Long-term exposure to air pollution and poor lifestyle choices increase the risk of developing non-alcoholic fatty liver disease.

An unhealthy lifestyle accounts for more than 37 percent of NAFLD cases, and air pollution increases the risk, the study found.

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In a recent study published in BMC Public Health, Researchers investigated how the combined effect of lifestyle factors and ambient air pollution affects the risk of developing non-alcoholic fatty liver disease (NAFLD).

Their results suggest that while unhealthy lifestyle and long-term exposure to air pollutants significantly increase the risk of developing NAFLD, adverse lifestyle factors may influence the effect of air pollution.

Background

NAFLD may affect more than 32% of people worldwide, and this common liver disease causes other serious diseases such as hepatocellular carcinoma and cirrhosis. Cases of NAFLD are increasing, making it a public health priority.

There may be a genetic basis for the risk of NAFLD, allowing medical professionals to identify people who are more likely to develop it. However, exposure to air pollution and an unhealthy lifestyle can increase the chance of developing NAFLD.

Previous studies on this topic are limited. They have focused on East Asian populations and examined exposure to fine particles as a risk driver for NAFLD, but their findings are inconclusive. Focusing on the common link between lifestyle and air pollution can help medical professionals and policy makers design effective strategies to prevent this disease.

About the study

In this study, the researchers used data from the UK Biobank, a large, population-based study that included more than 500,000 participants aged 37-73. Participants provided information about their demographics, lifestyle, and health through questionnaires, interviews, and physical examinations.

For this analysis, subjects with liver disease, cancer, alcohol dependence, or missing data were excluded, leaving 417,025 participants.

The researchers used data from the European Study of Cohorts for the Effects of Air Pollution (ESCAPE) to assess exposure to air pollution, including various fine particles (PM2.5, PM10) and nitrogen oxides (NO2, NOx).

They also assessed lifestyle factors, including physical activity, diet, smoking, alcohol consumption, sedentary time, and sleep duration, and combined them into a lifestyle score.

The primary outcome measured was the incidence of NAFLD, which was tracked through hospital records. The analysis included statistical models to estimate the risk of NAFLD based on exposure to air pollution, lifestyle factors, and their combined effects.

Various covariates, including age, sex, socioeconomic status, and environmental factors, were adjusted to account for potential confounding variables. A sensitivity analysis was performed to ensure the robustness of the findings.

Findings

The researchers found that during a median follow-up of 12.4 years, 4,752 participants (1.14 percent) developed nonalcoholic fatty liver disease (NAFLD). The risk of NAFLD was higher in participants exposed to high levels of air pollution (eg, nitrogen dioxide, particulate matter) and those with unhealthy lifestyles.

In particular, unhealthy lifestyle factors, such as poor diet, physical inactivity, and smoking, were the main factors of NAFLD, accounting for 37.18% of the risk. Air pollution also plays a significant role in the risk of developing NAFLD, and high levels of pollution increase the likelihood of developing this disease.

The overall air pollution score (weighted average of all pollutants) showed an association of nearly 10% with NAFLD, while among air pollutants, NO2 (10.19%) and NOx (8.18%) were the most important contributors.

The study found that participants with both exposure to air pollution and unhealthy lifestyles were at the highest risk of developing NAFLD, with hazard ratios more than double compared to those with low exposure and healthy lifestyles. .

The results also showed that air pollutants and lifestyle factors interact, meaning that their combined effect on NAFLD risk is greater than the sum of their individual effects. These findings emphasize the importance of addressing environmental and lifestyle factors in the prevention of NAFLD.

conclusion

This study shows that long-term exposure to air pollutants and an unhealthy lifestyle significantly increase the risk of developing NAFLD.

Lifestyle factors, such as poor diet and physical inactivity, were the main risk factors for NAFLD. The study found that a combination of high pollution exposure and an unhealthy lifestyle led to the highest risk. These findings emphasize the importance of adopting a healthy lifestyle to reduce the impact of air pollution on liver health.

Strengths of this study include the large, population-based design and standardized assessment of air pollution exposure. However, limitations include reliance on self-reported lifestyle data, potential recall bias, and exclusion of certain cases due to missing data. In addition, the study population was predominantly of European descent, which may limit the generalizability of the findings.

Future research should examine the impact of air pollution and lifestyle factors in more diverse populations and examine the long-term effects of these risk factors on liver health.