Dietary patterns and associations between air pollution and gestational diabetes mellitus
There is an increase in the prevalence of gestational diabetes mellitus (GDM) worldwide. Dietary patterns and air pollution are found to be closely related to the occurrence of GDM. GDM is associated with critical adverse effects on both the fetus and the mother. There is no knowledge on the interaction effect of air pollution exposure and dietary patterns on GDM. Zhang Hehua and colleagues (2021) conducted a study titled “Dietary patterns and associations between air pollution and gestational diabetes mellitus” published in Environmental International Journal. The summary of this study is given below:
Objectives:
To investigate the interaction effect between the main pre-pregnancy dietary pattern and air pollution exposure on the development of GDM.
Method:
2244 participants were part of this study. Dietary patterns were identified using factor analysis. Daily air pollution data were obtained from 78 environmental monitoring stations for PM2.5, PM10, SO2, NO2, CO, and ozone (O3) from 2017 to 2019.
Findings:
The study identified that long-term exposure to NO2, SO2, and CO prior to pregnancy was significantly associated with an increased risk of GDM. Additionally, participants with higher consumption of animal organs, animal blood, preserved eggs, and processed meat products prior to pregnancy had higher rates of GDM after exposure to air pollution. On the other hand, investigators found non-significant effects of sweet foods and traditional patterns on GDM. Inconsistent with prior researches, this study also suggests that increased exposure to PM2.5 was associated with an elevated risk of GDM. While investigators did not find a significant association between GDM and exposure to PM10, it is suggested that exposure to O3 before pregnancy decrease the risk of GDM.
Limitations:
Authors acknowledge several limitations as follows; as data were collected during pregnancy, there might exist a recall bias regarding the reporting of the pre-pregnancy diet. Secondly, there is a chance that unmeasured factors might have contributed to the observed association. Third, due to the small sample size investigators failed to identify a protective dietary pattern that could reduce the effect of exposure to air pollution on the occurrence of GDM. There might be a bias associated with the precision of air pollution exposure estimations as the study didn’t account for indoor spaces and building heights in the air pollution estimation models. Lastly, as the toxicity of PM2.5 varies greatly with different sources and composition of PM2.5, the authors acknowledge that the results regarding PM2.5 exposure and GDM in this study could be affected by the differences in toxicity of PM2.5. Authors acknowledge future studies to clarify this issue.
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