Zinc

What was studied?

This study investigated the incidence of hypersensitivity to dental metals—specifically zinc, nickel, gold, and palladium—in patients with Irritable Bowel Syndrome (IBS). The study aimed to assess whether hypersensitivity to these metals, which are commonly used in dental prostheses, could be linked to immune activation in IBS patients. The focus was on understanding how metal-induced hypersensitivity may contribute to the low-grade mucosal inflammation observed in a subset of IBS patients.

Who was studied?

The study recruited 147 Japanese patients diagnosed with IBS according to the Rome IV diagnostic criteria and 22 healthy controls (HC). The IBS patients were classified into four subtypes:

IBS-D (diarrhea-predominant IBS): 59 patients (40.1%)
IBS-C (constipation-predominant IBS): 9 patients (6.1%)
IBS-M (IBS with mixed bowel habits): 66 patients (44.9%)
IBS-U (unspecified IBS): 13 patients (8.8%)

The subjects underwent the drug-induced lymphocyte stimulation test (DLST) to detect hypersensitivity to the metals examined quantitatively.

What were the most important findings?

Increased hypersensitivity in IBS patients: 56.5% of IBS patients demonstrated hypersensitivity to at least one metal species, compared to only 31.8% of healthy controls.

Higher sensitivity to zinc and nickel: A significant portion of IBS patients was hypersensitive to zinc (36.4%) and nickel (39.6%), whereas none of the healthy controls exhibited hypersensitivity to zinc, and only 21.1% showed sensitivity to nickel.

Severe sensitivity: IBS patients had a significantly higher stimulation index (SI) for both zinc and nickel compared to healthy controls.

No significant difference across IBS subtypes: There was no significant difference in metal hypersensitivity rates or SI values across different IBS subtypes (IBS-D, IBS-C, IBS-M, IBS-U).

What are the greatest implications of this study?

The study highlights a potential immune-mediated link between hypersensitivity to dental metals, particularly zinc and nickel, and the pathogenesis of IBS in a subset of patients. The findings suggest that metal hypersensitivity may contribute to the mucosal inflammation observed in IBS patients. This pilot study underscores the importance of considering hypersensitivity reactions as part of IBS management, potentially leading to personalized treatment approaches, such as dietary modifications like a low-nickel diet, or avoiding exposure to specific metals in dental materials.

What was studied?

This study investigated the association between dietary zinc intake and the risk of endometriosis among American women. Using cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) collected between 1999 and 2006, the researchers aimed to evaluate whether zinc intake, as a key nutritional factor, was linked to the prevalence of endometriosis. Zinc is known for its essential roles in immune modulation, antioxidative defense, and regulation of matrix metalloproteinases (MMPs), all of which are implicated in endometriosis progression.

Who was studied?

The study included 4,315 American women aged 20–54 years, of whom 331 were diagnosed with endometriosis based on self-reported doctor diagnoses. Participants’ dietary zinc intake was assessed using 24-hour dietary recall interviews, with additional data on demographics, lifestyle, and health covariates collected. Women with extreme caloric intakes or incomplete data were excluded to ensure robustness of results.

What were the most important findings?

The study revealed a positive correlation between higher dietary zinc intake and the risk of endometriosis. Women consuming over 14 mg/day of zinc had a significantly higher adjusted odds ratio (1.60, 95% CI: 1.12–2.27, p = 0.009) compared to those with intake ≤8 mg/day. Zinc’s dual role in immune modulation and antioxidative defense was emphasized, particularly its regulation of matrix metalloproteinases (MMPs) like MMP-2 and MMP-9, which are key enzymes in tissue remodeling and endometriotic lesion invasion. Interestingly, despite zinc’s known antioxidative and anti-inflammatory roles, excessive intake appeared to have a counterproductive effect. These nuanced findings highlight zinc’s complex role in endometriosis pathophysiology.

What are the greatest implications of this study?

This research underscores the potential for dietary zinc as both a marker and modifiable factor in endometriosis risk. It raises questions about zinc’s dualistic effects, where optimal levels may support immune health, but excess intake could exacerbate estrogen-related pathways in endometriosis. Clinicians should be cautious when recommending zinc supplementation for reproductive health, particularly in populations at risk for endometriosis. Furthermore, this study strengthens the biological plausibility of microbiome involvement in endometriosis, as zinc is a crucial cofactor for microbial activity, and its imbalance may alter the gut and pelvic microbiota implicated in the disease.

What was studied?

This study analyzed the relationship between zinc (Zn), copper (Cu), and the zinc-to-copper (Zn/Cu) ratio with cardiometabolic risk (CMR) factors and metabolic syndrome (MetS) using data from the Qatar Biobank. It sought to determine whether circulating levels of these trace minerals and their ratios were associated with various markers of cardiometabolic health, including lipid profiles, blood pressure, glucose levels, and body composition.

Who was studied?

The study included 437 Qatari adults aged 18 and older, representing both sexes. Participants had detailed cardiometabolic and mineral status profiles measured. Individuals with non-communicable diseases, those taking mineral supplements, and pregnant or lactating women were excluded to ensure a clear analysis of trace mineral associations with CMR factors.

Key Findings

This study revealed several associations between trace mineral levels and cardiometabolic markers. High Cu levels were associated with a reduced risk of MetS, lower diastolic blood pressure (DBP), and decreased prevalence of low HDL cholesterol, suggesting a protective role of copper in cardiometabolic health. Conversely, a higher Zn/Cu ratio was linked to an increased risk of MetS and low HDL, indicating that imbalances in these trace elements could worsen metabolic health.

While Zn alone was not strongly correlated with MetS or most CMR factors, it showed weak positive correlations with waist circumference (WC) and triglycerides (TG), which are notable for metabolic processes. Cu, on the other hand, positively correlated with HDL and total cholesterol (TC) while negatively correlating with DBP. These findings emphasize the differential and sometimes opposing roles of these minerals in cardiometabolic regulation.

In terms of microbiome relevance, trace elements like Zn and Cu influence microbial composition and metabolic functions. For example, Zn deficiency can affect glucose metabolism and inflammation, while Cu is a cofactor for antioxidative enzymes like superoxide dismutase, influencing oxidative stress pathways. Dysregulation of these pathways is often linked to microbial dysbiosis, potentially contributing to MetS and other cardiometabolic conditions.

Greatest Implications

The results underscore the need to consider trace element levels, particularly Cu and the Zn/Cu ratio, in cardiometabolic health assessments. The findings suggest that higher Cu levels confer protective effects against MetS and DBP, whereas an elevated Zn/Cu ratio increases the risk of adverse outcomes, including low HDL and MetS. These insights could inform clinical interventions, such as dietary adjustments or supplementation, to balance trace mineral levels and support cardiometabolic health. Additionally, these results highlight the potential role of trace mineral modulation as part of microbiome-targeted therapies, given their influence on systemic inflammation and metabolism.