Pollinators in decline: Is our nutritional health at stake?

The claim that global food availability and diversity are at risk of becoming relicts of the past, once pollinator populations decline drastically, has been made multiple times throughout recent years and has never failed to co-create doomsday-like media coverage. However, this claim has been seldomly addressed empirically: a necessity in telling fact from fiction.

Fortunately, researchers from the Gund Institute for Ecological Economics at the University of Vermont, USA, were asking themselves the exact same question. By combining data on food consumption, including nutrient composition and data on pollination requirements of crop plants, they evaluated the associated nutritional health risks of different pollinator scenarios. Since pollinator-dependent effects on nutritional deficiencies may be more pronounced in developing countries, where food consumption is less flexible, their analysis set a spotlight on four countries of this category: Bangladesh, Mozambique, Uganda and Zambia. In addition, results were only presented for children aged 1-3 years old as they are likely to represent the most vulnerable group to changes in food availability and diversity.

They found out that of the nutrients examined (Vit. A, zinc, iron, folate, calcium) only Vitamin A intake depended strongly on pollinators as illustrated below (Fig 1.). Vegetables (green) and fruits (red) contributed most to the Vitamin A intake (more precisely pre-Vitamin A). The darker the respective colour, the higher the extent to which pollinators contributed to this specific food subgroup within the food group. For instance, in Uganda more than 25% of total Vitamin A intake depends heavily on vegetables which require pollination to a very high degree (95%).

Fig 1. Average proportion of dietary intake of vitamin A from different sources for children 1 to 3 years old.

Numbers in the slices of the legend indicate the percent yield due to pollinators. Darker slices are foods that depend heavily on pollinators. “Other” refers to oils, flavorings, drinks, candy, honey, and other items that do not fit into other food groups [from publication]

Next, they investigated whether a switch of scenarios from "full pollination" to "no pollinators" would result in any changes regarding the proportion of the population (1-3 y olds) which is at risk of nutritional deficiencies (Tab 1). Indeed, 0-56% of populations would be newly at risk of nutritional deficiencies - an alarming prediction. However, the underlying analysis also showed that generalizations are impossible to make. For example, in Bangladesh only a small percentage of children would become newly at risk of developing Vitamin A deficiency, but this is not because pollination is an insignificant contributor to Vitamin A intake - it is because most individuals in Bangladesh are already malnourished as the researchers state, shrinking the total numbers of newly deficient children.

Tab 1. Differences in proportion of population at risk of nutrient deficiency between the ‘no pollinators’ and ‘full pollination’ scenarios. [from publication]

Despite these obstacles to a clear-cut interpretation of the data, the investigators summarize their findings as following. Firstly, the loss of pollinators are likely to affect the nutritional health of populations which depend heavily on vegetables and fruits (in contrast to dairy and grain). Secondly, populations which are already severely malnourished or obtain nutrient intakes well above the requirements won't be disproportionately affected. Thirdly, inflexible populations regarding the inability to substitute for the loss of pollination-related foods will be at higher risk. And lastly, populations without any access to fortification or targeted nutrition programs may suffer from loss of pollinators.

Ellis AM, Myers SS, Ricketts TH (2015) Do Pollinators Contribute to Nutritional Health? PLoS ONE 10(1): e114805. doi:10.1371/journal.pone.0114805