Writing in BMC Public Health, Chinese researchers reviewed data from the U.S. National Health and Nutrition Examination Survey (NHANES) between 1999 and 2006.
“Our present study drew a distinct conclusion, establishing a positive correlation between dietary zinc intake and the occurrence of endometriosis,” they wrote. “Differences in the absorption and metabolism of zinc between blood and urine may be the cause of this discrepancy.”
They also noted that further study of zinc intake levels should be examined to determine efficacy of the mineral.
A critical role to play
Women experience endometriosis, a common inflammatory condition, when endometrial tissue forms outside the uterus on organs and tissues within the pelvic area. The condition impacts 176 million women globally, and nearly 10% of fertile women experience related pain. As a public health issue, women with endometriosis shoulder double the healthcare costs than those without the condition, according to the researchers.
The study noted that zinc, an essential trace mineral, plays a critical role play in the reproductive tract, where it promotes DNA synthesis, cell division and gene expression. As the human body cannot store zinc, regular dietary intake is needed and for people of reproductive age. Essentially, a shortage in zinc can result in changes in immune cell counts as well as promotion of pathogens, raising the risk of several conditions. Deficiency can also lead to hormonal imbalances that impact gonadal development and ovarian function.
“While most studies have focused on zinc's role and supplementation during pregnancy and fetal development, only a few clinical studies suggest decreased serum zinc levels in women with endometriosis,” the researchers wrote. “However, these studies, with their low sample numbers, have limitations, and the impact of factors such as smoking, obesity and race/ethnicity remains unknown…Our findings aim to provide new insights into endometriosis prevention strategies in the United States.”
Study details
The study included 4,315 women between the ages of 20 and 54 years. After determining through a health questionnaire whether participants had endometriosis (331 were diagnosed), the researchers used an NHANES dietary survey (a 24-hour recall prior to completing the study interview) to record what patients ate and whether zinc consumption was part of that diet.
Researchers then randomized participants into data collection sessions following the initial 24-hour recall investigation. Using the U.S. Department of Agriculture Survey Nutrients Database and the University of Texas Food Intake Analysis System, they determined dietary zinc and nutrient consumption prior to conducting two 24-hour dietary recall interviews and a second interview 3 to 10 days later by phone.
“To date, a limited number of studies have explored the association between zinc and endometriosis, with varying results,” the researchers wrote. “While our results suggest a positive correlation between higher dietary zinc intake and lower endometriosis risk, some findings did not reach statistical significance.”
The odds ratio values for dietary zinc intake and endometriosis in the 8–14 mg/day and > 14 mg/day groups were 1.19 (95% CI: 0.92–1.54, p = 0.189) and 1.60 (95% CI: 1.12–2.27, p = 0.009), respectively. The association between zinc intake and endometriosis risk for women who took 8–14 mg/day was not significant.
“This indicates that the protective effect of zinc may not be consistent across all intake levels, suggesting the need for further research on potential threshold effects,” they noted.
Source: BMC Public Health
doi: 10.1186/s12889-024-20433-9
“Exploring the link between dietary zinc intake and endometriosis risk: insights from a cross-sectional analysis of American women”
Authors: Yingmei Huang et al.