Table 2.
Effect of calcium intake on health outcomes. Evidence from randomised controlled trials (RCT) and systematic reviews of randomised controlled trials.
| Health Outcomes | Outcome | Population Group | Research Evidence | Effect Size |
|---|---|---|---|---|
| Hypertensive disorders of pregnancy | Preeclampsia | Pregnant women | Meta-Analysis | Calcium supplementation compared to placebo reduced the risk of preeclampsia, RR 0.45, (95% CI: 0.31 to 0.65) [48]. |
| Pregnant women with low basal calcium intake | Meta-Analysis | Calcium supplementation compared to placebo reduced the risk of preeclampsia, RR 0.36, (95% CI: 0.20 to 0.65) [48]. | ||
| High blood pressure | Pregnant women | Meta-Analysis | Calcium supplementation compared to placebo reduced the high blood pressure relative risk (RR) to 0.65, (95% CI: 0.53 to 0.81) [48]. | |
| Blood pressure | Blood pressure | Normotensive adults | Meta-Analysis | Calcium supplementation reduced systolic blood pressure (SBP) in adults by 1.14 mmHg (95% CI: −2.01 to −0.27) with doses of calcium 1000 to 1500 mg/day and by 2.79 mmHg (95% CI: −4.71 to −0.86) with doses of calcium equal to or over 1500 mg/day. Calcium supplementation had the greatest effect in young adults of less than 35 years as their SBP was reduced by 2.11 mmHg (95%CI: −3.58 to −0.64) [45]. |
| Blood pressure | Hypertensive adults | Calcium supplementation reduced SBP by −1.86 mm Hg (95% CI: −2.91 to −0.81) and diastolic BP (DBP) by −0.99 mm Hg (95% CI: −1.61 to −0.37) [46]. | ||
| Blood pressure | Hypertensive adults with low basal calcium intake | In people with relatively low calcium intake (≤ 800 mg per day) calcium supplementation reduced SBP by −2.63 (95% CI: −4.03 to −1.24) and DBP by −1.30 (95% CI: −2.13 to −0.47) [46]. | ||
| Blood pressure | Hypertensive adults | Calcium supplementation as compared to control induced a statistically significant reduction in SBP (mean difference: −2.5 mmHg, 95% CI: −4.5 to −0.6, I(2)= 42%) but not DBP (mean difference: −0.8 mmHg, 95% CI: −2.1 to 0.4, I(2) = 48%) [47]. | ||
| Progeny blood pressure | High blood pressure | Pregnant women/children | RCT | Calcium supplementation showed that children whose mothers received calcium supplementation had, at seven years of age, a reduction in the risk of high blood pressure (above the 90th percentile) in comparison with children whose mothers were in the placebo group (RR 0.59; 95% CI: 0.39 to 0.90) [55]. |
| Cholesterol | LDL and HDL Cholesterol | Adults | Meta-Analysis | Calcium supplementation reduced low-density lipoprotein (LDL) cholesterol [−0.12 mmol/L (95% CI: −0.22 to −0.02)] and increased high-density lipoprotein (HDL) cholesterol [0.05 mmol/L (95% CI: 0.00 to 0.10) [59]. |
| Colorectal adenomas | Recurrent colorectal adenomas | Adults with previous adenomas | Meta-Analysis | Calcium supplementation with doses from 1200 to 2000 mg/day and treatment duration from 36 to 60 months reduced the risk of recurrent colorectal adenomas, RR = 0.89, (95%CI: 0.82–0.96) [65]. |
| Bone health | Bone mineral density | Children | Meta-Analysis | Calcium supplementation had a small effect on total body bone mineral content (standardised mean difference 0.14, 95% CI: 0.01 to 0.27) and upper limb bone mineral density (0.14, 95% CI: 0.04 to 0.24), and this effect persisted after the end of supplementation only in the upper limb (0.14, 95% CI: 0.01 to 0.28) [61]. |
| Renal stones | Urolithiasis | Individuals with osteoporosis | Meta-Analysis | Calcium supplementation compared to placebo, RR 0.66 [95% CI 0.19, 2.34]; 5 studies in postmenopausal or elderly women including 2038 subjects [70]. |
| Urolithiasis | Pregnant women | Meta-Analysis | Calcium supplementation during pregnancy did not increase the risk of urolithiasis, RR 1.52 [95% CI: 0.06, 40.67] or renal colic, RR 1.75 [95% CI; 0.51, 5.99] in 2 studies with 12901 women [71]. |