Side effects of excessive calcium supplementation
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Cardiovascular Side Effects of Excessive Calcium Supplementation
Excessive calcium supplementation has been linked to an increased risk of cardiovascular diseases, including heart attack, stroke, arterial calcification, and heart rhythm disorders. Several studies and meta-analyses have found that high calcium intake, especially from supplements rather than dietary sources, is associated with a 27–31% increased risk of myocardial infarction and a 12–20% increased risk of stroke in older adults. The risk appears to be higher in those with already adequate dietary calcium intake and in individuals with reduced kidney function, as their bodies are less able to eliminate excess calcium, leading to soft-tissue and vascular calcification. The mechanisms proposed include changes in vascular cell function, increased blood coagulation, and direct effects on blood pressure and heart muscle relaxation. Notably, dietary calcium does not show the same adverse cardiovascular effects as supplements, suggesting that food sources are safer for meeting calcium needs 123467.
Kidney Stones and Renal Complications from High Calcium Intake
A well-established side effect of excessive calcium supplementation is an increased risk of kidney stones (nephrolithiasis). Studies have shown a 17% higher risk of developing kidney stones among those taking calcium supplements compared to those who do not. This risk is particularly relevant for individuals with a history of kidney stones or those at higher risk due to other medical conditions 110.
Gastrointestinal Side Effects of Calcium Supplements
Gastrointestinal (GI) symptoms are common among individuals taking high doses of calcium supplements. These side effects include constipation, abdominal cramping, bloating, and, less frequently, severe diarrhea or abdominal pain. The incidence of GI adverse events is significantly higher in those taking calcium supplements compared to placebo, with some studies reporting rates as high as 14% in the supplement group versus 10% in the placebo group 1510.
Uncertainty and Controversy in Cardiovascular Risk
While many studies report an increased risk of cardiovascular events with calcium supplementation, some large trials and meta-analyses have not found a significant association, especially when calcium is taken with vitamin D. The evidence is mixed, and some experts argue that the increased risk may be limited to certain populations or may be influenced by study design and participant characteristics. However, the overall trend in the literature suggests caution, particularly for those with adequate dietary calcium intake or pre-existing cardiovascular risk factors 7810.
Conclusion
Excessive calcium supplementation is associated with several potential side effects, most notably an increased risk of cardiovascular events, kidney stones, and gastrointestinal symptoms. The risks appear to be higher with supplements than with dietary calcium. Individuals considering calcium supplements should do so under medical guidance, weighing the benefits for bone health against the potential for harm, especially if they already have sufficient dietary calcium or are at risk for heart or kidney problems 123456710.
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