Recent research suggests that calcium supplements may, in fact, cause some health problems. However, the evidence is mixed.

They may increase risk of heart disease

Perhaps the most controversial suggestion about calcium supplements is that they may increase the risk of some types of heart disease, including heart attack and stroke.

A 2021 analysis of 13 clinical trials found that calcium supplements increased cardiovascular disease (CVD) risk by 15% in healthy postmenopausal women (20).

A 2020 analysis of 42 studies found that calcium from dietary sources did not raise CVD risk but supplemental calcium did (21).

A 2022 study in South Korea found similar risks of CVD when a large group of subjects took calcium supplements (22).

More conclusive research is needed to determine the effect of calcium supplements on heart health. Some experts have suggested that taking calcium with vitamin D may neutralize the possible risks, but this needs to be studied more (23).

High levels may be linked to prostate cancer

High levels of calcium may be linked to prostate cancer, although the research on this link is also conflicting.

In several studies, most of which were observational, researchers found that high intakes of calcium may be linked to an increased risk of prostate cancer (24, 25).

However, an older randomized controlled study that gave 672 men either a calcium supplement or placebo every day for 4 years showed that participants did not have an increased risk of prostate cancer.

In fact, participants who took the supplement had fewer cases of prostate cancer (26).

Other research has suggested that dairy products may be the culprit. A review of 32 articles reported that consuming dairy products — but not calcium supplements — was linked to an increased risk of prostate cancer (27).

Risk of kidney stones may increase

There is some evidence that calcium supplements increase the risk of kidney stones.

One study looking at hip health gave more than 36,000 postmenopausal women either a daily supplement containing 1,000 mg of calcium and 400 IU of vitamin D or a placebo pill.

The results showed that those who took the supplement had an increased risk of kidney stones (28).

Furthermore, while supplement users in the study experienced an overall increase in hip bone density, they didn’t have a lower risk of hip fractures.

The risk of kidney stones appears to be linked more to supplements than to calcium derived from the diet (29).

Consuming more than 2,000 mg of calcium per day from your diet or supplements is also linked to an increased risk of kidney stones, according to the Institute of Medicine (30).

Other sources say that the risk of kidney stones increases when calcium intake exceeds 1,200-1,500 mg per day (31).

High levels of calcium in your blood

Having too much calcium in your blood leads to a condition called hypercalcemia, which is characterized by many negative symptoms, including stomach pain, nausea, irritability, and depression.

It can be caused by several things, including:

• experiencing dehydration
• having a thyroid condition
• taking high levels of calcium supplements

Excessive vitamin D supplements may also lead to hypercalcemia by encouraging your body to absorb more calcium from your diet.

Summary

Calcium supplements may increase the risk of heart disease and prostate cancer, although the link is unclear. Extremely high levels of calcium from any source may have negative health effects.