Calcium Warning Debunked: Supplements Not Linked To Dementia In Older Women

PERTH, Australia — Millions of older women take calcium pills to keep their bones strong, but many have worried the supplements might harm their memory. A 14-year study following nearly 1,500 Australian women offers good news: taking calcium every day doesn’t increase the risk of developing dementia.

Scientists followed women in their 70s and 80s who took 1,200 milligrams of calcium daily for five years, then tracked their health for nearly a decade more. Out of 1,460 women in the study, 269 developed dementia over time. The numbers were split almost evenly: 128 women taking calcium and 141 women taking fake pills. The rates were essentially the same in both groups.

“Compared to placebo, calcium supplements did not increase risk of dementia-related events,” the researchers wrote in The Lancet Regional Health – Western Pacific. The results held up even when accounting for genetics, heart problems, lifestyle choices, and whether women actually remembered to take their pills.

So why were people worried in the first place? A 2016 study from Sweden suggested women on calcium supplements faced three to seven times higher dementia risk, especially those who’d had strokes. Another small study found calcium users had more concerning spots on brain scans. These reports made some doctors and patients wonder if protecting bones came at the expense of brain health.

How This Study Differs from Previous Research

This Australian research is different because it comes from a carefully designed experiment, not just observational data. The Swedish study looked at women who were already taking calcium and compared them to women who weren’t. The problem? Women taking calcium were probably doing so because they already had weaker bones or other health issues.

In this study, researchers flipped a coin (essentially) to decide who got calcium and who got sugar pills. Half of the 1,460 women got real calcium supplements (600 milligrams twice a day), while the other half got identical-looking fake pills. Nobody knew who was getting what during the five-year treatment period from 1998 to 2003.

After the experiment ended, researchers kept tabs on the women through medical records until 2013. They looked for dementia diagnoses in hospital records and on death certificates. Over the full 14.5 years, 243 women were hospitalized with dementia and 114 died with dementia listed as a contributing cause.

The researchers checked results two different ways. First, they counted everyone who started the study, even women who stopped taking their pills. Then they looked only at women who took at least 80% of their assigned pills (830 women stuck with the program). Both approaches showed the same thing: calcium didn’t raise dementia risk.

Some factors did matter for dementia risk. Women who developed dementia were more likely to carry a gene variant called APOE ε4, which increases Alzheimer’s risk. About 35% of women who got dementia had this gene compared to just 21% who didn’t. They were also more likely to have been smokers (45% versus 35%) and were a bit older when the study started. But taking calcium? That made no difference, even after accounting for age, weight, genetics, blood pressure, medications, diabetes, heart disease, diet, alcohol use, smoking, exercise, and income level.

Why the Swedish Study May Have Been Wrong

According to the authors of this new study, the Swedish research had a major flaw. It relied on pharmacy records to figure out who was taking calcium. Women identified as calcium users probably needed the supplements because they already had osteoporosis or fragile bones. These women broke bones at nearly twice the rate of non-users (41% versus 21%), showing they were sicker from the start.

Here’s an important point: breaking a bone is itself a risk factor for dementia. Fractures can lead to hospital stays, long periods of inactivity, and complications that affect the brain. So was it the calcium causing dementia, or the underlying bone weakness and fractures? With such small numbers in the Swedish study (only 98 calcium users, and just six who developed dementia), it’s nearly impossible to tell.

In this Australian study, fracture rates were the same in both groups (27% for calcium, 29% for fake pills). Random assignment worked: it created two groups that were truly comparable. The study also had more statistical power, with 269 dementia cases compared to just 59 in the Swedish study.

Another big advantage: the researchers knew exactly how much calcium each woman took. They handed out the pills themselves and counted what came back at yearly checkups. On average, women in both groups took about 57% of their assigned pills over five years. When looking only at women who took at least 80% of their pills, results stayed the same. Interestingly, women who took their pills more consistently had slightly lower dementia risk overall, but this was true for both the calcium group and the fake-pill group. Taking your pills as directed is generally a sign of better health habits.

Testing Whether Heart Disease Changes the Picture

The research team wondered if calcium might harm women who already had heart or blood vessel problems, since earlier studies hinted at this. They looked at 178 women with a history of clogged arteries or heart disease. Even in this higher-risk group, calcium showed no link to dementia.

Researchers also did ultrasounds in year three to measure artery wall thickness and look for plaque buildup, both early warning signs of heart disease. Adding these measurements didn’t change anything. Calcium doesn’t seem to cause dementia through damaging blood vessels.

Another question: maybe it’s not the supplements alone, but total calcium intake that matters? Women in the study were eating about 960 milligrams of calcium daily from food (about 70% of what’s recommended for their age). The research team calculated each woman’s total calcium by adding up what she ate plus how many pills she actually took. Women assigned to calcium supplements ended up consuming around 2,160 milligrams total per day.

When researchers split participants into higher and lower calcium intake groups (using 1,610 milligrams as the cutoff), dementia rates looked similar in both. More calcium, whether from food or pills, didn’t increase risk.

At the end of five years, researchers gave everyone a brief memory test. Scores were identical in both groups, another sign that calcium wasn’t affecting brain function.

What This Study Couldn’t Tell Us

The researchers are upfront about what their study can’t answer. All participants were White Australian women, so we don’t know if results would be the same for men, people of other ethnicities, or younger adults. The women who volunteered were probably healthier and better educated than average, though their rate of health problems matched what’s typical for this age group.

Researchers only tracked calcium pill use during the five-year experiment. They don’t know if women kept taking supplements after 2003. The study relied on hospital and death records to identify dementia cases. This method misses some cases but is very accurate for the ones it catches. About 18% of women in this study developed dementia over 14.5 years, which matches rates in similar populations.

The original experiment was designed to study broken bones, not memory problems. Researchers didn’t give detailed cognitive tests or track different types of dementia (like Alzheimer’s versus dementia from strokes). Most dementia cases (about 91%) happened after age 80, so we should be cautious applying these findings to younger women.

Here’s the bottom line: roughly one in five women over 70 has osteoporosis, and calcium supplements remain a key treatment. For older women trying to decide whether the bone benefits are worth potential brain risks, this study offers reassurance. Taking calcium at commonly prescribed doses for five years didn’t increase the risk of developing dementia over the next decade and a half.

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