New York, Aug 2 (IANS): The problem of protein deficiency is known to be widespread in India, and if carbon dioxide (CO2) levels continue to rise as projected, it may put an estimated 53 million people at new risk of consuming less than adequate dietary protein, a Harvard University study says.

The findings published online in the journal Environmental Health Perspectives, showed that human-caused carbon dioxide emissions lower the nutritional value of staple crops, increasing the risk for dietary deficiencies among the world's most vulnerable people.

The populations of 18 countries may lose more than five per cent of their dietary protein by 2050 due to a decline in the nutritional value of rice, wheat, and other staple crops, according to the study.

The researchers found that India may lose 5.3 per cent of protein from a standard diet as a result of rise in CO2 emissions.

"This study highlights the need for countries that are most at risk to actively monitor their populations' nutritional sufficiency, and, more fundamentally, the need for countries to curb human-caused CO2 emissions," said Samuel Myers of Harvard T.H. Chan School of Public Health.

The researchers estimated that roughly an additional 150 million people may be placed at risk of protein deficiency because of elevated levels of CO2 in the atmosphere.

Globally, 76 per cent of the population derives most of their daily protein from plants.

To estimate their current and future risk of protein deficiency, the researchers combined data from experiments in which crops were exposed to high concentrations of CO2 with global dietary information from the United Nations and measures of income inequality and demographics.

They found that under elevated CO2 concentrations, the protein contents of rice, wheat, barley, and potatoes decreased by 7.6 per cent, 7.8 per cent, 14.1 per cent, and 6.4 per cent, respectively.

The results suggested continuing challenges for Sub Saharan Africa, where millions already experience protein deficiency, and growing challenges for South Asian countries, including India, where rice and wheat supply a large portion of daily protein.