Thursday, 8 May 2014

Could Rising Carbon Dioxide Levels Strip Foods of Some Nutrients?


Rising carbon dioxide levels could lead to declining amounts of zinc, iron, experts suggest

WebMD News from HealthDay

By Alan Mozes

HealthDay Reporter

WEDNESDAY, May 7, 2014 (HealthDay News) -- As carbon dioxide levels continue to rise around the globe, a new food investigation contends that many of the world's crops will lose vital nutrients.

The new analysis looks at how nutrients found in staple foods, such as wheat, rice, maize, sorghum, soybeans and field peas, hold up when exposed to the amount of carbon dioxide (CO2) that's expected to be in the atmosphere by the year 2050.

"The bottom-line is that our work shows that by 2050 a big chunk of the world's caloric intake will have lost a significant amount of nutrients like zinc and iron that are very important for human nutrition," said lead author Dr. Samuel Myers, a research scientist and instructor in medicine at the Harvard School of Public Health.

"Why this matters is because large vitamin and mineral deficiencies already exist today in about 2 billion people," Myers added. "And the burden of disease associated with these deficiencies is already enormous, particularly in developing countries.

"It's also the case that about 1.9 billion people now receive at least 70 percent of their dietary iron or zinc or both from staple crops like legumes and grains. So we have a major global health problem that's set to get much worse," he said.

Myers and colleagues reported their findings in a research letter published online May 7 in Nature.

Carbon dioxide is a gas that's naturally present in the atmosphere. But, it's also produced as a result of human activities, such as creating electricity and driving cars, according to the U.S. Environmental Protection Agency (EPA). The majority of CO2 now in the atmosphere comes from human activities, according to the EPA. CO2 is one of the heat-trapping gases that's contributing to climate change.

Currently, global carbon dioxide levels hover at around 400 parts per million. This compares with the roughly 280 parts per million level seen during the pre-industrial age, according to Myers.

"But most experts believe that the world will see 550 parts per million by 2050," he said.

Based on that assumption, the study team established seven agricultural sites across Australia, Japan and the United States. In turn, 41 versions of grains and legumes were planted in open-air conditions, with CO2 levels set between 546 and 586 parts per million.

Nutritional testing revealed that some crops -- such as sorghum and maize -- fared better than others, probably due to pre-existing CO2 exposure, the study authors suggested. Some forms of rice also seemed to hang on to their nutritional content despite elevated CO2 levels.

But, many varieties of rice, wheat, peas and soybeans lost significant amounts of iron and zinc. Zinc levels in wheat, for example, dropped by more than 9 percent, with iron dropping by 5 percent. Wheat also saw protein levels fall off by more than 6 percent, the investigators found.

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