Supplement
Calcium is a mineral that builds and maintains your bones and teeth and helps nerves and muscles work. Its main use in the research here is bone health, though the clearest trial findings came from pregnancy, where calcium was linked to a lower risk of preeclampsia and the evidence is strong. Those results came from a handful of trials and reviews, and the effect size was moderate. The benefit was seen mostly in women with low dietary calcium.
Sources: PMID 9396883; PMID 39608269
- Updated
- How we grade
- 22 studies cited
- Best evidence
- Grade A
- Conditions studied
- 17
- Outcomes
- 32
- Graded outcomes
- 1347
Evidence by condition
- Strong
- Moderate
- Limited
- Very limited
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Pre-Eclampsia Risk Moderate Improvement | Improves (the measure goes down) | Moderate effect | 4 studies | 15,730 people | ||
Studies that measured pre-eclampsia risk
| ||||||
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| PMS Symptoms Small Improvement | Improves (the measure goes down) | Small effect | 7 studies | 135 people | ||
Studies that measured pms symptoms
| ||||||
| Depression Symptoms Small Improvement | Improves (the measure goes down) | Small effect | 49 people | |||
Digestive Health
- Fecal Bile Acids: improves
- Lipid Absorption: improves
- Fecal Cholesterol: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Fecal Bile Acids Small Increase | Improves (the measure goes up) | Small effect | 1 study | 48 people | ||
Studies that measured fecal bile acids | ||||||
| Lipid Absorption | Improves (the measure goes up) | 1 study | 13 people | |||
Studies that measured lipid absorption | ||||||
| Fecal Cholesterol | Changes; see studies | 35 people | ||||
| Fecal Water Genotoxicity | Changes; see studies | 35 people | ||||
Premenstrual Syndrome (PMS)
- Depression Symptoms: improves
- Anxiety Symptoms: improves
- PMS Symptoms: changes; see studies
Infant Health
- Blood Pressure: improves
- Pre-Eclampsia Risk: changes; see studies
General Gut Health
- Fecal Bile Acids: improves
- Fecal Cholesterol: changes; see studies
- Fecal Water Genotoxicity: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Fecal Bile Acids Small Increase | Improves (the measure goes up) | Small effect | 1 study | 35 people | ||
Studies that measured fecal bile acids | ||||||
| Fecal Cholesterol | Changes; see studies | 35 people | ||||
| Fecal Water Genotoxicity | Changes; see studies | 35 people | ||||
General Cardiovascular Health
- All-Cause Mortality
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| All-Cause Mortality No effect | NoneNo effect | 1 study | 9,017 people | |||
Studies that measured all-cause mortality | ||||||
Pregnancy and Delivery Health
- All-Cause Mortality
- Pre-Eclampsia Risk: changes; see studies
- Infant Birth Weight: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| All-Cause Mortality No effect | NoneNo effect | 1 study | 30,945 people | |||
Studies that measured all-cause mortality | ||||||
| Pre-Eclampsia Risk | Changes; see studies | 4 studies | 27,442 people | |||
Studies that measured pre-eclampsia risk
| ||||||
| Infant Birth Weight | Changes; see studies | 2 studies | 14,162 people | |||
Studies that measured infant birth weight | ||||||
| Preterm Birth Risk | Improves (the measure goes down) | 16,139 people | ||||
Hormone Health
- Free Testosterone
- Testosterone: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Free Testosterone No effect | NoneNo effect | 30 people | ||||
| Testosterone | Improves (the measure goes up) | 1 study | 30 people | |||
Studies that measured testosterone | ||||||
Metabolic Health
- Free Testosterone
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Free Testosterone No effect | NoneNo effect | 30 people |
Muscle Size Strength
- Free Testosterone
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Free Testosterone No effect | NoneNo effect | 30 people |
General Athletic Performance
- Free Testosterone
- Testosterone: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Free Testosterone No effect | NoneNo effect | 30 people | ||||
| Testosterone | Improves (the measure goes up) | 1 study | 30 people | |||
Studies that measured testosterone | ||||||
Muscle Size & Strength
- Free Testosterone
- Testosterone: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Free Testosterone No effect | NoneNo effect | 30 people | ||||
| Testosterone | Improves (the measure goes up) | 1 study | 30 people |
High Blood Pressure
- Pre-Eclampsia Risk: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Pre-Eclampsia Risk | Changes; see studies | 4 studies | 15,730 people |
Cardiovascular Disease
- Blood Pressure: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Blood Pressure | Changes; see studies | 3 studies | 3,039 people |
Bone Health
- Bone Mineral Density: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Bone Mineral Density | Improves (the measure goes up) | 2 studies | 1,464 people |
Weight Loss & Maintenance
- Weight: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Weight | Changes; see studies | 1 study | 885 people |
What the published studies found
2 automated readings
LDL cholesterol
The studies read do not show a clear benefit for LDL cholesterol. One reading found evidence too weak to tell, a second reading of the same search found little or no difference. The strongest review read studied children and adolescents with familial hypercholesterolaemia. The evidence is very weak.
4 studies counted of 11 read: 3 reviews and 1 trial (53 people in the trials).
- Systematic review, 2025; 28 studies; children and adolescents with familial hypercholesterolaemia: unclear: evidence too weak to tell (the review the verdict rests on).
reductions in LDL -C ranging from 4 % (calcium carbonate)
Nutrition and dietary interventions for treatment and management of familial hypercholesterolaemia in children and adolescents: A systematic review - Meta-analysis, 2022: improves.
significant reduction in low density lipoprotein cholesterol
The effect of calcium supplement intake on lipid profile: a systematic review and meta-analysis of randomized controlled clinical trials - Systematic review, 2019; 11 studies; overweight and obese individuals: improves.
serum levels of low-density lipoprotein cholesterol (LDL-C; n = 5)
Impact of Dietary Calcium Supplement on Circulating Lipoprotein Concentrations and Atherogenic Indices in Overweight and Obese Individuals: A Systematic Review - Randomised trial, 2013; 53 people; overweight and obese college students: no clear difference.
No significant difference was detected for changes in metabolic variables
Calcium plus vitamin D3 supplementation facilitated fat loss in overweight and obese college students with very-low calcium consumption: a randomized controlled trial
- Systematic review, 2025; 28 studies; children and adolescents with familial hypercholesterolaemia: unclear: evidence too weak to tell (the review the verdict rests on).
Bone mineral density
The studies disagree. The best available review (2022, 7 studies, 1,566 people) found little or no difference in bone mineral density, while 2 of the 3 studies read found an improvement. The evidence is very weak.
3 studies counted of 11 read: 3 reviews.
- Meta-analysis, 2022; 7 studies, 1,566 people; pregnant women and their offspring: no clear difference (the review the verdict rests on).
No advantage of calcium supplementation was found
Calcium supplementation during pregnancy and maternal and offspring bone health: a systematic review and meta-analysis - Systematic review, 2022; 7 studies, 703 people; people taking TDF-based drugs: improves.
significant increase of BMD in the spine and hip
Vitamin D and Calcium Supplementation Reverses Tenofovir-Caused Bone Mineral Density Loss in People Taking ART or PrEP: A Systematic Review and Meta-Analysis - Meta-analysis, 2017; 17 studies, 2,537 people; postmenopausal women: improves. Quantitative analysis of efficacy and associated factors of calcium intake on bone mineral density in postmenopausal women
- Meta-analysis, 2022; 7 studies, 1,566 people; pregnant women and their offspring: no clear difference (the review the verdict rests on).
Key findings
- Pre-Eclampsia RiskImproves (the measure goes down)
- PMS SymptomsImproves (the measure goes down)
- Fecal Bile AcidsImproves (the measure goes up)
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Third-party tested Calcium products, in the forms the graded studies used where we can match them.
- Grade A
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Studies cited
22 studies from PubMed
- A pilot study to compare fluoxetine, calcium, and placebo in the treatment of premenstrual syndrome
- Dietary calcium and manganese effects on menstrual cycle symptoms
- Calcium in milk products precipitates intestinal fatty acids and secondary bile acids and thus inhibits colonic cytotoxicity in humans
- Faecal steroid excretion in humans is affected by calcium supplementation and shows gender-specific differences
- The effect of calcium supplementation in people under 35 years old: A systematic review and meta-analysis of randomized controlled trials.
- Calcium supplementation, bone mineral density and bone mineral content. Predictors of bone mass changes in adolescent mothers during the 6-month postpartum period
- Testosterone levels in athletes at rest and exhaustion: effects of calcium supplementation
- Effect of calcium on premenstrual syndrome: A double-blind randomized clinical trial
- Effects of calcium supplement therapy in women with premenstrual syndrome
- Calcium carbonate and the premenstrual syndrome: effects on premenstrual and menstrual symptoms. Premenstrual Syndrome Study Group
- Calcium supplementation in premenstrual syndrome: a randomized crossover trial
- Calcium, magnesium, and vitamin D supplementations as complementary therapy for hypertensive patients: a systematic review and meta-analysis.
- Calcium supplementation in nulliparous women for the prevention of pregnancy-induced hypertension, preeclampsia and preterm birth: an Australian randomized trial. FRACOG and the ACT Study Group
- World Health Organization randomized trial of calcium supplementation among low calcium intake pregnant women
- Association Between Calcium Supplementation and the Risk of Cardiovascular Disease and Stroke: A Systematic Review and Meta-Analysis.
- Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems
- Risk factors associated with preeclampsia in healthy nulliparous women. The Calcium for Preeclampsia Prevention (CPEP) Study Group
- Calcium supplementation for prevention of primary hypertension.
- Calcium supplementation (other than for preventing or treating hypertension) for improving pregnancy and infant outcomes.
- Effects of Maternal Nutritional Supplements and Dietary Interventions on Placental Complications: An Umbrella Review, Meta-Analysis and Evidence Map
- Effectiveness of calcium supplementation in the prevention of gestational hypertension: A systematic review and meta-analysis of randomised controlled trials.
- Calcium supplementation for people with overweight or obesity.