Food Habits Among the Arsenic-Exposed Population in the Rural Areas of Nepal and Bangladesh

Last reviewed: March 2026

Summary

This cross-sectional comparative study investigated dietary differences between arsenic-exposed populations in rural Nepal and Bangladesh and explored the potential relationship between food habits and the occurrence of arsenicosis — the clinical condition resulting from chronic arsenic toxicity. The study was conducted among 190 households from Nawalparasi district in Nepal and 200 households from Faridpur district in Bangladesh, both regions with documented arsenic contamination in groundwater.

Background

Arsenic contamination of groundwater represents one of the most significant environmental public health crises in South and Southeast Asia. The World Health Organization estimates that over 140 million people across at least 50 countries are exposed to arsenic-contaminated drinking water at concentrations exceeding the guideline value of 10 micrograms per litre. Bangladesh and the Terai region of Nepal are among the most severely affected areas, where shallow tubewells — installed in the 1970s and 1980s as a safer alternative to contaminated surface water — were subsequently found to draw water from arsenic-rich geological formations.

Chronic exposure to inorganic arsenic through drinking water leads to arsenicosis, a condition characterised initially by skin changes including melanosis (hyperpigmentation) and keratosis (thickening of the skin on palms and soles), and in more advanced cases by peripheral vascular disease, neurological impairment, and increased risk of cancers affecting the skin, bladder, lung, kidney, and liver. The latency between initial exposure and clinical manifestation of arsenicosis is typically five to fifteen years, making early detection and prevention critically important.

An intriguing epidemiological observation has driven considerable research interest: despite comparable levels of arsenic contamination in groundwater, the prevalence and severity of arsenicosis vary substantially between and within affected populations. While differences in arsenic concentration, duration of exposure, and genetic susceptibility account for some of this variation, nutritional status has emerged as an important modifying factor. Several nutrients — including protein, folate, vitamin B12, selenium, zinc, and antioxidant vitamins — have been hypothesised to modulate arsenic metabolism and toxicity through effects on arsenic methylation pathways, oxidative stress responses, and tissue repair mechanisms.

Methods

The study employed a cross-sectional comparative design. In Nepal, 190 female household heads from arsenic-affected villages in Nawalparasi district were recruited, while in Bangladesh, 200 female household heads from similarly affected villages in Faridpur district participated. Female household members were selected as respondents because they are typically responsible for food preparation and can provide reliable information about household dietary patterns.

Data were collected through structured interviews using a questionnaire that captured sociodemographic characteristics, water source and treatment practices, clinical signs of arsenicosis (verified by trained health workers), and dietary habits including staple foods, frequency of consumption of major food groups (rice, bread, vegetables, pulses, fish, meat, eggs, milk, and fruits), and methods of food preparation. The dietary assessment focused on habitual food patterns rather than precise quantitative intake, recognising the challenges of detailed dietary measurement in rural settings.

Key Results

The prevalence of arsenicosis was significantly lower among the Nepalese household members (7.3%) compared to the Bangladeshi household members (11.0%). This difference was statistically significant (χ² = 8.847; p = 0.002) and persisted after consideration of demographic factors. The majority of respondents in both countries were under 40 years of age, and the two samples were broadly comparable in terms of basic demographic characteristics.

Dietary analysis revealed substantial differences between the two populations. Nepalese households showed significantly greater consumption of bread, eggs, milk, and fruits in addition to their staple diet of rice, vegetables, and pulses. These foods are important sources of protein, B-vitamins (including folate and B12), calcium, and antioxidant vitamins — all nutrients that have been linked to improved arsenic metabolism and reduced susceptibility to arsenicosis in experimental and epidemiological studies.

Bangladeshi households, by contrast, consumed proportionally more fish and meat, but less of the dairy, egg, and fruit items that characterise the Nepalese diet. While fish and meat are valuable protein sources, the overall dietary diversity appeared to be lower among Bangladeshi households in this sample.

A particularly striking finding concerned water treatment practices. Despite the much lower prevalence of arsenicosis in Nepal, only 2.6% of Nepalese households reported using water filters to obtain arsenic-safe water, compared to 39.5% of Bangladeshi households. This counterintuitive finding strengthens the argument that nutritional factors may provide meaningful protection against arsenicosis, partially compensating for ongoing arsenic exposure through untreated water.

Discussion

The findings are consistent with the nutritional modulation hypothesis, which proposes that adequate intake of specific nutrients can modify the body’s handling of arsenic and reduce susceptibility to its toxic effects. The methylation of arsenic — the primary metabolic pathway for arsenic detoxification in humans — requires methyl donors including folate and vitamin B12, which are abundant in the eggs, milk, and vegetables consumed more frequently by the Nepalese households in this study. Antioxidant nutrients found in fruits and vegetables may also protect against arsenic-induced oxidative damage to tissues.

These findings align with intervention studies from Bangladesh and other arsenic-affected regions that have demonstrated reduced arsenicosis symptoms following nutritional supplementation, particularly with folate and antioxidant vitamins. While the present study cannot establish a direct causal link between specific nutrients and arsenicosis protection — given its observational design and the many potential confounders involved — it adds to a convergent body of evidence supporting the importance of nutrition in arsenic-affected communities.

Limitations

The cross-sectional design limits the ability to establish causality. The dietary assessment captured habitual patterns rather than quantitative nutrient intake, precluding precise analysis of nutrient-arsenicosis relationships. Arsenic concentrations in individual water sources were not measured, so the comparability of exposure levels between the two country samples cannot be confirmed. Cultural and economic differences between the two countries affect many potential confounders beyond diet alone.

Implications

The results underscore the importance of nutrition-sensitive approaches to managing arsenicosis risk in affected communities. While the provision of arsenic-safe water remains the primary prevention strategy, complementary interventions to improve dietary quality — particularly increasing consumption of protein-rich foods, dairy products, eggs, fruits, and diverse vegetables — may provide additional protection for populations that continue to face arsenic exposure. These findings have relevance not only for Nepal and Bangladesh but for all arsenic-affected regions globally where populations with marginal nutritional status face chronic arsenic exposure.