High vitamin D concentrations help limit fibroid growth

04 Oct 2022 bởiJairia Dela Cruz
High vitamin D concentrations help limit fibroid growth

Uterine fibroid growth appears to be slower in women with 25(OH)D concentrations ≥20 ng/mL, as reported in a study.

In a cohort of 1,610 women, those with serum 25(OH)D ≥20 vs <20 ng/mL had an estimated 9.7-percent reduction in fibroid growth rate (95 percent confidence interval [CI], –17.3 to –1.3) over 5 years of follow-up. [Fertil Steril 2022;doi:10.1016/j.fertnstert.2022.08.851]

Meanwhile, there was evidence of fibroid development prevention (adjusted hazard ratio, 0.78, 95 percent CI, 0.47–1.30) as well as fibroid loss (adjusted risk ratio, 1.32, 95 percent CI, 0.95–1.83) in the group of women with serum 25(OH)D ≥30 vs <30 ng/mL.

“Our findings for reduced growth of fibroids from participants with higher 25(OH)D levels are consistent with results of small clinical trials that treated participants with vitamin D supplements, although most of those studies included participants with 25(OH)D concentrations ranging up to 30 ng/mL at enrolment and treated with supplementation that would have resulted in higher concentrations than generally seen in our sample,” according to the investigators. [Complement Ther Clin Pract 2020; 39:101159; Caspian J Intern Med 2019;10:125-131; Medicine 2016;95:e5698; Int J Fertil Steril 2021;15:95-100]

As shown in previous studies, vitamin D may limit fibroid growth by causing changes in cell proliferation, apoptosis, extracellular matrix composition, Wnt/β-catenin, and TGFβ3 expression, and downregulation of oestrogen and progesterone receptors. [Nutrients 2021;13:597; J Clin Endocrinol Metab 2015;100:E572-E582; Fertil Steril 2021;115:512-521; Reprod Sci 2014;21:1108-1119; Fertil Steril 2019;111:397-407]

“Fibroid loss was not included as an outcome in the trials of fibroid growth. However, if our finding of reduced fibroid growth with higher vitamin D results in some fibroids shrinking below the ultrasound detection limit, increased fibroid loss would be expected,” the investigators said.

Small fibroids matter

The study population comprised self-identified African American or Black women without previous clinical diagnosis of fibroids. Their mean age was 29.2 years, and 24 percent had body mass index ≥40 kg/m2. Participants had low 25(OH)D concentrations throughout the 5-year study duration. The median concentrations were 15.3 ng/mL at enrolment, 14.8 ng/mL at follow-up 1, and 15.3 ng/mL at follow-up 2.

Based on 25(OH)D measures across the study, 32 percent of the women were deficient (<12 ng/mL), 41 percent had 12 to <20 ng/mL, 27 percent had ≥20 ng/mL. Only 7 percent of women exceeded the Endocrine Society cutoff point for vitamin D sufficiency (≥30 ng/mL). Very few (1.7 percent) of the women had concentrations ≥30 ng/mL at all three visits.

At baseline, 23 percent of the women had at least one fibroid (median, one fibroid; 75th percentile, two fibroids), with this proportion increasing to 32 percent by the end of the study (median, two fibroids; 75th percentile, three fibroids). The median volume of the incident fibroids at time of first detection was 0.56 cm3, while the median volume for those followed for growth was 2.2 cm3. Overall estimated fibroid growth averaged 77.0 percent volume increase per 18 months.

“Although most fibroids in this cohort were small and might not warrant immediate clinical attention, our study still has important clinical implications [given that] symptoms and major interventional treatments are more likely with larger fibroids,” the investigators pointed out. [Obstet Gynecol 2003;101:431-437; Hum Reprod 2015;30:2936-2944]

“Therefore, minimizing fibroid growth and increasing fibroid loss when fibroids are small can delay severe morbidity and prevent the need for surgical or radiologic treatments,” they added.

The investigators acknowledged that the study had limited power to detect associations at higher concentrations of 25(OH)D due to the small number of women (1.7 percent) who maintained 25(OH)D concentrations ≥30 ng/mL throughout the study.

“Interventional trials that raise and maintain 25(OH)D concentrations >30ng/mL and then prospectively monitor fibroid development are needed to further assess supplemental vitamin D efficacy and determine optimal treatment protocols,” they said.