WASHINGTON, March, 12, 2014-- A new study of global food supplies documents for the first time what its authors say has been long suspected: over the last five decades: human diets around the world have grown ever more similar ‑ by a global average of 36 percent ‑ and the trend shows no signs of slowing. And that reduction in diversity, researchers say, has major consequences for human nutrition and global food security.
“More people are consuming more calories, protein and fat, and they rely increasingly on a short list of major food crops, like wheat, [corn] and soybeans, along with meat and dairy products, for most of their food,” said lead author Colin Khoury, a scientist at the Colombia-based International Center for Tropical Agriculture (CIAT), a member of the Consultative Group on International Agricultural Research (CGIAR) Consortium. “These foods are critical for combating world hunger, but relying on a global diet of such limited diversity obligates us to bolster the nutritional quality of the major crops, as consumption of other nutritious grains and vegetables declines.”
The new study, published in the Proceedings of the National Academy of Sciences of the United States of America, suggests that growing reliance on a few food crops may also accelerate the worldwide rise in obesity, heart disease and diabetes, which are strongly affected by dietary change and have become major health problems, “even within countries still grappling with significant constraints in food availability.”
The study, which relied on data from the United Nations Food and Agriculture Organization and encompassed more than 50 crops grown in 150 countries (accounting for 98 percent of the world’s population) during the period 1961-2009, calls for urgent efforts to better inform consumers about diet-related diseases and to promote healthier, more diverse food alternatives.
Researchers say the crops now predominant in diets around the world include several that were already quite important a half-century ago, including wheat, rice, corn and potatoes. But the emerging “standard global food supply” described by the study also consists of energy-dense foods that have risen to global prominence more recently, such as soybeans, sunflower oil and palm oil. Wheat is a major staple in 97 percent of countries and rice in almost 91 percent; soybeans have become significant to 74 percent of countries.
In contrast, many crops of considerable regional importance ‑ including cereals like sorghum, millets and rye, as well as root crops such as sweet potato, cassava and yam ‑ have lost ground. Many other locally significant grain and vegetable crops ‑ for which globally comparable data are not available ‑ have suffered the same fate. For example, a nutritious tuber crop known as oca, once grown widely in the Andean highlands, has declined significantly in this region both in cultivation and consumption.
“Another danger of a more homogeneous global food basket is that it makes agriculture more vulnerable to major threats like drought, insect pests and diseases, which are likely to become worse in many parts of the world as a result of climate change,” said Luigi Guarino, a study co-author and senior scientist at the Global Crop Diversity Trust, headquartered in Germany.
As the authors probed current trends in food consumption, they documented a curious paradox: as the human diet has become less diverse at the global level over the last 50 years, many countries, particularly in Africa and Asia, have actually widened their menu of major staple crops, while changing to more globalized diets.
“In East and Southeast Asia, several major foods ‑ like wheat and potatoes ‑ have gained importance alongside longstanding staples, like rice,” Khoury noted. “But this expansion of major staple foods has come at the expense of the many diverse minor foods that used to figure importantly in people’s diets.”
The dietary changes documented in the study are driven by powerful social and economic forces. Rising incomes in developing countries, for example, have enabled more consumers to include larger quantities of animal products, oils and sugars in their diets. Moreover, urbanization in these countries has encouraged greater consumption of processed and fast foods. Related developments, including trade liberalization, improved commodity transport, multinational food industries, and food safety standardization have further reinforced these trends.
In addition to promoting the adoption of a wider range of varieties of the major crops worldwide to boost genetic diversity and reduce the vulnerability of the global food system, the researchers call for the conservation and use of plant genetic resources, including traditional varieties and wild species related to crops. They specifically urge more vigorous implementation of the International Treaty on Plant Genetic Resources for Food and Agriculture to better safeguard and share the genetic resources internationally, and increased investment in crop breeding.
The report says the nutritional quality of the major crops on which people depend must be enhanced, citing as an example crop breeding to improve the content of micronutrients like iron and zinc. And it calls for promoting alternative crops that can boost the resilience of farming and make human diets healthier through research aimed at making these crops more competitive in domestic and international markets.
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