Human nutrition as a benefit of agricultural ecosystems

March 2011

The authors of a paper published in a supplement to the Food and Nutrition Bulletinin March 2011 make a case for approaching agriculture as an ecological system serving human nutrition. They argue that the same factors that enhance a farm’s ecological performance can enhance the nutritional value it produces.

Greater species diversity enhances the performance of ecological systems, the authors claim, for two reasons: as the richness of species diversity increases, the likelihood increases that at least one of the species will survive a change in the environment, and diverse species interact to facilitate each other’s success. Applying these principles to agriculture and nutrition, they introduce the concept of “functional biodiversity,” where “function” refers to the nutrients the species provides to humans, and suggests that richer functional biodiversity improves both the nutritional and ecological performance of a farm system.

To illustrate their point, they contrast two farms, each growing five species: one with functionally diverse species (maize, beans, squash, sweet potato, and guava), and one with functionally similar species (maize, rice, wheat, sorghum, and millet). Simple species biodiversity is the same for both farms (five species), but the functionally biodiverse system would supply a more diverse diet, providing a greater variety of nutrients. The functionally biodiverse system would perform better ecologically as well, since the mix of functionally dissimilar crops is more likely to have at least one survivor if growing conditions change, and because the crops facilitate each other’s success (e.g., beans fix nitrogen in the soil, benefiting the maize).

To test their concept, the authors compared hemoglobin levels in a Kenyan village based on the level of functional species biodiversity and simple species biodiversity on an individual’s farm. They found that higher functional biodiversity was associated with higher hemoglobin concentration, but detected no relationship with simple species diversity. They suggest that ecological knowledge, tools, and models have an important role to play in efforts to direct food systems at improved human nutrition.

Ecological approaches to human nutrition