteoporotic bone fractures."
Researchers estimate that yearly 2.7m fractures suffered by European men and women are due to osteoporosis.
In 2010, the direct costs of osteoporosis fractures in the five largest EU countries were evaluated at €29bn and at €38.7bn in 27 members at the time.
The team from the Sahlgrenska Academy at the University of Gothenburg used a longitudinal population-based study approach.
Here, 700 dementia-free women aged 70–92 years were selected. From 2001 to 2006, these women were subject to a selection of tests designed to assess memory and thinking skills.
A CT brain scan was performed in 447 participants at the start of the study and data was collected from those who took calcium supplements.
Out of the women, who participated in the five-year study, 98 individuals were taking calcium supplements and 54 women had already experienced a stroke.
Over the study’s duration, 54 more women suffered strokes, whilst 59 women developed dementia.
Those who had CT scans revealed that 71% of women had lesions on their brains’ white matter. This observation is considered a marker for the onset of cerebrovascular disease.
“Because calcium deficiency contributes to osteoporosis, daily calcium intake of 1000 to 1200 mg is recommended,” said co-lead study author Dr Silke Kern, from the Sahlgrenska Academy at the University of Gothenburg.
“Getting this recommended amount through diet alone can be difficult, so calcium supplements are widely used.”
Calcium: Friend to the elderly?
Kern added that it was important not to assume that calcium supplements cause dementia and the results could not be generalised to the overall population.
The study noted that calcium-derived food was utilised differently by the body when compared to calcium supplements and may be protective against vascular problems.
The study hypothesised that a calcium surplus might affect the neurons that are especially vulnerable to the excitatory and excitotoxic effects of high calcium levels caused by the supplementation.
Calcium plays a major role in the onset of cell death. In this process, calcium ion influx activates enzymes that are responsible for degrading important proteins and disrupting membrane function.
“Blocking calcium influx (via receptors) prevents both necrosis and apoptosis. This indicates the crucial role of calcium influx and intracellular calcium overload in the genesis of apoptosis and necrosis,” the study noted.
Published online ahead of print, doi.org/10.1212/WNL.0000000000003111
“Calcium supplementation and risk of dementia in women with cerebrovascular disease.”
Authors: Dr Jürgen Kern and Dr Silke Kern et al.