Higher dietary zinc linked to increased endometriosis risk in US study

Women with higher dietary zinc levels are more likely to develop endometriosis, a chronic inflammatory condition affecting an estimated 176 million worldwide, according to a recent study.

Published in BMC Public Health, the study used data from the National Health and Nutrition Examination Survey and found a link between the essential mineral and ureteral disease in US women. The researchers surveyed 4,315 women aged 20 to 54 between 1999 and 2006.

The study explains that endometriosis causes tissue resembling endometrial tissue to grow outside the uterus on organs and tissues within the pelvic region, causing pain and infertility.

Despite being a public health issue, little is known about the “modifiable risk” factors that can prevent endometriosis.

The paper details: “Endometriosis is 40–60% more common in women with dysmenorrhea, 21–47% more common in women with subfertility and 71–87% more common in women with pelvic pain. Notably, women with endometriosis incur healthcare costs more than twice as high as those without the condition.”

Modifiable factors found

Researchers conducted the evaluation using a multivariable logistic regression model, adjusting for age, lifestyle factors and other factors. 

Higher dietary zinc intake correlates with endometriosis, especially in women consuming over 14 mg of zinc daily.They confirmed that women taking higher levels of dietary zinc had an increased risk for endometriosis — suggesting modifiable factors may affect the condition.

The researchers state: “Relative to those with lower zinc intake (8 mg or less daily), women consuming moderate zinc levels (8–14 mg daily) exhibited a 19% increase in endometriosis risk. Those consuming over 14 mg per day showed a 60% higher risk.” 

Although the results for the 8–14 mg/day group were not statistically significant, those for those who consumed more than 14 mg/day were, indicating a clearer link at higher consumption levels.

However, even after controlling for possible confounding variables, the study’s cross-sectional design makes proving a direct link between zinc consumption and endometriosis impossible.

Balancing zinc levels

Researchers cite studies that have linked zinc’s importance to immune function and reproductive health. 

Endometriosis is characterized by immune dysregulation and oxidative stress, which led scientists to study zinc, an antioxidant, immune regulator and anti-inflammatory agent. The study details that since zinc cannot be stored in the body, it is important to maintain adequate levels through diet.

While zinc’s effects on the male reproductive system are relatively well studied, data on its impact on female reproductive health remain limited, according to the paper.

Zinc may impact tissue remodeling in endometriosis by controlling matrix metalloproteinases (MMPs), enzymes that break down cells. Elevated MMP activity, particularly of MMP-2 and MMP-9, has been observed in endometriotic lesions, suggesting that zinc’s regulatory role on the enzymes may impact the progression of endometriosis. 

The researchers call for future studies to confirm their findings and to explore the potential threshold effects of zinc on endometriosis risk. 

At last week’s SupplySide West trade show, companies showcased a range of women’s health supplements, from vaginal health and menopause management to beauty-from-within supplements. On the show floor, Nutrition Insight discussed women’s health products presented by Gnosis by Lesaffre, IFF and Kerry.