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Evidence found and GRADE certainty

780 questions · 834 findings · 76 reviews

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No studies found 187 · 22.4%GRADE not reported 164 · 19.7%Very low 144 · 17.3%Low 172 · 20.6%Moderate 105 · 12.6%High 62 · 7.4%

Any‐treatment‐dose vitamin D (greater than 400 IU/day) vs supplemental‐dose vitamin D (less than 400 IU/day)

Withdrawals due to adverse events · people with inflammatory bowel disease

It is very uncertain whether any‐treatment‐dose vitamin D (greater than 400 IU/day) changes withdrawals due to adverse events compared with supplemental‐dose vitamin D (less than 400 IU/day) (very low certainty).

1 finding from 1 review

Summary of findings table ‐ Vitamin B12 supplementation vs no supplementation or placebo

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

Summary of findings table ‐ Vitamin B12 supplementation vs no supplementation or placebo

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

Summary of findings table ‐ Vitamin B12 supplementation vs no supplementation or placebo

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

High‐treatment‐dose vitamin D (greater than 1000 IU/day) vs low‐treatment‐dose vitamin D (400 IU/day to 1000 IU/day)

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

High‐treatment‐dose vitamin D (greater than 1000 IU/day) vs low‐treatment‐dose vitamin D (400 IU/day to 1000 IU/day)

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

Multivitamin vs control

Cognitive function · cognitively healthy people in mid and late life
2 findings from 1 review

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

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

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

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

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

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