November 23rd, 2016 / Claudia Canales, B4FA

The current food system has an intrinsic contradiction: although there are a larger number of people who are overweight than underweight, malnutrition – the “hidden hunger” – remains a pervasive problem worldwide, even among those who consume enough or too many calories. In fact, malnutrition also includes obesity and overweight. Many people do not have access to food containing adequate amounts of essential minerals, vitamins and proteins. Children, pregnant women and the elderly are particularly vulnerable and bear the brunt of the effect.

The next few blogs in this series will discuss different strategies for improving the nutritional status of target populations, starting with iodine supplementation. Although it has nothing to do with plant genetics, it highlights many of the challenges that these types of initiatives face.

The cost of malnutrition and hidden hunger is staggering, both in human and in monetary terms.

Take it with a pinch of salt

Iodine is an essential dietary element and often referred to as a micronutrient. It is required for the production of the thyroid hormones thyroxine and triiodothyronine, needed for the normal development of the brain. Iodine deficiency, in particular in children and pregnant women, can lead to severe health problems that include goitre, cretinism, neonatal hypothyroidism, growth retardation, and increase risks of pregnancy loss and infant mortality. It is estimated that 38 million babies are born each year without the protection that iodine offers the growing brain, and fully 18 million of them are mentally impaired as a result.

Iodine is found in small doses in crops, but deficiency occurs in areas where the soil has low amounts of iodine, far away from the sea and in mountainous areas. In addition, some staple foods common in iodine deficient regions, such as notably cassava and in Africa, also contain compounds that impair thyroid function, because they interfere with either the uptake of iodine or with the synthesis of thyroid hormones. This is only a problem if one of these crops provides most of the calorie intake in people’s diets. The situation is worsened by the fact that afflicted populations often also have deficiencies in other key micronutrients, such as selenium, iron and vitamin A.

At first sight delivering sufficient iodine to affected populations may seem a relatively easy task. Adding a small amount of iodine to salt (salt iodisation) is an effective prevention measure, and it is very cheap, only involving mixing simple chemicals together. Since everybody consumes salt anyway, there is no need to elicit changes in the behaviour of targeted populations. It is easy to distribute and store, taste is not noticeably changed, it is not affected by cooking and the human body absorbs it well.

Salt iodisation has been the most widely used strategy worldwide to control and eliminate health disorders associated with iodine deficiency. Yet, only three quarters of the world’s households are using iodised salt. Iodine deficiency still affects an estimated 2 billion people worldwide, mostly in Africa and Asia, and it is one of the leading causes of preventable mental retardation.

Deaths due to iodine deficiency
, per million people, 2012


Disability-adjusted life years
 (DALY) lost due to iodine deficiency, per 100 000 inhabitants, 2004

Sustain the gains

Even in countries with successful iodine fortification campaigns the long-term sustainability of initiatives can be an issue, especially if improvements are to be maintained over time. Complacency has been branded “the most dangerous enemy in the war against iodine deficiency”. Plenty of examples exist where iodine deficiency prevention programmes were discontinued once the prevention had led to iodine sufficiency, due to changes in governmental policies, or because of political change. These examples highlight the importance of stabilising iodine deficiency prevention campaigns over time.

Although the need for monitoring is compelling, very few countries have regular and systematic assessments of their iodine deficiency prevention campaigns. The simplest way to estimate iodine intake is to carry out surveys asking people about their eating habits, and then estimating total iodine consumption using national databases that indicate the iodine content of foods. Few countries, however, have adequate databases, and estimating the iodine content of animal products is difficult as it varies according to the iodine content of the feeds used.

A direct measurement of iodine intake is to measure the median urinary iodine concentration (UIC). The target UIC values of individuals with a correct iodine intake should be between 100–199 micrograms per litre. However, gold standard methods for measuring UIC levels are expensive and hence impractical for large-scale studies. Alternative methods can show good correlations, however the potential variability in results from different methods and laboratories can be large. Good training, collaboration of participating laboratories is important, as is external evaluation of the results.

Mapping iodine supply across countries presents even more challenges, since the measuring methods used are likely to be different and because other factors affecting iodine uptake are also likely to vary between countries. Monitoring should also indicate if consumed iodine levels are too high, since this also leads to health problems.

So, not at all simple

Enhancing the nutrient status of populations is difficult, especially over time, and monitoring progress is also not easy. For success, initiatives require sound policies, and long-term financial and political support.

Biofortification – increasing the level of nutrients in crops through plant breeding – presents many additional challenges. Some of these will be considered in the next blog.

Dr Claudia Canales Holzeis is a plant molecular biologist with a near-decade of experience in plant genetics research.  She previously worked as Senior Project Officer for the International Service for the Acquisition of Agri-Biotech Applications (ISAAA), based in the Philippines.  A graduate of the University of Reading in Environmental Biology, Dr.Canales gained a DPhil. in Plant Genetics at Oxford.