Fewer crop species are feeding the world than 50 years ago - raising concerns about the resilience of the global food system, a study has shown.
The authors warned a loss of diversity meant more people were dependent on key crops, leaving them more exposed to harvest failures.
Higher consumption of energy-dense crops could also contribute to a global rise in heart disease and diabetes, they added.
The study appears in the journal PNAS.
“Over the past 50 years, we are seeing that diets around the world are changing and they are becoming more similar - what we call the ’globalised diet’,” co-author Colin Khoury, a scientist from the Colombia-based International Center for Tropical Agriculture, explained.
Other crops provide the supplementary nutrients to diets that the major staple foods cannot deliver
"This diet is composed of big, major cops such as wheat, rice, potatoes and sugar.
“It also includes crops that were not important 50 years ago but have become very important now, particularly oil crops like soybean,” he told BBC News.
While wheat has long been a staple crop, it is now a key food in more than 97% of countries listed in UN data, the study showed.
And from relative obscurity, soybean had become “significant” in the diets of almost three-quarters of nations.
He added that while these food crops played a major role in tackling global hunger, the decline in crop diversity in the globalised diet limited the ability to supplement the energy-dense part of the diet with nutrient-rich foods.
Amid the crops recording a decline in recent decades were millets, rye, yams, sweet potatoes and cassava.