Effects of curcumin supplementation on vitamin D levels in women with premenstrual syndrome and dysmenorrhea: a randomized controlled study

Randomized controlled trial in young women aged 18 to 24 years with a history of moderate to severe premenstrual syndrome and dysmenorrhea. The curcumin arm had 38 participants randomized, with 36 completed and analyzed. Participants were recruited from dormitories of 4 universities in Birjand, South-Eastern Iran, between January 2020 and March 2020.

The active regimen was one oral capsule daily containing 500 mg curcuminoids (C3 Complex) plus 5 mg piperine (Bioperine) for 10 days per menstrual cycle, starting 7 days before and continuing through 3 days after the estimated onset of menstruation, for 3 menstrual cycles. The placebo capsules were identical in appearance and contained lactose powder with 5 mg piperine.

Curcumin improved serum 25-hydroxyvitamin D within the active arm, but the vitamin D benefit was not significant versus placebo overall. In the curcumin group, 25-hydroxyvitamin D increased from 12.8 ng/mL (7.0-24.6) to 16.2 ng/mL (6.4-28.8), P = 0.045; in placebo, it changed from 18.6 ng/mL (2.2-26.8) to 21.3 ng/mL (5.2-27.1), P = 0.17. Vitamin D status improved in 25% of the curcumin group versus 18% of placebo participants, with between-group p = 0.71. Curcumin also reduced AST (P = 0.040) and direct bilirubin (P = 0.021), while fasting blood glucose and lipid profiles were not significantly affected. Rash-related side effects caused 2 withdrawals in the curcumin group.

The intervention was short, spanning only 3 menstrual cycles, and the analyzed active-arm sample was small. The primary vitamin D status improvement was not significant versus placebo, and the study was conducted in a narrow population of young university women from one region in Iran, limiting generalizability. Rash-related dropouts also indicate some tolerability concerns.