Although bees, butterflies, and other winged creatures serve as natural pollinators for many of the world’s plants, they contribute only modestly to the world’s agricultural production—accounting for between 5% and 10% of the production of food crops. However, such natural pollinators may play a disproportionately large role in human nutrition and health, according to a new study. That's because pollinators support crops that deliver essential nutrients to malnourished regions of the world, the data show, suggesting that regions already facing food shortages and nutritional deficiencies may be especially hard hit by the global decline of bees and other pollinators.

Although pollination is essential for the cultivation of the world’s food supply, not all crops depend on pollinating animals. Corn, for example, is pollinated primarily by wind. However, many of the crops that do depend on natural pollinators are the richest in the vitamins and minerals essential for human health. Recent population declines of important pollinators, such as domesticated and wild bees, have prompted concerns for the potential effects on crop production—both economically and nutritionally. With this in mind, Rebecca Chaplin-Kramer, a landscape ecologist at Stanford University in Palo Alto, California, and colleagues set out to assess the importance of pollinators to global health by determining where pollination is most critical for the production of crops containing essential nutrients.

To do that, the team of spatial scientists, pollination biologists, and nutritionists compiled data on the nutrient content, pollination dependence, and regional agricultural yields for more than 100 of the most common crops grown globally for food. The team integrated nutritional data from the U.S. Department of Agriculture with data from previous research reports on the global production and pollination dependence of crops. Using the combined data set, the researchers then created maps to identify hotspots that are most reliant on pollinators for the production of three essential nutrients—vitamin A, iron, and folate.

Surprisingly, the researchers found that developed regions such as the United States, Europe, China, and Japan rely on natural pollinators for producing crops of high economic value, whereas parts of lesser developed regions such as India, South Asia, and sub-Saharan Africa depend more on natural pollinators for the production of crops that provide essential nutrients, as they reported last month in the Proceedings of the Royal Society B.

“Taking these three separate lines of research—where crops are grown, how nutritious are they, and how dependent are they on pollination—you realize there are really different patterns in where nutrition production is most dependent on pollination,” Chaplin-Kramer says.

The results suggest that pollinator declines could affect various regions of the world in very different ways. Ominously, the regions most dependent on pollination for providing nutrients were also those with a high prevalence of malnutrition and poverty. When the team added in data from the World Health Organization on the global distribution of vitamin A and iron deficiencies, they found that regions with a high prevalence of nutritional deficiencies overlapped with the regions most dependent on pollinators for delivering those same nutrients. Vitamin A and iron deficiencies were three times more likely to occur in areas where nutrient production was most dependent upon pollinators. Vitamin A deficiency is associated with vision loss and increased mortality, whereas iron deficiencies have been linked to pregnancy complications and impaired development and risk of death in children.

The reliance on natural pollinators is not causing the increased rates of vitamin A and iron deficiency in these less-developed regions, Chaplin-Kramer notes. "It just so happens that these places that are already really nutritionally vulnerable are also the most reliant on pollinators to deliver nutrients,” she says. Still, she adds, the “pollinators matter more in these regions, therefore if there were pollinator declines, it would hurt these regions more.”

“Whereas previous studies have identified areas at risk of losing production or income if problems with pollination arise, this study highlights that problems could be more widespread—specifically with respect to health,” says Nynke Schulp, a spatial ecologist at VU University Amsterdam, who was not involved in the study.

The link between pollinators and global nutrition adds new importance to the continuing decline of pollinator populations occurring worldwide. However, the researchers note that there are a number of ways that regions could adapt to changes in so-called pollination services—including using managed bee colonies to supplement wild pollinators, switching to nutrient-equivalent crops that are less reliant on pollination, or importing nutrient-rich foods from other regions. “This is not a doomsday scenario, it’s a call to action”, Chaplin-Kramer says. “By identifying where pollination is most critical for meeting nutritional needs, we can prioritize where to direct future research and conservation efforts.”