{"entity":{"id":"calcium-supplements","kind":"technology","name":"Calcium supplements during and after cancer treatment","aka":["Calcium carbonate","Calcium citrate"],"tldr":"Calcium, often with vitamin D, is widely taken to protect bones during hormone treatment for breast or prostate cancer, but the evidence that supplements alone prevent bone loss in these settings is insufficient. High-dose supplements carry risks, including kidney stones and possibly stroke, and calcium can raise blood calcium in people taking tamoxifen.","summary":"Memorial Sloan Kettering's About Herbs entry finds the evidence insufficient to assess calcium plus vitamin D supplementation for people on androgen deprivation therapy, aromatase inhibitors or with chemotherapy-induced menopause, and advises discussing it with the oncology team because calcium interacts with several medicines. Supplementation did not prevent bone density loss in breast cancer patients in the studies MSK cites. Dietary and supplemental calcium are associated with lower colorectal cancer risk, while high calcium intake is associated with prostate cancer; results for other cancers are conflicting. MSK lists the risks of supplements: kidney stones with calcium plus vitamin D, possible increased cardiovascular risk especially in chronic kidney disease, ischaemic stroke with more than 1 g a day, and milk-alkali syndrome, including a life-threatening case in a cancer survivor taking calcium antacids. Interactions include possible hypercalcaemia with tamoxifen, reduced absorption of quinolone and tetracycline antibiotics and of levothyroxine, and competition with iron, zinc and magnesium. Calcium from food is preferred where possible; bone protection on aromatase inhibitors or androgen deprivation is managed with bone density scans and, where needed, prescribed drugs such as bisphosphonates or denosumab.","status":"phase-2","asOf":"2026-11-04","links":[{"label":"MSK About Herbs: Calcium (page last updated 24 September 2026)","url":"https://www.mskcc.org/cancer-care/integrative-medicine/herbs/calcium"}],"tags":["complementary","supportive-care","evidence:insufficient"],"related":["magnesium-supplements","coral-calcium"],"cancers":[],"sections":["supportive-care","nutrition-lifestyle","hormonal"],"technologies":["integrative-oncology","dietary-supplements-treatment-interactions","endocrine-therapy"],"targets":[],"drugs":["tamoxifen","letrozole","anastrozole","exemestane"],"companies":[],"institutions":[],"pathways":[],"terms":["aromatase-inhibitor"],"trials":[],"people":[],"bottlenecks":["b-toxicity-qol","b-survivorship"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"principle":"Calcium is the main mineral of bone; whether extra calcium changes bone loss driven by oestrogen or testosterone deprivation is the uncertain part.","strengths":["Dietary calcium associated with lower colorectal cancer risk","Part of guideline bone care when intake is low"],"limitations":["Insufficient evidence that supplements prevent treatment-related bone loss","Kidney stones, possible cardiovascular and stroke risk at high doses","Hypercalcaemia risk with tamoxifen; antibiotic and thyroid interactions"]},"route":"/technologies/calcium-supplements/","neighbours":{"technology":[{"id":"coral-calcium","kind":"technology","name":"Coral calcium","route":"/technologies/coral-calcium/"},{"id":"dietary-supplements-treatment-interactions","kind":"technology","name":"Dietary supplements during cancer treatment: interactions and harms","route":"/technologies/dietary-supplements-treatment-interactions/"},{"id":"endocrine-therapy","kind":"technology","name":"Endocrine therapy (SERMs, AIs, SERDs)","route":"/technologies/endocrine-therapy/"},{"id":"integrative-oncology","kind":"technology","name":"Evidence-based integrative oncology","route":"/technologies/integrative-oncology/"},{"id":"magnesium-supplements","kind":"technology","name":"Magnesium supplements","route":"/technologies/magnesium-supplements/"},{"id":"zinc-supplements","kind":"technology","name":"Zinc supplements for taste changes and mucositis","route":"/technologies/zinc-supplements/"}],"section":[{"id":"nutrition-lifestyle","kind":"section","name":"Diet, Exercise & Lifestyle","route":"/fronts/nutrition-lifestyle/"},{"id":"hormonal","kind":"section","name":"Hormonal Therapy","route":"/fronts/hormonal/"},{"id":"supportive-care","kind":"section","name":"Supportive Care & Survivorship","route":"/fronts/supportive-care/"}],"drug":[{"id":"anastrozole","kind":"drug","name":"Anastrozole","route":"/drugs/anastrozole/"},{"id":"exemestane","kind":"drug","name":"Exemestane","route":"/drugs/exemestane/"},{"id":"letrozole","kind":"drug","name":"Letrozole (and other aromatase inhibitors)","route":"/drugs/letrozole/"},{"id":"tamoxifen","kind":"drug","name":"Tamoxifen","route":"/drugs/tamoxifen/"}],"term":[{"id":"aromatase-inhibitor","kind":"term","name":"Aromatase inhibitor","route":"/terms/aromatase-inhibitor/"}],"bottleneck":[{"id":"b-survivorship","kind":"bottleneck","name":"Survivorship and late effects are neglected","route":"/bottlenecks/b-survivorship/"},{"id":"b-toxicity-qol","kind":"bottleneck","name":"Toxicity and quality of life are undervalued","route":"/bottlenecks/b-toxicity-qol/"}]}}