Rising CO2 levels may accelerate inadequate zinc intake: Research
   Date :30-Apr-2019

By Kartik Lokhande:
 
Maharashtra has experienced an above-average rate of inadequate zinc intake, which could be partly attributable to a significant shift away from a zinc-rich millet and sorghum diet, to one increasingly dominated by wheat and zinc-poor rice 
 
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 comprising 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 Climate Trends. 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,therearepoints toponder 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 relativelylittledietary change,leading to an increase from ~10 per centto 18per centininadequate intake since 1983, less than the 2011-12national average of 25per cent.“Maharashtra,however,has experienced an above-average rate of inadequate zinc intake -- 34 per cent in 2011-12, the high- estrate among the biggest states (>100 million people),” he stated in an e-mailto‘TheHitavada’. Smith stated thatthis could be partlyattributabletoa‘significant shift away’ from a zinc-rich millet and (to a lesser extent) sorghum diet,to one increasingly dominated bywheat and zincpoor 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 been able to keep up the increased demand. He predicted, “Together, these have driven upratesofdeficiencytoveryhigh levels. Furthermore, increasing CO2overthenextseveraldecades couldraisetherateofinadequate zinc intake by another 5.2 per cent, by leaching zinc from importantfoodcrops likewheat, making the condition even worse.”
 
Though the data that researchers have does not allow them to look at any more finegrained 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 the ir 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 reducedCO2 emissions couldall make a difference to slow or reverse the course.
 
Health consequences
 
ZINC plays a critical role in the immune system. Inadequate zinc intake can have serious health consequences, states the research. Particularly young children are more susceptible to contracting malaria, diarrheal diseases, and pneumonia when suffering from zinc deficiency.
 
 
‘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 power on higher cost calories fromfatsandsugarsattheexpenseofcheapercereals,”itobserves. It adds that oils consumed in India -- soybean, mustard, groundnut, coconut, ghee, and margarine -- contain ‘little zinc despite their high-caloric density’. This leaves high-income groups quite often eating less zinc compared with people who derive more of theirdietfromcereals.“Sugarsare similarlycalorie-richandnutrient-poor, further widening the gap, it states.