Periodic Reporting for period 4 - FORESTDIET (Reinterpreting how forests support people's dietary quality in low-income countries)
Okres sprawozdawczy: 2024-08-01 do 2025-07-31
In Sub-Saharan Africa, 83% of the population cannot afford a healthy diet. Consequently, 22% of the population suffers from malnutrition, which is the number one risk factor in the global burden of diseases. Inadequate intakes of fruits and vegetables is a particular problem, with an average supply of just 206 grams/person/day – much lower than the World Health Organization recommendation of 400 grams/person/day. Clearly, current agrifood systems fail to deliver nutritious and affordable fruits and vegetables.
Forests and trees hold promise as an avenue to improve local diets as they can be a source of nutrient-rich fruits and leafy vegetables. Yet, the role of forests and trees have been under-emphasized in food security policies because of the strong focus on agricultural intensification as a flagship strategy to increase calorie production. But not all calories are equal. This interdisciplinary project has examined how forests and trees are linked to people’s dietary quality in low- and middle-income countries. As the debate around how best to feed the world in a sustainable manner grows, pursuing an in-depth understanding of how forests and trees support dietary quality is paramount to overcome nutrient deficiencies. This is especially true for many low-and middle-income countries facing high deforestation rates due to foreign interests in commercial agriculture - in addition to the challenge of high nutrient deficiency rates.
Over the course of FORESTDIET, we have found solid evidence that forests and trees play a key role for local people's dietary quality. We have observed this both through broad-scale analyses and detailed local level studies. For example, using data from more than 15,000 households from 10 African countries, we found that even low levels of tree cover improve people’s dietary quality. In Tanzania, we estimated the impacts of deforestation on people’s food intake. We found that deforestation caused a reduction in fruit and vegetables consumption of 14g per day per person, which represents 11% of average daily intake. In Malawi, we found that sourcing food from on-farm trees is associated with increased micronutrient adequacy for women, including vitamin A, iron, folate, and zinc.
Taken together, these studies robustly evidence the benefits of forests and trees to people’s nutrition.
Forests and trees hold promise as an avenue to improve local diets as they can be a source of nutrient-rich fruits and leafy vegetables. Yet, the role of forests and trees have been under-emphasized in food security policies because of the strong focus on agricultural intensification as a flagship strategy to increase calorie production. But not all calories are equal. This interdisciplinary project has examined how forests and trees are linked to people’s dietary quality in low- and middle-income countries. As the debate around how best to feed the world in a sustainable manner grows, pursuing an in-depth understanding of how forests and trees support dietary quality is paramount to overcome nutrient deficiencies. This is especially true for many low-and middle-income countries facing high deforestation rates due to foreign interests in commercial agriculture - in addition to the challenge of high nutrient deficiency rates.
Over the course of FORESTDIET, we have found solid evidence that forests and trees play a key role for local people's dietary quality. We have observed this both through broad-scale analyses and detailed local level studies. For example, using data from more than 15,000 households from 10 African countries, we found that even low levels of tree cover improve people’s dietary quality. In Tanzania, we estimated the impacts of deforestation on people’s food intake. We found that deforestation caused a reduction in fruit and vegetables consumption of 14g per day per person, which represents 11% of average daily intake. In Malawi, we found that sourcing food from on-farm trees is associated with increased micronutrient adequacy for women, including vitamin A, iron, folate, and zinc.
Taken together, these studies robustly evidence the benefits of forests and trees to people’s nutrition.
Over the course of the project, we have provided solid evidence on how forests and trees affect people’s diet in Africa. We have adopted an innovative multi-scale research design to provide both broad scale evidence and detailed local level insight.
At the broad scale, we found that even low levels of tree cover improve people’s dietary quality in West Africa. Specifically, we find that the probability of consuming vitamin A–rich foods increases with an increase in tree cover. These findings were based on data from more than 15,000 households across 10 West African countries.
Also at the broad scale, we found that tree plantations and forest regrowth are linked to poverty reduction across 18 African countries. By combining a recent map that distinguishes tree plantations from regrowth from 2000 to 2012 with multidimensional poverty measures from more than 200,000 households, we found a positive association between people's living standards and areas where tree plantations have expanded or, to a lesser extent, forest regrowth has occurred.
We also combined the new map on forest regrowth with food consumption panel data from Nigeria from 1100 households. We found that people living in areas where forest regrowth has occurred have a higher intake of fruits and vegetables and thus higher dietary diversity.
Using panel data from Tanzania, we were able to estimate how deforestation affects people’s dietary quality. We found that deforestation caused a reduction in fruit and vegetables consumption of 14g per day per person, which represents 11% of average daily intake. We also conducted a detailed longitudinal study in Tanzania to explore how changes in food environments have shaped the acquisition and consumption of wild foods among people living near forests. We used data collected in both the dry and rainy seasons in 2009 and 2021/2022. We found that the proportion of people who collected wild foods within the past seven days had declined from 90 to 61% in the dry season and from 99 to 72% in the wet season. The main reasons were 1) decreased availability caused by, for example, loss of biodiversity, 2) lack of access due to government forest regulations, and 3) increased desirability towards marked-based foods .
Analogously, we used panel data from Malawi to examine the effects of trees on farms on people's dietary quality. We found that having on-farm trees leads to higher and more diverse fruit and vegetable consumption. Specifically, households who had trees on their farm exhibited a 3% increase in vegetable consumption compared to households without trees. Moreover, for every additional tree species owned or acquired by a household during the study period, fruit consumption increased by 5%. In Malawi, we also linked detailed survey data from 460 households to high-resolution tree-cover data. We found that women from households that source food from on-farm trees have higher levels of zinc, vitamin A, iron and folate adequacy compared with women from households that do not source food from on-farm trees. For example, women sourcing food from trees on their farms have on average 8–15% higher folate adequacy, depending on the season.
At the broad scale, we found that even low levels of tree cover improve people’s dietary quality in West Africa. Specifically, we find that the probability of consuming vitamin A–rich foods increases with an increase in tree cover. These findings were based on data from more than 15,000 households across 10 West African countries.
Also at the broad scale, we found that tree plantations and forest regrowth are linked to poverty reduction across 18 African countries. By combining a recent map that distinguishes tree plantations from regrowth from 2000 to 2012 with multidimensional poverty measures from more than 200,000 households, we found a positive association between people's living standards and areas where tree plantations have expanded or, to a lesser extent, forest regrowth has occurred.
We also combined the new map on forest regrowth with food consumption panel data from Nigeria from 1100 households. We found that people living in areas where forest regrowth has occurred have a higher intake of fruits and vegetables and thus higher dietary diversity.
Using panel data from Tanzania, we were able to estimate how deforestation affects people’s dietary quality. We found that deforestation caused a reduction in fruit and vegetables consumption of 14g per day per person, which represents 11% of average daily intake. We also conducted a detailed longitudinal study in Tanzania to explore how changes in food environments have shaped the acquisition and consumption of wild foods among people living near forests. We used data collected in both the dry and rainy seasons in 2009 and 2021/2022. We found that the proportion of people who collected wild foods within the past seven days had declined from 90 to 61% in the dry season and from 99 to 72% in the wet season. The main reasons were 1) decreased availability caused by, for example, loss of biodiversity, 2) lack of access due to government forest regulations, and 3) increased desirability towards marked-based foods .
Analogously, we used panel data from Malawi to examine the effects of trees on farms on people's dietary quality. We found that having on-farm trees leads to higher and more diverse fruit and vegetable consumption. Specifically, households who had trees on their farm exhibited a 3% increase in vegetable consumption compared to households without trees. Moreover, for every additional tree species owned or acquired by a household during the study period, fruit consumption increased by 5%. In Malawi, we also linked detailed survey data from 460 households to high-resolution tree-cover data. We found that women from households that source food from on-farm trees have higher levels of zinc, vitamin A, iron and folate adequacy compared with women from households that do not source food from on-farm trees. For example, women sourcing food from trees on their farms have on average 8–15% higher folate adequacy, depending on the season.
Our work presents a significant advancement of the current state of the art as we have provide detailed estimates of how forests and trees affect people’s diets - across scales and contexts. Specifically, we have moved beyond simple dietary diversity metrics and have provided exact estimates of how forests and trees contribute to people’s micronutrient adequacy levels. Also, we have been able to move beyond point-in-time studies and instead show how both forest loss and regrowth affect people’s diets.
While increased agricultural production of cereals will undoubtedly be important for meeting the food needs of a growing population, our findings should push policymakers to think beyond cereals and calories when trying to improve food security and nutrition in rural communities. As such, our findings lay the ground for transforming our understanding of landscape-diet linkages. Given the speed and magnitude of forest loss across the world, such advancements in knowledge are critical to ensure that food and nutrition security strategies move beyond agricultural production and yields to embrace the key nutritional problem of nutrient deficiencies and the role that forests and trees can play to alleviate them.
While increased agricultural production of cereals will undoubtedly be important for meeting the food needs of a growing population, our findings should push policymakers to think beyond cereals and calories when trying to improve food security and nutrition in rural communities. As such, our findings lay the ground for transforming our understanding of landscape-diet linkages. Given the speed and magnitude of forest loss across the world, such advancements in knowledge are critical to ensure that food and nutrition security strategies move beyond agricultural production and yields to embrace the key nutritional problem of nutrient deficiencies and the role that forests and trees can play to alleviate them.