Protected areas of defined geographic zones may have unintended impacts on children’s diet

Protected areas of defined geographic zones can slow biodiversity loss and bolster conversation efforts, but they may have unintended impacts on the diets of children who live nearby, according to new research from scientists at Penn State.

Published in the British Ecological Society's journal People and Nature, the researchers analyzed children's diets in Cambodia and Myanmar by distance from the nearest protected area. They found that diet quality increased the farther from the protected area the child lived up to about 80 kilometers and then declined at greater distances. The researchers also found that, in Indigenous population areas, the odds that children ate vitamin A-rich fruits and vegetables were highest around 80 kilometers and lower both nearer and farther away. The same association did not persist in non-Indigenous areas.

Vitamin A supports growth and immune defenses in children; too little can cause night blindness and increase the risk of illness and death from infections such as measles and diarrheal disease, according to the World Health Organization. Understanding how proximity to protected areas relates to vitamin A-rich foods can help conservation and public health planners align strategies as nations expand protection goals, said Lilly Zeitler, a doctoral candidate in the Department of Geography at Penn State who led the study.

In some places, local communities rely directly on nearby lands and ecosystems for food. They manage these food systems under customary tenure - local rules enforced by tradition and social norms rather than formal laws. Creating protected areas can disrupt that customary tenure, with negative effects on how people get food. Alternatively, tourism can boost local incomes near protected areas in ways that alter households' food purchasing patterns. Despite these clear conceptual links between protected areas and local diets, these relationships remain poorly understood."

Lilly Zeitler, doctoral candidate, Department of Geography, Penn State

A large share of protected land overlaps with Indigenous territories in Cambodia and Myanmar, the researchers said, explaining that this allowed them to compare patterns across two countries with contrasting approaches to Indigenous rights.

"A cross-country comparison is interesting to see whether there are different relationships between protected areas, diets and Indigeneity in these two very different contexts," Zeitler said.

Researchers analyzed demographic and health surveys collected from rural Cambodia and Myanmar in 2014 and 2015-16, respectively, that asked caregivers of 2,899 children ages 6 to 59 months what the child ate the previous day. They matched each surveyed community to the nearest protected area and measured distance to its boundary.

The team then examined dietary diversity and whether the children ate pulses - dry, edible seeds of legumes - or vitamin A-rich fruits and vegetables across the distance gradient and by Indigenous status, adjusting for household wealth, maternal education, breastfeeding, season, market access, rainfall, elevation and proximity to water and forest cover.

The analysis showed a non-linear pattern: the highest predicted dietary diversity occurred around 80 kilometers from protected areas, where landscapes commonly mix forests and agriculture.

"For our analytic sample, mid-distances from protected areas had about a third of forest cover," Zeitler said. "One-third forest cover indicates a mix of different land uses at an 80-kilometer distance, including forest cover and agriculture, in what other researchers call an 'agroecological matrix.' These mixed landscapes appear to be associated with higher dietary diversity among young children."

They also found food-group differences by distance. In Indigenous population areas, children were most likely to eat vitamin A-rich fruits and vegetables at about 80 kilometers from protected areas, with different distance patterns for pulses. In non-Indigenous population areas, however, this association disappeared.

"We think this is because common vitamin-A rich fruits and vegetables in the region, such as mango, passionfruit, sweet potato and squash, are often grown in mixed landscapes," Zeitler said. "Mixed landscapes with swiddens and home gardens might be more important sources of vitamin-A rich fruits and vegetables for Indigenous populations in the region."

According to Zeitler, the findings offer insight for conservation planning as countries pursue the United Nations' Kunming-Montreal Global Biodiversity Framework's 30-by-30 target, a goal to conserve at least 30% of land, inland waters and oceans by 2030 with emphasis on effective management and Indigenous rights. The results point to the potential benefits of conservation approaches that recognize mixed land uses in some contexts rather than strict separation of farms and forests.

"Our results can inform conservation efforts seeking to minimize negative relationships between protected areas and local populations' health and diet quality," Zeitler said. "The results indicate that an 'agroecological matrix' approach to conservation, rather than the binary 'land sparing' model that separates people and agriculture from forests, could support local diet quality in some contexts."

Zeitler emphasized that more research is needed to fully elucidate the identified patterns of children's diet quality near protected areas.

"Because this study is based on secondary pre-existing anonymized datasets, we could not interview people in Indigenous and non-Indigenous population areas on why their consumption of some food groups differed at different distances from protected areas, for instance," Zeitler said, explaining that they could not draw causal inferences from the study, either, because the data are snapshots in time rather than tracking changes over time. The team was also unable to link country-level differences between Cambodia and Myanmar to specific policies without longitudinal data and additional analyses.

Zeitler said she hopes the findings inform conservation and health discussions as protected areas expand.

"I hope this research will stimulate debate and dialogue among conservationists and policymakers on the relationships between protected areas and local diets," Zeitler said. "The perceived need to separate forest and agriculture for conservation can be challenged by recognizing the importance of mixed land use systems for local diets, especially among Indigenous populations in some parts of the world."

Bronwen Powell, associate professor of geography, of African studies and of anthropology, co-authored the paper and serves as Zeitler's adviser. Heather Randell of the University of Minnesota's Hubert H. Humphrey School of Public Affairs also contributed to the study.