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Relationship between microplastics in stool, diet, and inflammatory markers in healthy Japanese individuals
Mayumi Tsuji1, Kazue Ishitsuka2, Yasuhiro Ishihara3
1Department of Environmental Health, University of Occupational and Environmental Health, Japan.
Background:
Exposure to microplastics (MPs) can have adverse gastrointestinal effects by inducing inflammation and oxidative stress. The types of MPs in stool vary with the dietary intake. However, how MPs in the intestinal tract influence the inflammatory cytokine levels in the gastrointestinal tract in healthy individuals remains unclear, particularly in Japan, characterized by a high intake of vegetables and seafood. In this study, we investigated the relationship between food intake, stool MPs, and inflammatory markers in healthy Japanese individuals, and estimated the sources of the stool MPs.
Methods:
Twenty-two participants completed a questionnaire on daily food intake for 7 days. Thereafter, stool samples were collected to examine MP density via Fourier-transform infrared spectrophotometry. On day 8, blood samples were collected and analyzed for serum oxidative stress markers and cytokine levels. Next, the effect of total stool MP particle density (Low vs. High) on oxidative stress markers and cytokines levels was analyzed.
Results:
The median total MP particle density of the participants (median age: 44 years) was 7.20 MP particles per g of stool. Seafood intake was higher in the High MP group than in the Low MP group, with a Mann-Whitney U test yielding p = 0.035 for seafood intake. However, after the false discovery rate (FDR) correction, this effect was not significant. Nevertheless, the effect size for seafood intake was large, suggesting an association with MP level. Relative to the Low MP group, the High MP group showed significantly higher thymic stromal lymphopoietin (TSLP) levels (odds ratio: 13.5; 95% confidence interval: 0.99-183, p = 0.050). The analysis further revealed that the seafood consumed by the High MP group contained significant amounts of polyethylene (PE) and polypropylene (PP), MPs commonly used in plastic packaging (PE, p = 0.028; PP, p = 0.053).
Conclusion:
This study showed that stool MP particle density is likely associated with seafood intake and the TSLP level, implying that excessive MP intake may adversely affect human health. Therefore, measures to reduce MP exposure are urgently required.
Insights
High microplastic (MP) intake, particularly from seafood, may elevate thymic stromal lymphopoietin (TSLP) levels in healthy individuals. Reducing MP exposure is crucial for human health.
Area of Science:
- Environmental Health
- Gastroenterology
- Toxicology
Background:
- Microplastic (MP) exposure can induce gastrointestinal inflammation and oxidative stress.
- The relationship between dietary intake, MP levels in stool, and inflammatory markers in healthy individuals is not well understood, especially in Japan.
- This study investigates MP exposure, dietary habits, and inflammatory markers in healthy Japanese individuals.
Purpose of the Study:
- To investigate the association between food intake, stool MP density, and inflammatory markers in healthy Japanese individuals.
- To identify potential sources of MPs in the stool.
- To explore the impact of MP particle density on oxidative stress and cytokine levels.
Main Methods:
- A 7-day food intake questionnaire was administered to 22 participants.
- Stool samples were analyzed for MP density using Fourier-transform infrared spectrophotometry.
- Blood samples were analyzed for serum oxidative stress markers and cytokine levels, including thymic stromal lymphopoietin (TSLP).
Main Results:
- Median stool MP density was 7.20 particles/g.
- Higher seafood intake was observed in the high MP group, though not statistically significant after FDR correction.
- The high MP group exhibited significantly elevated TSLP levels (OR: 13.5, p=0.050).
- Polyethylene (PE) and polypropylene (PP) were identified as common MPs in seafood consumed by the high MP group.
Conclusions:
- Stool MP density is potentially linked to seafood consumption and elevated TSLP levels.
- Excessive MP intake may negatively impact human health.
- Urgent measures are needed to reduce MP exposure.
