A recent study by Khoury et al in Proceedings of the National Academy of Sciences of the United States of America, investigated how the composition of crops contributing to human diets has changed over the past 50 years. As suspected by many, diets across the world are becoming more homogenised or more similar with greater reliance on only a handful of crops, notably wheat, rice, potatoes and sugar (energy-dense foods). Wheat is now a major food in 97% of countries. Local and traditional crops, important regionally, such as millet, rye, yams and cassava (many of which are nutrient-dense) are being produced and consumed less. Although the amount of calories, protein and fat we consume has increased over this period, the declining diversity evidenced is cause for concern. We require a variety of foods in our diet to ensure we consume adequate amounts of micronutrients, things like iron, vitamin A and iodine. Some 2 billion people in the world suffer from a lack of micronutrients in their diet, something labelled hidden hunger, which can have severe impacts on health, causing heart problems, obesity, diabetes, blindness, anaemia and goitre, and the list goes on.
An agricultural system based only on a few crops is also less resilient. If one crop fails we have only a limited number of crops to fall back on. The Irish potato famine is historical evidence for this. If this were to happen on a global scale the impacts on human lives would be unthinkable. Climate change is likely to increase the frequency and severity of events which could lead to crop failure: pest and disease outbreaks, droughts and other extreme events. Ensuring diversity in our agricultural production would be a kind of insurance against the impacts of climate change.
But what is driving this homogenisation? It could be our quest for economic efficiency: is it easier and more cost-efficient to cultivate large monocultures rather than diverse multi-crop farms? Urbanisation, rising incomes, more westernised diets, trade liberalisation, increasing trade of food, multinational food industries and food safety standardisation have all been implicated.
Authors of the paper explain we need greater cooperation between the private sector and public sector, the latter of which have the ability to pursue longer term research in crops important for health and livelihoods while the former dominate the food sector. We also need to conserve and use different crop genetic varieties, which will require public education and investment in gene and seed banks. In Norway and Sweden diets have changed little in the past 50 years as a result of campaigns to raise awareness about the impacts of food choices coupled with economic incentives such as taxation policies.
Recently, the European Parliament adopted a resolution for EU countries to implement measures to preserve crop genetic diversity in a bid to source varieties that will be able to cope with projected climatic changes. This should complement private crop breeding which focuses on only a small number of varieties. Turning the tide away from a narrowing of diets will require much investment in research, conservation and education. And an even greater effort to mobilise the private and public sectors to adopt a mandate that boosts dietary diversity.