Some scientists say rising levels of carbon dioxide in the atmosphere may make some of our key foods less nutritious.
A team of Harvard University researchers, working in the United States, Australia and Japan, made their assessment based on experiments that simulated conditions expected by the year 2050.
They found that some staple crops, including rice, wheat, corn, and field peas had significantly lower amounts of two vital nutrients -- iron and zinc.
Shortages of these essential minerals can lead to such life-threatening diseases as malaria, pneumonia, and diarrhea.
The lack of these nutrients can also cause anemia and lower IQs in children.
As many as 3 billion people around the world receive 70 percent of iron and zinc from eating wheat, rice, and legumes.
Harvard researcher Samuel Myers says it may be possible to develop crops that are less sensitive to CO2, but only if such emissions are not increased.
The Harvard study is published in the journal Nature.