In the last 50 years, what's on dinner plates has grown more similar the world over – with major consequences for human nutrition and global food security, researchers said Monday.
"Diversity enhances the health and function of complex biological systems," the researchers wrote in the Proceedings of the National Academy of Sciences. But, they said, the world of food has become homogeneous, to the point of suggesting a global standard food supply.
In the last half a century, "national per capita food supplies expanded in total quantities of food calories, protein, fat and weight," they said. But at the same time, there has been "a decline in the total number of plant species upon which humans depend for food."
More people are relying on "a short list of major food crops," such as wheat, corn and soy, dairy and meat, the lead researcher, Colin Khoury, said in a news release. "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."
Khoury and his colleagues used data from the United Nations Food and Agriculture Organization to look at the composition of food supplies in 152 countries from 1961 to 2009. The total supply has increased, with animal foods becoming "increasingly important in contribution to protein and oil crops dominating fat food supplies."
That reliance on a few foods may also accelerate the rise in obesity, heart disease and diabetes, he said. And those diet-related diseases are growing even in countries with significant hunger problems.
"The literature is strong ... and it happened faster than people thought," Khoury said.
"One of the worrying issues is that as we tend toward a homogeneous diet, the regionally important crops" such as sweet potatoes, yams, sorghum, oca and maca, are declining, Khoury said by phone from the International Center for Tropical Agriculture in Cali, Colombia.
Wheat is a major staple in 97.4% of countries, and rice in 90.8%; soy is significant to 74.3% of countries, the researchers said.
The lessening of diversity of food crops also makes the food supply more vulnerable to drought, insects or disease, Khoury said, adding that that was a lesson taught by the Irish potato famine of the 1840s.
In some parts of the world, Asia and Africa in particular, the diversity of food crops has grown, as staples such as wheat and potatoes have gained importance, the researchers said. But that has meant that many minor crops that had been important have lost ground.
Factors driving the changes include rising incomes in the developing world, leading to greater consumption of animal products, moves to urban areas where fast food is plentiful, and multinational food companies marketing their products, the researchers said.
The researchers called for educating about and promoting alternative cops and supporting crop diversity and conservation.