What do systematic reviews say?

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

The review found no eligible studies for this question.

• Vitamin B12 supplementation during pregnancy for maternal and child health outcomes 2024 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

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

The review found no eligible studies for this question.

• Vitamin D for the treatment of inflammatory bowel disease 2023 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

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

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).

• Vitamin D for the treatment of inflammatory bowel disease 2023 · Cochrane Headline outcomes only
  RR 0.48 [0.23, 1.01]
  1 study · 34 participants
  Low

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

• Vitamin D for the treatment of inflammatory bowel disease 2023 · Cochrane Headline outcomes only
  no estimate extracted
  1 study · 46 participants
  Very low

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

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).

• Vitamin D for the treatment of inflammatory bowel disease 2023 · Cochrane Headline outcomes only
  RR 0.89 [0.06, 13.08]
  3 studies · 104 participants
  Very low

Multivitamin vs control

• Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late… 2018 · Cochrane Headline outcomes only
  no estimate extracted
  1 study · 5947 participants
  Low
• Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late… 2018 · Cochrane Headline outcomes only
  no estimate extracted
  1 study · 2324 participants
  Low

Multivitamin vs control

The review found no eligible studies for this question.

• Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late… 2018 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Oral vitamin B vs no treatment

• Interventions for leg cramps in pregnancy 2020 · Cochrane Headline outcomes only
  no estimate extracted
  0 studies · 0 participants
  GRADE not reported

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

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.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  OR 1.04 [0.98, 1.09]
  14 studies · 28988 participants
  GRADE not reported

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

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.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  OR 0.63 [0.56, 0.69]
  16 studies · 72204 participants
  GRADE not reported

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

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.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  OR 0.87 [0.57, 1.33]
  3 studies · 1366 participants
  GRADE not reported

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

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.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  HR 0.72 [0.65, 0.81]
  19 studies · 82982 participants
  GRADE not reported

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

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.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes

  Premenopausal
  RR 1.01 [0.97, 1.06]
  6 studies · 2890 participants
  GRADE not reported
• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes

  Postmenopausal
  RR 0.99 [0.97, 1.01]
  9 studies · 8766 participants
  GRADE not reported
• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  OR 0.55 [0.42, 0.71]
  21 studies · 26317 participants
  GRADE not reported

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

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.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes

  Patients with chronic kidney disease
  RR 0.86 [0.81, 0.92]
  10 studies · 6853 participants
  GRADE not reported

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

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.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  OR 0.49 [0.38, 0.64]
  8 studies · 31416 participants
  GRADE not reported

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

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Cognition: OR 0.42 (95% CI 0.34 to 0.53), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  OR 0.42 [0.34, 0.53]
  7 studies · 9004 participants
  GRADE not reported

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

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Pancreatic cancer: OR 2.13 (95% CI 1.02 to 4.47), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  OR 2.13 [1.02, 4.47]
  6 studies · 2113 participants
  GRADE not reported

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

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Hip fracture (Population-based controls): log ratio of geometric mean -0.51 (95% CI -0.64 to -0.38), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes

  Population-based controls
  log ratio of geometric mean -0.51 [-0.64, -0.38]
  9 studies · 1655 participants
  GRADE not reported
• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes

  Hospital-based controls
  log ratio of geometric mean -0.26 [-0.33, -0.23]
  8 studies · 2201 participants
  GRADE not reported

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

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Non-Hodgkin's lymphoma (Females): OR 0.81 (95% CI 0.39 to 1.70), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes

  Females
  OR 0.81 [0.39, 1.70]
  4 studies · 39 participants
  GRADE not reported
• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes

  Males
  OR 0.65 [0.35, 1.23]
  6 studies · 65 participants
  GRADE not reported

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

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Hypertension: RR 0.70 (95% CI 0.58 to 0.86), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

• Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
  RR 0.70 [0.58, 0.86]
  7 studies · 48633 participants
  GRADE not reported