So far, it has been unclear whether or not calcium supplementation increases the risk of dementia, the study authors noted.

Their current analysis was based on data from a double-blind randomized controlled trial, where older women received 1,200 milligrams (mg) of calcium bicarbonate supplementation daily, or a daily placebo for 5 years. This original research had been to determine if calcium supplementation helped prevent fractures.

Participants were mobile women who were at least 70 years old and did not have dementia at baseline. The participants were also part of follow-up studies, so researchers of the current analysis were able to look at 14.5 years’ follow-up.

Researchers looked for incidence of all-cause dementia events. These events were hospitalizations related to dementia, deaths related to dementia, or both.

Researchers also had extensive additional data on participants, such as body mass index (BMI), smoking status, alcohol intake, and physical activity. For the current study, they completed an unadjusted analysis and then corrected for an increasing number of covariates in models. Some women were excluded from some analyses because they had missing covariate data.

Finally, the authors conducted additional analyses that considered components like prevalent atherosclerotic vascular disease and participants’ overall calcium intake. They also looked at abbreviated mental test scores to examine participants’ cognitive function in the placebo versus the intervention group after the 5 years of calcium intake.

Throughout follow-up, about 18% of the participants had a dementia event.

Overall, dementia outcomes were about the same for participants who took the calcium supplement and those who took the placebo in the unadjusted analyses.

This was true for overall dementia events, hospitalizations related to dementia, and deaths related to dementia. The results were similar in the adjusted models that considered all three of these outcomes.

For special consideration scenarios, like atherosclerotic vascular disease, the results for dementia events overall were similar between the placebo and calcium groups. Abbreviated mental test scores were comparable between the groups as well.

Study authors Marc Sim, PhD, Edith Cowan University research fellow, and Negar Ghasemifard, a doctoral student at the same institution, explained the main findings of their research to Medical News Today.

“We did not see any sign that taking calcium supplements, at a level commonly used to support bone health, increased the risk of dementia,” Sim and Ghasemifard told us. “

“Specifically, no difference in the risk for dementia in the placebo and calcium-supplemented groups was recorded. Results remained consistent even after accounting for women with more than 80% adherence to the intervention, dietary calcium intake, and genetic risk,” they norted.

“In short, for community-dwelling older women, 5 years of calcium supplements did not increase the long-term risk for dementia.”
— Marc Sim, PhD, and Negar Ghasemifard

There are a few limitations to the study. The researchers’ definition of dementia events was limited, as they only involved hospitalization, death related to dementia, or both.

Participants self-reported some information, which could lead to inaccurate data. Missed data and covariates that researchers did not account for could impact results. Further, the researchers did not have data on participants’ education levels, which can affect dementia risk.

In the original research, there was imperfect adherence to taking calcium supplements. The research sample was older white women citizens in Western Australia with higher socioeconomic status, so it is unclear if the findings can be generalized to other groups.

The researchers also noted that people who participate in clinical studies are usually healthier and have better education than the general population. This fact may limit the generalizability of the findings and introduce selection bias.

Then, the authors only had data on the use of calcium supplements for the 5 years of the trial intervention. They also emphasized that the original study was also not made to look at dementia or cognition as main or secondary outcomes. Furthermore, there was a limited assessment of cognitive function available among participants, and the abbreviated mental test scores can only reveal so much.

The researchers also only focused on Alzheimer’s disease, vascular dementia, and unspecified dementias when it came to dementia diagnoses, and they considered all of these dementias together.

They noted that since they focused on all-cause dementia, it remains unclear if there would be differing risks based on dementia subtypes.

Most participants were older than 80 when dementia events occurred, so researchers also advised caution in “interpreting the findings with respect to dementia events occurring before 80 years of age.”

Calcium intake was substantial enough in both groups, so it is unclear if the results would apply to women who do not have a lot of calcium in their diets.

It is also possible that there were more dementia cases than what was reported due to researchers using linked hospital discharge administrative data, which is less sensitive than doing chart reviews.

Analyses considering atherosclerotic vascular disease and stroke were also limited and thus may require additional follow-up and research.

Speaking about further research on this topic, Sim and Ghasemifard told us that:

“Studies that are specifically designed to track brain health over time would be a welcome addition. Our analysis repurposed data from a randomized control trial considering calcium and fractures, so brain health wasn’t the main focus. Future research could also include more diverse groups (e.g., men, younger women) and cognitive tests, as well as brain imaging.”

While more research is needed, the data so far does appear to support the safety of calcium supplementation.