Study finds higher intake of dietary antioxidants may reduce the risk of infertility in women, highlighting the role of oxidative stress in reproductive health.
Study: Impact of dietary antioxidants on female infertility risk: evidence from NHANES. Image Credit: New Africa/Shutterstok.com
In a recent study published in Scientific Reports, researchers analyzed the relationship between women’s intake of dietary antioxidants and their risk of infertility.
Their findings suggest consuming higher amounts of antioxidants in the diet may reduce the risk of infertility among women.
Background
Estimates suggest that between 8% and 12% of couples of reproductive age struggle with infertility, which is defined as the inability to achieve pregnancy after 12 months of unprotected intercourse, making it an important issue affecting public health around the world. Many cases are linked to female-specific factors, affecting millions of people worldwide.
Researchers have found that imbalances between a free radical, reactive oxygen species, and the body’s antioxidants can cause oxidative stress, which has been linked to female infertility.
Oxidative stress adversely affects reproductive processes such as follicle development, endometrial receptivity, and oocyte quality. This highlights the role of antioxidants in promoting reproductive health.
Specifically, vitamin A supports gene expression related to development, while vitamin C neutralizes harmful radicals through antioxidant pathways. Vitamin E protects cell membranes. Zinc and selenium are essential components of antioxidant enzymes that protect cells from antioxidant damage.
Antioxidant consumption can be assessed through the Composite Dietary Antioxidant Index (CDAI), which measures dietary antioxidants, including carotene, selenium, zinc, and vitamins A, C, and E.
Antioxidant intake is adjusted by the total intake of energy, accounting for diverse diets and caloric requirements to allow for comparisons across populations.
About the study
Researchers hypothesized that having a diet rich in antioxidants, indicated by a higher CDAI score, could reduce oxidative stress and protect reproductive tissues, thus reducing infertility.
They used data from the National Health and Nutrition Examination Survey (NHANES), collected across the United States between 2013 and 2018, to explore this relationship.
After excluding all males, women under or above reproductive age, and people with relevant missing data, the sample comprised 2,162 people. Participants’ CDAI (from six antioxidants—vitamins A, C, E, selenium, carotenoids, and zinc) was measured by two dietary recall interviews, during which they were asked what they had consumed in the past 24 hours.
Infertility was assessed using two targeted questions in the survey. The analysis used statistical models to determine the relationship between CDAI and infertility and adjusted for lifestyle factors such as alcohol use or smoking, physical activity, health conditions like hypertension or diabetes, income, education, marital status, ethnicity, and age.
Findings
The study found that 13.5% of the included participants reported experiencing female infertility.
People who reported infertility were significantly different in terms of their CDAI levels, health conditions like hypertension, income, marital status, and age.
Specifically, women who experienced infertility showed higher levels of CDAI (particularly carotenoids, selenium, and vitamin C) but were more likely to have health conditions such as diabetes and hypertension.
The initial crude model found no association between antioxidant intake and infertility. However, once the model was adjusted for various factors, results indicated that a higher CDAI showed a significant relationship with a reduced risk of infertility, suggesting a linear negative relationship. Selenium and vitamin C specifically were found to be protective against infertility.
These negative associations between CDAI and infertility were remarkably consistent across the subgroups, including lifestyle factors, health conditions, education, ethnicity, and age.
Notably, the link appeared more pronounced in groups experiencing earlier menarche (between 11 and 13), heavy drinkers, and those not reporting recreational activities, but these were not statistically significant.
This study provides a diverse and representative sample of the American population, making its findings broadly relevant. Using CDAI as a measure of antioxidant intake allows the findings to capture the combined effects and interactions between multiple antioxidants.
However, its cross-sectional design prevents researchers from establishing causality, and its reliance on self-reported dietary data may lead to inaccuracies or bias.
It also did not account for genetic factors, which play an important role in infertility, and did not differentiate between causes such as polycystic ovary syndrome. Other dietary factors aside from antioxidants were not measured.
Conclusions
The negative correlation between female infertility and CDAI shown by this study suggests that antioxidant intake could help prevent infertility across various groups of women.
The underlying mechanism is the counteraction of oxidative stress, which is implicated in reproductive disorders like infertility and polycystic ovary syndrome by damaging oocyte quality and endometrial receptivity, thus preserving reproductive functions.
Future studies are needed to establish causal mechanisms and account for other drivers for the development of targeted prevention and treatment strategies for female infertility.
Updated Nutri-Score system reveals stronger links between poor diet and cardiovascular disease risk