Vitamin D and Increased Vitamin D Level

Research synthesisModerate evidenceMixed effect size3 studies · 3 beneficial · 0 neutral · 0 harmful

Across 3 studies, all reported beneficial effects on increasing vitamin D levels, with effect sizes ranging from small to large (mixed). The most robust evidence comes from a meta-analysis of 613 pregnant women (MD=32.42 nmol/L, large effect) and an RCT in vitamin D deficient adults (large effect). The evidence base is small and preliminary.

Studied populations: pregnant women, lactating women, and vitamin D deficient adults

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Available evidence is overwhelmingly positive, which may reflect publication bias (null-result studies less likely to be published). Study durations were not consistently reported, and effect sizes varied (one systematic review of lactating women found only a small effect).

Generated Jul 13, 2026

Doses used in studies

IU single-dose: 25,000 (median 25,000, IQR 25,000–25,000) — 1 study

3 of 3 papersPopulation:

Efficacy of vitamin D supplementation on the incidence of preeclampsia: a systematic review and meta-analysis.
- 2024-12-23
- Meta-Analysis · n = 613
- BMC pregnancy and childbirth 24(1)
- - Khaled Moghib
  - Thoria I Ghanm
  - Abdallah Abunamoos
  - Munia Rajabi
  - Shehab M Moawad
  - Ahmed Mohsen
  - Said Kasem
  - Khalid Elsayed
  - Moaaz Sayed
  - Ali I Dawoud
  - Izere Salomon
  - Alaaeldin Elmaghreby
  - Mohamed Ismail
  - Ahmed Amer
- PubMed: 39716171
- DOI: 10.1186/s12884-024-07081-y
5 Insights on
- Increased Vitamin D Level
- High evidence
- Pregnant Women
Serum 25-hydroxyvitamin D levels significantly increased in the supplementation group (MD = 32.42 nmol/L, 95% CI [20.33, 44.50], P < 0.0001)
Effect
Beneficial
Effect size
Large
Significant
Yes
Dose
varying doses
Short-Term Effects of Escalating Doses of Cholecalciferol on FGF23 and 24,25(OH)2 Vitamin D Levels: A Preliminary Investigation.
- 2024-10-23
- RCT
- Nutrients 16(21)
- - Jessica Pepe
  - Luciano Colangelo
  - Roberta Pilotto
  - Viviana De Martino
  - Carla Ferrara
  - Alfredo Scillitani
  - Mirella Cilli
  - Salvatore Minisola
  - Ravinder Singh
  - Cristiana Cipriani
- PubMed: 39519433
- DOI: 10.3390/nu16213600
10 Insights on
- Increased Vitamin D Level
- High evidence
- Rigorous Journal
- Clinical
In the group administered 600,000 I.U., there was a significant increase in the delta changes in 25(OH)D and 1,25(OH)2D compared to the placebo and in the delta 24,25(OH)D2 compared to the placebo and 25,000 I.U. groups (all p < 0.05).
Effect
Beneficial
Effect size
Large
Significant
Yes
Dose
600,000 I.U. single oral dose
Evaluating the relationship between the nutrient intake of lactating women and their breast milk nutritional profile: a systematic review and narrative synthesis.
- 2023-12-06
- Systematic Review
- The British journal of nutrition 131(7)
- - Coralie Falize
  - M Savage
  - Yvonne M Jeanes
  - Simon C Dyall
- PubMed: 38053371
- DOI: 10.1017/s0007114523002775
13 Insights on
- Increased Vitamin D Level
- High evidence
some evidence of response for ... vitamin C and D...
Effect
Beneficial
Effect size
Small
Significant
Yes

Vitamin D and Increased Vitamin D Level

Efficacy of vitamin D supplementation on the incidence of preeclampsia: a systematic review and meta-analysis.

Short-Term Effects of Escalating Doses of Cholecalciferol on FGF23 and 24,25(OH)2 Vitamin D Levels: A Preliminary Investigation.

Evaluating the relationship between the nutrient intake of lactating women and their breast milk nutritional profile: a systematic review and narrative synthesis.