A randomised controlled trial of the effects of curcumin on nitric oxide levels in women with premenstrual syndrome and dysmenorrhoea

Introduction: Symptoms of primary dysmenorrhoea (PD) and premenstrual syndrome (PMS) are common gynaecologic complaints in women. It has been proposed that they may be related to nitric oxide (NO) release. We aimed to investigate the effects of curcumin, as an anti-inflammatory and antioxidant natural product, on the levels of serum NO metabolites in young women with PD and PMS. Methods: A randomised, triple-blinded, placebo-controlled clinical trial was performed. Women who suffered from both PMS and PD were enroled and received curcumin (n = 38), or placebo (n = 38), as capsules daily (500 mg of curcuminoid plus piperine, or placebo) from 7 days pre-until 3 days postmenstruation for three successive menstrual cycles. The dietary intake, as well as biochemical and haematological parameters was evaluated by standard procedures. Serum NOx (nitrite & PLUSMN; nitrate) was measured using the Griess assay. Results: At baseline, there were no significant differences between the curcumin and placebo groups with respect to age, dietary intake, and NOx levels. A significant decrement was found in serum concentrations of NOx (93.3 & PLUSMN; 37.4 to 85.9 & PLUSMN; 28.9; P = 0.048) after curcuminoid supplementation, but this was not the case for the placebo group, NOx levels remained unaltered by the end of the trial (72.4 & PLUSMN; 42.5 to 68.4 & PLUSMN; 32.9; P = 0.32). However, the between-group analysis showed no significant differences in the NOx index (P = 0.36). A significant direct correlation was found between PMS pain and NOx levels only in the curcumin group (Pearson's r = 0.34; P = 0.042). Conclusions: Curcuminoid-piperine supplementation may cause a reduction in serum NOx levels in young women with PD and PMS.