Rising CO2 levels may accelerate inadequate zinc intake: Research

Climate change, rice, and health have a connection. A new study has found that rising Carbon Dioxide (CO2) levels may accelerate inadequate zinc intake in India. For, rising CO2 levels cause many staple crops to become lower in zinc than under current atmospheric conditions. The study focussing on rice-belt of India has found that inadequate zinc intake in India could be attributable to zinc-poor rice. Obviously, inadequate zinc intake can have serious health consequences.

The study titled ‘Inadequate Zinc Intake in India: Past, Present, and Future’ has been carried out by a team of researchers comprisinng Matthew R Smith, Ruth DeFries, Ashwini Chhatre, Suparna Ghosh-Jerath, and Samuel S Myers. These researchers are from Department of Environmental Health, Harvard T H Chan School of Public Health, Boston, USA; Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, USA; Indian School of Business, Hyderabad, India; Indian Institute of Public Health, and Public Health Foundation of India. It was published recently in Food and Nutrition Bulletin. The study explores rising deficiencies of zinc intake in Indian diets, especially in rice-dominant South and North-East parts of the country.

While India has made progress at many fronts to address malnutrition, climate change impacts like rising CO2 levels can accelerate crop nutrition factors like zinc deficiency, stated Gunjan Jain of Global Strategic Communications Council (GSCC), which is a global network of communications professionals in the field of climate and energy. The study shows that national rates of inadequate zinc intake have actually been increasing from 17 per cent in 1983 to 25 per cent in 2012. This growth is equivalent to an additional 82 million people becoming deficient compared to, if, 1983 rates persisted. The highest rates of inadequate intake were concentrated mainly in Southern and North-Eastern states with rice-dominated diets -- Kerala, Tamil Nadu, Andhra Pradesh, Manipur, and Meghalaya.

However, there are points to ponder over for Madhya Pradesh (including Chhattisgarh) and Maharashtra too. According to Matthew Smith, the lead author of the study and Research Associate at Harvard T H Chan’s Department of Environmental Health, Madhya Pradesh has maintained a high average zinc intake and saw relatively little dietary change, leading to an increase from ~10 per cent to 18 per cent in inadequate intake since 1983, less than the 2011-12 national average of 25 per cent. “Maharashtra, however, has experienced an above-average rate of inadequate zinc intake -- 34 per cent in 2011-12, the highest rate among the biggest states (>100 million people),” he stated in an e-mail to ‘The Hitavada’. Smith stated that this could be partly attributable to a ‘significant shift away’ from a zinc-rich millet and (to a lesser extent) sorghum diet, to one increasingly dominated by wheat and zinc-poor rice. Millet and sorghum once comprised nearly 40 per cent of the total absorbable zinc in the diet in 1983, but the percentage has dropped to only 6 in 2011-12.

“This is the largest change of the sort for any state in India,” he added. At the same time, Smith observed, average zinc requirement of the state has increased by 7 per cent over the same time period as the population has aged, and zinc supplies have not able to keep up the increased demand. He predicted, “Together, these have driven up rates of deficiency to very high levels. Furthermore, increasing CO2 over the next several decades could raise the rate of inadequate zinc intake by another 5.2 per cent, by leaching zinc from important food crops like wheat, making the condition even worse.” Though the data that researchers have does not allow them to look at any more fine-grained within-state effects, Smith felt that if the rice-dominant states elsewhere in India were any indication, the populations that relied most heavily on rice in their diet were among ‘the worst sufferers’ of inadequate zinc intake, mainly because of low zinc content in rice. According to the researchers, national grain fortification programmes, increased dietary diversity, bio-fortified crops, and reduced CO2 emissions could all make a difference to slow or reverse the course. ‘Inadequate zinc intake rate higher in urban population’ The study points out that urban population have a ‘much higher average rate of inadequate zinc intake overall’ -- 40 per cent in 2011-12, compared to that in rural population.

The average rate of inadequate zinc intake was 18 per cent in rural population. The study attributes this discrepancy to two factors -- difference in diets between urban and rural populations, and number of older persons in urban areas (due to reduced fertility) requiring more zinc. In urban population, prevalence of inadequate zinc intake ‘actually increases with income’, infers the study. “High-income Indians, particularly in urban settings, have chosen to use their higher purchasing poweer on higher cost calories from fats and sugars at the expense of cheaper cereals,” it observes. It adds that oils consumed in India -- soybean, mustard, groundnut, coconut, ghee, and margarine -- contain ‘little zinc despite their high-caloric density’.