The world’s largest epidemiological study of this age group (6-7-year-old children and adolescents between 13 and 14 years) has recently been published under the direction of Innes Asher and Philippa Ellwood from the University of Auckland in New Zealand. ISAAC was created in 1991 from two multinational projects in New Zealand and Germany.
“We found previously that in English-speaking countries such as Britain, New Zealand, Australia, Ireland, Canada and the U.S. asthma, hay fever and allergic skin rashes occur comparatively frequently”, says Professor of Epidemiology Ulrich Keil, founder and long-time director of the Institute of Epidemiology and Social Medicine at the Westfälische Wilhelms-University Münster. He says that there is good reason to believe that the similar eating habits in these countries play an important role. Data flows into their newly published fourth evaluation on more than 319,000 young people aged 13 to 14 years (from 51 countries) and more than 181,000 children between six and seven years (from 31 countries).
Fast food versus fruits and vegetables
Chips and Big Mac make children and adolescents therefore not only fat, but sick as well. An international group of researchers, including Ulm epidemiologists Professor Gabriele Nagel and Dr. Gudrun Weinmayr, both from the Institute of Medical Biometry and Epidemiology, University of Ulm, found that certain foods can promote the development of asthma, hay fever or allergic rashes. Consuming fruit however helps to prevent these diseases, as does consuming vegetables.
Evil trans-fats, good vegetables
The adolescents and the parents of the children were queried in the third phase of the study in 2002 and 2003 using a simple, standardised questionnaire – sometimes supplemented by videos, in which they showed the typical symptoms of asthma to respondents – including questions on the incidence and severity of asthma, hay fever and eczema as well as surveying them about their eating habits. The focus of the study was food that had been evaluated in previous study phases as asthma promoting or inhibiting, including, for example, meat, fish, fruits, vegetables, legumes, cereals, bread and pasta, rice, butter, margarine, nuts, potato, milk, eggs and fast food. In addition to insights into the diet the scientists obtained information about the sports activities of the young people and their television viewing patterns. The level of education and possible nicotine use by the mothers of the participating elementary school pupils was inquired into. The frequency of consumption was able to be specified by the responses “never or occasionally,” “once or twice a week” and “three or more times a week”.
High GDP = more asthma
At the state level, an influence was found in economic factors: The higher the gross national product (GNP) of a country, the more children and young people suffer from asthma. “The huge differences surprised us”, says Keil. “In Albania a tiny minority of respondents (<3%) reported asthma symptoms, in English speaking countries the proportion was ten times as high.” Severe asthma in rich countries is however not more widespread. The following explanation is likely close to the mark: Since medical care in rich countries is better, a worsening of symptoms can often be prevented. Germany is in all three investigated symptoms in the middle of the field. The difference between the two study centres Münster and Greifswald is relatively small, but statistically significant; in Greifswald, the surveyed children and adolescents are healthier. One possible explanation: “Nurseries were and still are on the territory of the former GDR more widespread”, says Keil. “The children are therefore more fully exposed to germs and their Immune system can thereby better develop.”
Fruit three meals per week
A negative correlation, however, formed in both age groups between fruit consumption and most symptoms: Whoever eats more fruit is healthier. Likewise at least three fruit meals per week appears to protect against the diseases mentioned. The consumption of vegetables is suggested by the study results to have a protective effect – nonetheless the relationship between vegetable consumption and positive symptoms is almost always only significant with children but not with adolescents.
“The results of this and other studies suggest close causal relationships between diet and the incidence of the diseases studied”, says Keil. “Fast food in particular seems to have a negative impact with its high proportion of trans-fats and salt, while fruit and vegetables protect through the antioxidants contained in them. Against this background, I recommend a Mediterranean diet including fish, vegetables, legumes, bread, nuts, olive and canola oil “, says the doctor. He postulates: one has to return from drug-centered medicine to the basics of healthy living – involving not only healthy eating but also sufficient physical activity and abandoning cigarette smoking.
22 year ISAAC study
The ISAAC study was launched in 1991 and translated into 50 languages. Until the current fourth study phase about two million children and young people had been interviewed and studied in 314 study centres worldwide. The questionnaires were in addition distributed to European countries and New Zealand, various nations in Central and South America and in Asia. The focus of the current phase of the study is the incidence of disease in low-income and middle-income countries. The first wave of research was primarily done in 1994 and 1995, the second on average seven years later, at the beginning of this millennium. The data collection of the current phase was completed by 2011, the analysis of the vast amounts of data, however, is still in progress. Should the findings on the relationship between fast food and asthma, hay fever and allergic skin diseases further consolidate, they would be of importance for public health systems throughout the world.