杏吧原创

Warming temperatures and more variable rainfall are reducing diet diversity among children in many countries around the world 鈥� and may even undermine efforts to improve food security.

Meredith Niles at the University of Vermont and her colleagues analysed the results of health surveys from more than 107,000 children in 19 countries 鈥� in Asia; North, south-east and West Africa; and Central and South America. The surveys were conducted between 2005 and 2009.

In the surveys, the diversity of a child鈥檚 diet was quantified with a score based on their intake of foods from different food groups, including cereal grains, dairy products and meat.

The data included details of each child鈥檚 diet the day before they were surveyed. On average, the children 鈥� aged 5 and under 鈥� consumed food from 3.2 food groups out of a possible 10. There was, however, variation from country to country. On average, children in Colombia ate 4.8 food groups and those in Lesotho just 1.8.

To study whether climate had an effect on child diet diversity, the researchers linked the results from each country to 30 years of temperature and rainfall data in the surveyed regions.

They found that higher long-term temperatures were associated with lower overall diet diversity for children everywhere except Central America.

There were shorter-term trends too. In North Africa and South America, there was typically a reduction in diet diversity in countries that experienced higher-than-average temperatures in the year prior to the survey. In Central America and West Africa, diets typically became more diverse in countries that experienced higher-than-average rainfall in the previous year.

The researchers controlled for geographic and socio-economic factors that could affect diet diversity, such as household wealth and population and livestock density. In some countries, the researchers say that the negative effect of climate on diet diversity was so great that it outweighed the beneficial impact of development efforts focused on education, improved toilet facilities and poverty reduction. The negative effects of climate may even undermine efforts to improve food security, the researchers suggest.

Diet diversity is a useful metric for regions with high rates of child malnutrition, says Daniel Mason-D鈥機roz at the Commonwealth Scientific and Industrial Research Organisation in Australia.

鈥淭hat they鈥檙e getting a fruit or a vegetable or animal product in addition to the rice or the maize [staple] 鈥� that鈥檚 an important thing to know,鈥� he says.

Mason-D鈥機roz points out that the health survey years coincided with the 2007 to 2008 world food price crisis, during which food became much more expensive. The crisis was caused by many factors and not just climate change, and may have affected diets across the world.

鈥淭here were food riots in some of the countries that were in the study,鈥� says Mason-D鈥機roz. A follow-up study with more recent data could confirm more authoritatively the effect of climate in reducing diet diversity, he says.