Gertrude Nabanoba preparing food for the family, Mbazzi, Mpigi district. CIFOR/Baptist Wandera

Poor diets have become a major global health concern, as people with overweight or micronutrient deficiencies have come to outnumber those who are hungry or under-nourished, according to a leading scientist.

Forests have been observed to improve the quality of diets among tropical rural populations, but until recently, there was not much evidence to show how.

As it happens, tree cover matters, but so does the size and arrangement of forest patches across landscapes, according to new findings by Canada’s University of British Columbia (UBC), the Center for International Forestry Research (CIFOR) and partner organizations.

“The diversity of peoples’ diet and their likelihood of eating fruits improves the greater the tree cover is, and the higher the number of forest patches is” says lead author Laura Vang Rasmussen from UBC’s Department of Forest and Conservation Sciences. Fruit and vegetable consumption are important indicators of varied, well-balanced diets, but people do not eat enough of them, especially in Africa.

To better understand how forests patterns affect what people eat, the authors of the research paper, including: Matthew Fagan, University of Maryland; Amy Ickowitz, CIFOR; Sylvia Wood, Canada’s Université du Québec en Outaouais; Gina Kennedy, Bioversity International; Bronwen Powell, CIFOR and Pennsylvania State University; Frédéric Baudron, International Maize and Wheat Improvement Center; Sarah Gergel, UBC; Suhyun Jung, West Virginia University; Erica Smithwick, Pennsylvania State University; Terry Sunderland, UBC and CIFOR; Stephen Wood, The Nature Conservancy and Yale School of Forestry and Environmental Studies; Jeanine Rhemtulla, UBC, selected five countries with tropical forests — Tanzania, Uganda, Nigeria, Malawi and Ethiopia — where there is geo-localized data on household food consumption. The results come from linking World Bank surveys with information on forest cover and configuration from global datasets.

BREAKING MYTHS

More blocks of forests were observed to be associated with more diverse diets in three (Uganda, Nigeria and Ethiopia) and four (Uganda, Nigeria, Ethiopia and Tanzania) of the countries, respectively.  The absence of significant associations in Malawi might be related to the fact that fruit is more widely consumed in this country, as compared to the others.

“Our next research step is to tease apart the mechanisms linking forests and diets, beyond the obvious provision of wild food,” Rasmussen said.

Despite the need for more research to explain the results, authors noted that forests patterns affect wildlife movement, pollination, seed dispersal and even people’s access to forest resources. For example, smaller patches might better support people’s diets if they tend to collect food and products along forest edges.

Tree cover also matters because forests contribute to diets in a number of ways: they provide fodder for livestock, which is a source of meat and dairy products; offer services such as pest control and nutrient recycling that can boost crop production and quality; and provide wood fuel to cook foods such as beans.

For Rasmussen, the findings also challenge the idea that people who are wealthier and better connected to markets have more diverse diets.

“We found that families in the middle wealth group were not eating more fruit than poorer households in two of the countries. Given the importance of fruit for health outcomes, this challenges the widely held assumption that promoting income-generating opportunities is enough to improve diets,” Rasmussen said.

Recognizing the role of forests in food security and nutrition matters because agricultural intensification does not necessarily lead to better diets, either. In fact, intensive agriculture may usher in monoculture cash crops, resulting in poorer diets and health.

HEALTHY LANDSCAPES AND PEOPLE

For the authors, evidence that forests influence fruit consumption calls for more research on how best to conserve forests in landscapes, taking into account regional differences.

Rasmussen will devote the next five years to further unpacking the links between forests patterns and diets, and will also study how they change over time with funding from the European Research Council. “There is still a knowledge gap on potential trade-offs between forest conservation, food production and securing high-quality diets,” she said.

She also noted that increased agricultural yields alone cannot address the widespread problem of well-balanced diets, which means there is a need to bring together the agricultural and forest sectors to advance quality diets in rural Africa and beyond.

In the paper, researchers call for a food security and nutrition strategy that maintains or increases access to forests, while diversifying agricultural production, bringing income-generating opportunities and increasing access to bio-fortifications.

“It is in everybody’s best interest to promote healthy landscapes as the basis for healthier diets for rural people,” Rasmussen said.