The Role of Vitamin D Oral Supplementation in Insulin Resistance in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
What this study found
Overall, vitamin D supplementation did not show a significant effect on fasting glucose or fasting insulin across all trials, but it may improve insulin sensitivity in selected subgroups. HOMA-IR improved in studies using low daily doses, typically under 4000 IU/d, and in co-supplementation regimens with other micronutrients. The authors concluded that vitamin D may be beneficial for insulin resistance in PCOS when used as a co-supplement or as continuous low daily dosing, but the evidence is not consistent enough for a clear overall effect. Some higher-dose or heterogeneous regimens showed…
- Study & population
- Systematic review and meta-analysis of randomized controlled trials in women with polycystic ovary syndrome.
- Intervention
- Oral vitamin D supplementation was evaluated across randomized trials in women with PCOS, given either alone or with other micronutrients.
- Key limitation
- The evidence base was heterogeneous in dose, formulation, duration, and co-supplement use, which limited comparability across trials.
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Open PDFOriginal abstract
Objective: To evaluate the effect of vitamin D supplementation (alone or with co-supplementation) on insulin resistance in patients with polycystic ovary syndrome (PCOS). Methods: We performed a literature search of databases (Medline, Scopus, Web of Knowledge, Cochrane Library) and identified all reports of randomized controlled trials (RCTs) published prior to April 2018. We compared the effects of supplementation with vitamin D alone (dose from 1000 IU/d to 60,000 IU/week) or with co-supplements to the administration of placebos in women diagnosed with PCOS. The systematic review and meta-analysis protocol was registered in the International Prospective Register of Systematic Reviews (Prospero) as number CRD42018090572. Main results: Eleven of 345 identified studies were included in the analysis; these involved 601women diagnosed with PCOS. Vitamin D as a co-supplement was found to significantly decrease fasting glucose concentrations and the HOMA-IR value. HOMA-IR also declined significantly when vitamin D was supplemented with a dose lower than 4000 IU/d. Conclusions: Evidence from RCTs suggests that the supplementation of PCOS patients with continuous low doses of vitamin D (<4000 IU/d) or supplementation with vitamin D as a co-supplement may improve insulin sensitivity in terms of the fasting glucose concentration (supplementation with vitamin D in combination with other micronutrients) and HOMA-IR (supplementation with vitamin D in continuous low daily doses or as co-supplement).