The impact of drinking water quality on mental health and the modifying role of diet

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In a recently published study, Dr BMC MedicineResearchers hypothesize how exposure to various trace elements in drinking water increases the risk of depression and anxiety.

Study: Association between drinking water quality and mental health and the modifying role of diet: a prospective cohort study. Image credit: New Africa/Shutterstock.com

Background

Mental health disorders, particularly depression and anxiety, are a leading cause of both disability and premature death worldwide. Following the coronavirus disease 2019 (COVID-19) pandemic, the prevalence of both anxiety and depression increased by approximately 25% worldwide, thus exemplifying the widespread prevalence of these mental disorders.

Several factors can increase a person’s risk of depression or anxiety, including genetics, social environment, and physical environment. Within the physical environment, exposure to heavy metals such as cadmium has been shown to increase the risk of depression and anxiety, while other elements such as manganese, copper and selenium, which all fight oxidative stress, are able to reduce the risk of depression. .

To date, most studies investigating the effects of environmental risk factors on the incidence of depression and anxiety have been cross-sectional. Within China, few longitudinal studies have examined how exposure to metals and nonmetals in drinking water may affect the risk of depression and anxiety.

About the study

In the current study, researchers identified individuals with depression and anxiety from Yinzhou District using International Classification of Diseases F32 and F41, respectively, in data obtained from the Yinzhou Health Information System (YHIS). Atomic absorption spectrophotometry (AAS) was used to measure the levels of manganese, zinc, copper, iron, aluminum, cadmium, selenium, and fluorine in tap water samples collected from 37 sites in Yinzhou District.

Water samples were collected four times per year, with at least one sample collected per season. Participants were assigned exposures based on their residential address and location of tap water collection points. Daily exposure to all trace elements in drinking water was calculated and adjusted based on participants’ daily drinking water intake as well as their age and gender.

A baseline survey was conducted to collect information on participants’ frequency of consumption of vegetables, meat, fruit, and fish, classifying these dietary components as low, moderate, or high. Data on sociodemographic status, lifestyle, and medical history were also obtained.

Study results

The final analysis included 24,285 individuals without a history of depression or anxiety between 2016 and 2021. From these individuals, 765 and 1,316 cases of depression and anxiety were reported, respectively, during a mean follow-up period of 4.72 and 4.68 years.

Women, as well as those who never smoked or drank, were more likely to have depression, in addition to higher risks of hypertension, dyslipidemia, cancer and stroke. Comparatively, women, less educated people, older people, never drinkers, non-smokers and those with low income were more likely to have anxiety, diabetes, dyslipidemia, cancer and stroke, in addition to lower levels of seafood and meat consumption..

Exposure to aluminum in drinking water was commonly reported in individuals with depression, whereas exposure to manganese, iron, and aluminum in drinking water was higher in individuals with anxiety. Anxious individuals were also exposed to lower levels of zinc than healthy participants.

Long-term exposure to zinc, iron, aluminum, selenium, and fluorine does not affect the risk of depression. Similarly, long-term exposure to zinc, copper, aluminum, cadmium, and fluorine did not increase the risk of anxiety.

Diet did not have a significant effect on the relationship between risk of depression and exposure to manganese, copper, and cadmium in drinking water. However, anxiety risk was higher among those who ate less fruit, more seafood and meat, and those who were exposed to manganese and iron in drinking water. Long-term exposure to copper, selenium, and fluorine was associated with an increased risk of anxiety among individuals who ate fewer vegetables and fruits.

Lower socioeconomic level was associated with increased exposure to heavy metals, particularly copper, in drinking water. Additionally, older, lower-income, and less-educated individuals exposed to cadmium in drinking water also had a higher risk of depression.

Higher levels of education were found in anxious subjects exposed to manganese and selenium in drinking water. In comparison, exposure to iron in drinking water was alarmingly more common among older and less educated individuals.

Conclusion

The findings of the current study emphasize the need to improve drinking water quality and adopt healthy dietary habits to reduce the burden of depression and anxiety, as these measures may contribute to the pathophysiology of depression and anxiety. Public health policies should also address the disproportionate impact of exposure to various trace elements in drinking water on increased risk of psychiatric disorders among people of lower socioeconomic status.

Journal Reference:

  • Zhou, S., Su, M., Shen, P. etc (2024). Association between drinking water quality and mental health and the modifying role of diet: a prospective cohort study. BMC Medicine 22(53). doi:10.1186/s12916-024-03269-3



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