Published: Sat, May 26, 2018
Research | By Raquel Erickson

Rice to become less nutritious as Carbon dioxide levels rise

Rice to become less nutritious as Carbon dioxide levels rise

Rice within the octagon in this field is part of an experiment started by a University of Tokyo professor and created to grow rice under different atmospheric conditions.

An worldwide research team analyzed rice samples and they discovered that exposing rice to the levels of carbon dioxide that are expected in the second half of this century results in the grain containing less amount of protein, iron, and zinc, as well as lower levels of vitamins B1, B2, B5, and B9. That has the potential to severely diminish the nutritional value of rice, according to a new study published on Wednesday in Science Advances.

The researchers looked at the countries that consumed more rice - on populations that took half of their daily calories from rice.

CO2 levels in the atmosphere keep increasing, as they reached a record high in April, and since this greenhouse gas helps plants grows, its radically changing the nutrient content in food crops. "This is an underappreciated risk of burning of fossil fuels and deforestation", study co-author and director of the University of Washington Center for Health and the Global Environment Kristie Ebi said in a statement. Aside from energy-rich carbohydrates, grains feed us protein, zinc, iron and essential B vitamins. It seems that the increase of carbon dioxide levels will reduce the rice nutritional value, impacting the health and development of several millions of people. Iron, zinc and protein losses ranged from 5 percent to 20 percent.

"Vitamin B1 (thiamine) levels decreased by 17.1 per cent; average Vitamin B2 (riboflavin) by 16.6 per cent; average Vitamin B5 (pantothenic acid) by 12.7 per cent; and average Vitamin B9 (folate) by 30.3 per cent", said the report.

"Overall, these results indicate that the role of rising Carbon dioxide on reducing rice quality may represent a fundamental, but under-appreciated, human health effect associated with anthropogenic climate change".


Global warming could bring a serious problem for the two billion people on the planet who depend on one grain for their staple diet: less nutritious rice to sustain them. "Reductions in the nutritional quality of rice could affect maternal and child health for millions of people".

"For some populations in the world, rice is a major source of protein and also vitamins and also some other minerals", Professor Kobayashi said.

Some possibilities include that the Carbon dioxide takes the place of other nutrients, diminishing the need for them, or that as crops produce more grains the nutrients are in turn diluted, or the fact that Carbon dioxide causes the plant's stomates, pores in plant leaves, to close, changing the water flow and potentially affecting how water-soluble nutrients react. As carbon dioxide levels got higher, certain nutrients became less powerful.

The study's finding is disheartening, if not surprising, to researchers in the field.

The scientists suggest that either breeding or genetically engineering new strains could be a way to lessen the nutritional impact of climate change.

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