Plain language summary
Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting more than 10% of women of reproductive age and is associated with an increase in cardiovascular risk factors, metabolic syndrome, cardiovascular diseases and non-alcoholic fatty liver disease (NAFLD). The aim of this double-blind, randomized, placebo-controlled study was to explore the effects of vitamin D supplementation on cardiovascular risk factors, hormones, glucose metabolism and markers of liver injury and fibrosis in overweight and obese vitamin D deficient women with PCOS. 40 participants were randomised to take either 3200iu vitamin D or placebo daily for 3 months. Vitamin D levels significantly increased over the three months in both groups but statistically significantly more so in women receiving vitamin D compared to placebo. Women receiving vitamin D had normal vitamin D levels after three months of supplementation whilst women in the placebo group remained within the insufficiency range. The only significant improvement that was statistically significantly better in the vitamin D group compared to placebo group was a decrease in alanine transaminase (ALT, a marker of liver function). Weak improvements in insulin sensitivity and liver fibrosis markers were also observed but these were not statistically significantly better than in the placebo group.
Abstract
Polycystic ovary syndrome (PCOS) increases the risk of metabolic syndrome and non-alcoholic-fatty-liver disease (NAFLD). Vitamin D supplementation may exert positive effects on liver biochemistry in patients with NAFLD; however, its effects on PCOS are unknown. This randomized, double-blind, placebo-controlled study explored the effect of vitamin D supplementation on cardiovascular risk factors (high-sensitivity C-reactive protein (hs-CRP), weight, body mass index (BMI), lipid profile, glucose levels, insulin levels, the homeostatic model assessment-insulin resistance (HOMA-IR), hormones (free androgen index (FAI), testosterone, sex hormone binding globulin (SHBG), and liver markers (alanine aminotransferase (ALT), hyaluronic acid (HA), N-terminal pro-peptide of type III procollagen (PIIINP), tissue inhibitor of metallo-proteinases-1 (TIMP-1), and the enhanced liver fibrosis (ELF) score). Forty women with PCOS were recruited and randomized to vitamin D (3200 IU) or placebo daily for 3 months. All outcomes were measured at baseline and 3 months follow-up (FU). Greater increases in vitamin D levels were shown in the supplementation group (vitamin D, baseline: 25.6 ± 11.4 nmol/L, FU: 90.4 ± 19.5 nmol/L vs. placebo, baseline: 30.9 ± 11.1 nmol/L, FU: 47.6 ± 20.5 nmol/L, p < 0.001). Between groups comparisons (% baseline change) revealed significant differences in ALT (p = 0.042) and a weak effect indicating a greater reduction in the HOMA-IR in the vitamin D group (p = 0.051). No further between group differences were seen in other cardiovascular risk factor, liver markers, or hormones. This study supports beneficial effects of vitamin D supplementation on liver markers and modest improvements in insulin sensitivity in vitamin D deficient women with PCOS.
Methodological quality
Jadad score
:
4
Allocation concealment
:
Yes
