The dual burden of malnutrition


A market in Bangalore, India. © Isabelle Aeberli, Philip Herter

How can it be that overweight people take in too many calories but at the same time too little iron? The food scientist Isabelle Aeberli has been looking for answers in the growing middle classes of Bangalore in India.

The differences between poor and rich are extreme in Bangalore. During the fourteen months of my research visit I lived in a gated apartment building with a swimming pool in the middle of it. There was even a fitness centre. But there are people there who clean the streets by hand every day for just a few dollars. Not even a technical assistant in the lab can earn nearly enough to be able to afford an apartment in a complex like mine.

"Overall, however, the wages of the Indian middle classes are growing in cities like Bangalore where the economy is flourishing. At the same time, the proportion of overweight and obese people is rising dramatically. That used to be a problem that you only encountered in countries with high living standards. Many obese people are taking in more calories than they use up, but they also often lack nutrients such as vitamins, zinc and iron. This dual burden is what interests me – how people can be overweight and yet lacking in micronutrients. It has been investigated before in the West, but what interests me is how overweight women in India are affected.

"I tackled this issue together with Anura V. Kurpad, Professor and Head of the Division of Nutrition at St. John’s Medical College and Hospital in Bangalore. We had worked together before on joint projects, so I already knew him. With the help of his team we were able to examine 150 women, mostly students or staff at the hospital.

"We indeed found that obese women display an increased risk of iron deficiency compared with women of normal weight. But this is presumably not because the food they eat contains too little iron, but because overweight people absorb it less well. Normally, the body controls exactly how much iron it absorbs because it cannot eliminate any excess, and too much of it is harmful. This control function is carried out by a protein which is produced by the liver and which puts a brake on iron absorption from the diet when there is already enough present. But in cases where the liver is chronically inflamed on account of prolonged stress or excess weight, larger amounts of this protein are produced. Obese women therefore probably absorb too little iron from their diet because their liver is producing too much of the controlling protein.

"We actually wanted to measure how much iron the women took in with their food. But regrettably this was impossible because the test subjects often underestimated their daily calorie intake, omitting things like having a cup of coffee with three sugars or the biscuits that they ate in between meals. In a second study we wanted to clarify whether a balanced diet could solve two problems at once – in other words, whether the women’s iron absorption improved when they lost weight. We hoped that a loss in weight would lower the inflammation values in the women’s blood and that their iron absorption would then function normally again. Sadly, we had to abandon this test because it again proved more complicated to carry out than we had expected.

"It took a long time to evaluate the samples, and I only received the final results after my return to Switzerland. My stay in Bangalore made me aware of how some things just don’t work in emerging and developing countries, no matter how carefully you plan them. This realisation helps me in my work at the Laboratory of Human Nutrition at ETH Zurich, where I am a Senior Scientist. Even though it sometimes required a lot of patience, I wouldn’t have wanted to miss my time in India for anything!

(From "Horizons" no. 102, September 2014)


Communication division