Effect of vitamin D supplementation on symptoms severity in vitamin D insufficient women with premenstrual syndrome: A randomized controlled trial

Background: Premenstrual syndrome (PMS) is one of the most prevalent disorders among reproductive women worldwide that negatively impact women's quality of life. This study aimed to investigate the effect of vitamin D supplementation on the severity of PMS symptoms in vitamin D insufficient women with PMS.Methods: In this randomized, double-blind clinical trial, 44 vitamin D insufficient women with PMS received either 50,000 IU vitamin D or a placebo fortnightly for 16 weeks. Participants completed the PMS Daily Symptoms Rating form at beginning and during the last two months of the intervention, and their blood samples were collected to assess 25(OH)D serum levels.Results: After the four months' intervention, the serum level of 25(OH)D in the vitamin D group raised from 21 +/- 8 ng/ml to 40 +/- 8 ng/ml (P < 0.001), while in the placebo group it raised from 21 +/- 7 ng/ml to 23 +/- 7 ng/ml (P = 0.03). Indeed, serum vitamin D levels in the placebo group could not reach a sufficient level. At the end of the intervention, the mean score of total PMS symptoms showed significant improvement in the vitamin supplemented group compared to the controls (p < 0.001). By grouping the PMS symptoms into five subgroups, the mean score of all five subgroups decreased post-supplementation compared to the baseline; however, the highest and lowest decrease were in depression (53 %) and water retention subgroups (28 %), respectively. This indicates a greater improvement in the mean scores of mood symptoms compared to physical symptoms in this study (p < 0.001).Conclusion: Results obtained in this clinical trial represent the helpful effects of vitamin D supplementation on total, physical and mood symptoms in vitamin D insufficient women with PMS.Trial registration: This randomized controlled trial at IRCT.ir on 2018-06-20 with Registration No: IRCT20180525039822N1.(c) 2023 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.