Maternal anaemia · pregnant women
It is very uncertain whether summary of findings table ‐ Vitamin B12 supplementation changes maternal anaemia compared with placebo/no vitamin B12 supplementation (very low certainty).
1 finding from 1 review
Miscarriage and spontaneous abortion · pregnant women
1 finding from 1 review
Low birthweight · pregnant women
Summary of findings table ‐ Vitamin B12 supplementation showed no clear difference in low birthweight (< 2500 g) compared with placebo/no vitamin B12 supplementation (low certainty).
1 finding from 1 review
Preterm birth · pregnant women
Summary of findings table ‐ Vitamin B12 supplementation showed no clear difference in preterm birth (< 37 weeks) compared with placebo/no vitamin B12 supplementation (low certainty).
1 finding from 1 review
Child cognitive outcomes · pregnant women
1 finding from 1 review
Neural tube defects ‐ not reported · pregnant women
The review found no eligible studies for this question.
1 finding from 1 review
no estimate extracted
Studies not reported
No studies found
Clinical response · people with inflammatory bowel disease
The review found no eligible studies for this question.
1 finding from 1 review
no estimate extracted
Studies not reported
No studies found
Clinical relapse · people with inflammatory bowel disease
High‐treatment‐dose vitamin D (greater than 1000 IU/day) showed no clear difference in clinical relapse at end of study (52 weeks) compared with low‐treatment‐dose vitamin D (400 IU/day to 1000 IU/day) (low certainty).
1 finding from 1 review
Quality of life · people with inflammatory bowel disease
1 finding from 1 review
Withdrawals due to adverse events · people with inflammatory bowel disease
It is very uncertain whether high‐treatment‐dose vitamin D (greater than 1000 IU/day) changes withdrawals due to adverse events compared with low‐treatment‐dose vitamin D (400 IU/day to 1000 IU/day) (very low certainty).
1 finding from 1 review
Cognitive function · cognitively healthy people in mid and late life
2 findings from 1 review
Incidence of MCI or all‐cause dementia ‐ not measured · cognitively healthy people in mid and late life
The review found no eligible studies for this question.
1 finding from 1 review
no estimate extracted
Studies not reported
No studies found
Frequency of leg cramps after treatment: never · treating leg cramps in pregnancy
1 finding from 1 review
Prostate cancer · Adults (general population)
Meta-analysis of observational studies (higher vs lower 25(OH)D) for Prostate cancer: OR 1.04 (95% CI 0.98 to 1.09), not statistically significant. Umbrella review outcome-level evidence grade: Substantial effect unlikely.
1 finding from 1 review
Type 2 diabetes mellitus · Adults (general population)
Meta-analysis of observational studies (higher vs lower 25(OH)D) for Type 2 diabetes: OR 0.63 (95% CI 0.56 to 0.69), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.
1 finding from 1 review
Sporadic colorectal adenoma recurrence · Adults (general population)
Meta-analysis of observational studies (higher vs lower 25(OH)D) for Sporadic colorectal adenoma recurrence: OR 0.87 (95% CI 0.57 to 1.33), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.
1 finding from 1 review
Ischaemic heart disease · Adults (general population)
Meta-analysis of observational studies (higher vs lower 25(OH)D) for Ischaemic heart disease: HR 0.72 (95% CI 0.65 to 0.81), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.
1 finding from 1 review
Breast cancer · Adults (general population)
Meta-analysis of observational studies (higher vs lower 25(OH)D) for Breast cancer (Premenopausal): RR 1.01 (95% CI 0.97 to 1.06), not statistically significant. Umbrella review outcome-level evidence grade: Substantial effect unlikely.
3 findings from 1 review
RR 1.01 [0.97, 1.06]
6 studies · 2890 participants
GRADE not reported
RR 0.99 [0.97, 1.01]
9 studies · 8766 participants
GRADE not reported
OR 0.55 [0.42, 0.71]
21 studies · 26317 participants
GRADE not reported
All cause mortality · people with chronic kidney disease (predialysis (GFR 15 to 60 mL/min/1.73 m²), HD, PD, transplant recipients)
Meta-analysis of observational studies (higher vs lower 25(OH)D) for All cause mortality, Patients with chronic kidney disease: RR 0.86 (95% CI 0.81 to 0.92), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.
1 finding from 1 review
Metabolic syndrome (prevalent) · Adults (general population)
Meta-analysis of observational studies (higher vs lower 25(OH)D) for Metabolic syndrome (prevalent): OR 0.49 (95% CI 0.38 to 0.64), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.
1 finding from 1 review