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Wheat crops grown with excessive nitrogen fertiliser may increase the risk of celiac disease

According to a study published in the journal Foods, conducted under the leadership of Josep Peñuelas, CREAF and CSIC researcher, and Jordi Sardans, another CREAF researcher, with contributions from specialists in the Czech Academy of Sciences (Czech Republic), the University of Antwerp (Belgium), the Pierre Simon Laplace Institute (France), the International Institute for Applied Systems Analysis (Austria) and the Chinese Academy of Sciences in Beijing (China);  excessive use of nitrogen in the wheat fields may increase the risk of celiac disease, an autoimmune human condition

The study, titled, “Could Global Intensification of Nitrogen Fertilisation Increase Immunogenic Proteins and Favour the Spread of Coeliac Pathology?” concludes that wheat grown with excess nitrogen, transfers gliadin- a group of proteins involved in the formation of gluten- to the grains and the flour, and the allergic reaction among humans to the excess gluten, causes the coeliac disease.   

The study also confirms that the per capita intake of wheat products has remained more or less constant over the last decades, although the concentration of gliadins in wheat has increased. 

As a consequence, the average consumption of gliadins per person has increased approximately 1.5 kg more per year. Likewise, the study also confirms, that the amount of land fertilised with nitrogen, is practically the same, and what has intensified over the years, is the amount of nitrogen applied. Factors such as the new bread additives, may also cause allergies, and lead to the diagnosis of coeliac disease. 

"Nitrogen fertilisation translates into a possible direct global health problem," said Josep Peñuelas, director of the research, although he insists on the need for caution, when drawing conclusions; and reminds us that there has been very few studies on the subject. "We do not carry out the medical study, but rather warn of a new consequence. The relationship we have identified does not imply the existence of a single direct cause: there may be other factors, but this one is important.” 

He adds, “The nitrogen fertilisation that we ecologists study has very important effects on micro-organisms and the land functioning, and we add that it also has an effect on human health."  

A global health change 

The impact and harms of excessive nitrogen fertilisation has been observed mainly at the environmental scale (e.g. eutrophication and acid rain), and a direct effect on human health linked to coeliac disease is also possible. 

"Everything suggests that we have another risk factor caused by a world richer in nitrogen, through the increase in gliadins in wheat, an important risk factor that may explain, at least in part, the increase in the prevalence of coeliac disease," says Josep Peñuelas. 

The ecologist's interest in a health issue can be better understood as a global change, that is leading us to a change in global health. "As ecologists, we are dedicated to global ecology, and we are interested in working with all organisms, not only with bacteria, plants, arthropods or birds, but also with humans," he argues. 

A fertilising element and an essential grain 

The demand and application of nitrogen fertilisers in crops around the world has increased substantially. Data provided at the last International Conference of the Nitrogen Initiative indicates that global nitrogen fertiliser consumption increased by 33% between 2000 and 2013. FAOSTAT data from 2014 to 2018, indicates that frequent use of this element to improve yield of the land is common throughout the world, but with regional differences: ranging from high to low, in East Asia, South Asia, Latin America and the Caribbean, Eastern Europe and Central Asia, Sub-Saharan Africa, North America, Asia Western, North Africa and Oceania, and decreases by 1.5% in Western Europe. 

Wheat is currently the most widely planted crop and continues to be the most important food grain for humans. If on one hand, the direct consumption of foods derived from wheat has decreased in some countries (such as the US); on the other, the flour used as an additive causes a net increase in the annual per capita intake of this cereal. This means that humans have increased the net gluten consumption per person, from 4.1 kg in 1970 to 5.4 kg in 2000. The crops of this essential cereal in our diet, now occupy an area of ​​217 million hectares throughout the world.  

Eating gluten can trigger various intolerances and allergic diseases, among which celiac disease is the most widespread among humans. Its average prevalence in the general population of Europe, and the US, is approximately 1% (in the US it went from 0.2 to 1% in just 25 years). However, there are some regional differences: the prevalence of celiac disease is between 2% to 3% in Finland and Sweden, and 0.2% in Germany. 

Science is still cautious in indicating the causes, as they are largely related to the environmental components, such as the changes in the quantity and quality of ingested gluten, infant feeding patterns, spectrum of intestinal infections and colonisation by intestinal microbiota.