Copyright ©ERS Journals Ltd 2004 Food and fatty acid intake and atopic disease in adults1 Institute of Epidemiology, GSF National Research Center for Environment and Health, Neuherberg, Oberschleißheim, 2 Division of Metabolic Disorders and Nutrition, Kinderklinik und Kinderpoliklinik Dr von Haunersches Kinderspital, Munich, 3 Dept of Indoor Climatology, Institute of Occupational, Social and Environmalestal Medicine, Friedrich-Schiller, University Jena, Erfurt, and 4 Life Science Dept, University of Applied Sciences Albstadt-Sigmaringen, Sigmaringen, Germany CORRESPONDENCE: J. Heinrich, Institute of Epidemiology, GSF National Research Center for Environment and Health, Neuherberg, Postfach 11 29, D-85758 Oberschleißheim, Germany. Fax: 49 8931873380. E-mail: joachim.heinrich@gsf.de Keywords: atopic diseases, European Community Respiratory Health Survey, fat, margarine, monounsaturated fatty acids, polyunsaturated fatty acids
Received: June 30, 2003
This work was partly funded by German Research Association (Deutsche Forschungsgemeinschaft), research grants HEI 3294/1-1 and KO 912/8-1.
The aim of the study was to assess the relationship between dietary intake of selected foods and fatty acids with atopic disease prevalence in adults. Data from the European Community Respiratory Health Survey in Erfurt, combined with a 3-day weighed records dietary survey, was used. Complete data was available from 469 males and 333 females aged 2064 yrs. Multiple logistic regression was applied comparing the highest with the lowest quartile of dietary exposures and linear trends were tested stratified by sex. In males, margarine intake and a high ratio of omega-6 to omega-3 fatty acids were positively associated with hay fever. In females, a high intake of total fat, palmitoleic and oleic acids were positively associated with sensitisation. A high total fat, high monounsaturated fatty acid and high oleic acid consumption were positively associated with hay fever. Whilst an excessive intake of fat or imbalance in fat intake, particular of monounsaturated fatty acids, increased the risk for hay fever and allergic sensitisation in females, mostly no significant associations were found for males. Dietary factors were mostly not related with prevalence rates of bronchial hyperresponsiveness and atopic eczema either in males or in females. The prevalence of atopic disease continues to rise in industrialised countries. In the search for possible causes, attention has been focused on factors related to Western lifestyle, including dietary habits 1, 2. It was suggested that the observed increase in the consumption of polyunsaturated fatty acids (PUFA) during the 20th century, due to the wider use of fat from vegetable origin, might have contributed to the observed increase in allergy prevalence 2, 3. The supply of omega-6 fatty acids, such as linoleic acid, may increase arachidonic acid, which enhances the formation of pro-inflammatory cytokines and of immunoglobulin E (IgE) 2, 46. Available epidemiological evidence is often sex specific 79. Whether these sex differences might be related to known sex-specific dietary habits is highly speculative. Margarine may contain several-fold higher amounts of n-6 fatty acids than butter 9. Thus, in a study conducted in adult females, dietary intake of n-6 fatty acids was positively associated with hay fever 9. A European ecological study found no associations between PUFA consumption and sensitisation, but supported the hypothesis that a high intake of monounsaturated fatty acids (MUFA) may lead to the development of atopic disease 10. Epidemiological studies conducted in children revealed an inverse association between high fish consumption, which provides long chain omega-3 fatty acids, and the prevalence of asthma and bronchial hyperresponsiveness, and inferred that a decreased omega-6 to omega-3 ratio attenuates the inflammatory immune reaction 811. Evidence from a recent clinical study in neonates indicates that altered membrane PUFA profiles during gestation may influence immunological function 12. This data suggests that the amount and type of dietary fat consumed may be related to the prevalence of atopic disease. Therefore, the current study aimed to explore whether consumption of selected foods, total fat, and specific fatty acids are associated with the prevalence of atopic disease in a cross sectional study conducted on German adults.
Study design This is a cross sectional study using data from the European Community Respiratory Health Survey (ECRHS) and MONItoring of Trends and Determinants in CArdiovascular Diseases (MONICA) projects. The methods have been described in detail elsewhere and are summarised briefly for the current study 1315. The ECRHS developed a standardised protocol allowing collection of feasible data on the geographical variation of the asthma and atopic disease prevalence and their treatment in a large number of European countries. Within the framework of the MONICA Study, Erfurt data about dietary habits was collected from the study subjects. One of the objectives of this international programme conducted by the World Health Organisation was to assess the extent to which trends in coronary heart disease morbidity and mortality are related to cardiovascular risk factors, such as dietary habits 16.
Study area
Sources of data
Data collection
Study population
Dietary assessment methodology Individual daily food consumption, energy, total fat, and fatty acids were calculated from dietary records using a programme developed in the National Research Centre for Environment and Health based on the German national nutrient data file (Bundeslebensmittelschlüssel II.2) 18, 19. Although some nutrient calculations were available from previous work, all calculations were repeated with the updated nutrient data file to obtain better quality and consistent information because this data file is constantly being expanded and corrected. Therefore, the dietary data of the current study may not necessarily be identical to the published data that were derived using the preceding Bundeslebensmittelschlüssel II.1. Food intakes were presented as daily absolute amounts (g·day of consumed food1). Fatty acid intake was computed as amount of the nutrient in grams per 1000 kcal.
Outcome definition
Methacholine inhalation challenge test was performed using a Mefar MB3 dosimeter (Bovezzi, Italy) in all subjects with a forced expiratory volume >70% of the predicted mean and an absolute value of >1.5 L, who were willing to participate. Bronchial hyperresponsiveness (BHR) was defined as Presence of current hay fever as well as life-time atopic eczema was derived from the questionnaire on the basis of a positive answer about those conditions.
Statistical approach Prevalence of the outcome variables are given. Differences between sex and age groups were determined by Chi-squared test of homogeneity. Subjects were dichotomised according to the presence of allergic disease. Multiple logistic regression were used to analyse the association between food and fatty acids intake and atopic diseases. Odds ratios (OR) and their 95% confidence intervals (95% CI) were computed for the second, third, and highest intake quartiles compared to the first. Linear trends were calculated. Reported ORs were adjusted for age group, social class (defined by educational level), genetic predisposition (parental asthma or atopy), smoking habits, and body mass index.
Of the 1,281 subjects who attended the medical examination, 62.6% participated in the dietary survey. Acceptable records on food consumption were obtained from 802 subjects, 63% of whom were male (fig. 1
The prevalence of asthma, atopic sensitisation, hay fever, and atopic eczema did not differ between sexes, but the BHR rate was higher in females (table 1
Based on its low prevalence in the study sample (<5%), asthma was classified as an outcome variable (table 1
Food consumption
Fatty acids Fat consumption patterns showed no significant differences between females and males with the exception of alpha-linolenic acid, which was higher in females (table 2
Significant associations between fat intake and health outcomes were mostly limited to females, therefore, tables 69
In males, a high omega-6 to omega-3 ratio was positively related with hay fever (OR 2.81, 95% CI 1.107.16). Table 8
A high consumption of the n-3 precursor, alpha-linolenic acid, was negatively associated with atopic eczema, whereas both the linoleic to alpha-linolenic acid ratio and the total omega 6 to omega 3 ratio were significantly related to atopic eczema prevalence (table 9
This study suggests that dietary fat intake is associated with the risk for allergic sensitisation and disease manifestation, with somewhat different findings in males and females. In both males and females, there were indications for an increased risk with a high intake of omega-6 and a low intake of omega-3 fatty acids. In females, total fat and high monounsaturated fatty acids intake were also associated with an increased risk of suffering atopic manifestations. This data adds to the limited epidemiological evidence available on associations between dietary habits and atopic disease prevalence. Most of the published studies were conducted in children, and dietary intake was assessed using simple food item lists, not always well validated. Previous epidemiological studies in Germany used data on the preferred type of spreadable fats on bread as a surrogate for the type of consumed fat and without specific fatty acid determination. The authors did not consider that the total fat intake from the diet may influence the immune response 79, 20. The finding in the current study of a relation of margarine consumption to hay fever prevalence in males, is consistent with the findings from a cross-sectional study conducted in children 7. Also, results from a Japanese study support the role of PUFA intake, assessed with a food frequency protocol, in the aetiology of seasonal allergic-rhinoconjunctivitis in females. High levels of omega-6 fatty acids may alter the immune response favouring the synthesis of pro-inflammatory mediators, thus enhancing the response to allergens 2. Moreover, the ratio of omega-6 to omega-3 fatty acids, as well as the supply of the omega-6 metabolite arachidonic acid, was reported to modulate cell membrane composition, gene expression, gut permeability, as well as the activity of the lymphocytes and macrophages, and to enhance IgE production 2, 2023. In most published studies, the intake of total and omega 6 PUFA intake was inferred from margarine consumption 1, 2, 7. Depending on the conditions of its production, margarine is usually a good source of omega 6 PUFA, but often it is also rich in monounsaturated and trans-fatty acids. The potential effect of trans-fatty acids was not analysed in the current study since no reliable information on trans fatty acids was available from the German Food Composition Database. Results from a European ecological study support the hypotheses that a high monounsaturated fatty acids intake might promote the development of allergic sensitisation 10. Similar effects were found in females, such as an association of specific high IgE concentration with high monounsaturated fatty acids intake, and also with high total fat and saturated fatty acid consumption. Moreover, a positive association was found between the intake of the two major monounsaturated fatty acids, palmitoleic and oleic acids, and to allergic sensitisation. Consistently, a high fat intake, a high monounsaturated fatty acid intake, and specifically a high consumption of oleic acid were also associated with hay fever. Evidence about a positive association between high intake of oleic acid with hay fever has also been shown in a German prospective study 24. The study was unable to determinate any association between dietary fat, asthma and BHR. The low prevalence of self-reported doctor's diagnosis of asthma in the study sample impeded the application of a multiple statistical test. Additionally, the lack of significant associations between BHR and fatty acid intake may be related to the reduced number of participants on the methacholine provocation test, thus causing a loss of statistical power. Most statistically significant effects in relation to fat consumption and allergic disease in the current study were limited to females. Sex-specific dietary patterns might partly explain the observed differences. In the current study, significantly higher absolute butter and margarine intakes in males were observed, but other allergy linked dietary factors were not analysed 25. In addition, the development of atopic diseases may underlie different sex-linked physiological mechanisms. Furthermore, the lower participation rate in females may have induced bias. The authors did not consider alcohol consumption as confounder, which is markedly higher in males and might enhance oxidative stress and modulate immune responses 1619, 26. As another potential covariable, a decreased fruit and vegetable consumption with a low intake of antioxidants was suggested to be associated with recent increases in asthma 25, 27. The possible modulating role of the intestinal microflora, the dietary intake of non-digestible carbohydrates that serve as substrates for colonic bacteria, and of intestinal trophic factors has received increased attention following indications that administration of specific lactobacilli in early life may reduce the risk of atopic dermatitis 28. Thus, the effect of dietary components other than fat intake on the immune response needs to be considered in further evaluations. Given the large number of associations tested in the current study, some of the founded effects may be due to chance. However, the authors hypothesise that consistency across outcomes measurements, such as atopic sensitisation and hay fever, and independent effects observed between highly correlated fatty acids intake and atopy outcomes, reflect a valid pattern of associations. Based on the results of the current study and previously published results, the authors hypothesise that an excess of fat or imbalance in fat intake, particularly of monounsaturated fatty acids, could alter immune function and increase the risk of an allergic reaction. This data cannot demonstrate a causal association between fat consumption and atopy, in which case diet would be a modifiable risk factor and dietary manipulation might serve as a useful tool in public health programmes oriented to prevent and treat allergic disease. Prospective intervention trials would offer an opportunity to investigate these hypotheses, which hold a great potential for health prevention strategies.
The authors gratefully acknowledge A. Döring and B. Hoelscher for their helpful support and are indebted to A. Zirngibl for data management.
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