Asthma and Mediterranean diet

Asthma and Mediterranean Diet Asma e Alimentação Mediterrânica Ana Isabel Morais Duarte Orientação: Dra. Patrícia Padrão Co-orientação: Dr. Fernando Pichel Trabalho de Revisão 1.º Ciclo em Ciências da Nutrição Faculdade de Ciências da Nutrição e Alimentação da Universidade do Porto Porto, 2012 i Abstract Asthma is one of the most common chronic disease in childhood, imposing a huge burden on the patient, their family and society. There is evidence that its prevalence has increased over the last decades and is still increasing, despite there being some indications that the increase in prevalence may have plateaued in some countries in the last few years. It has been hypothesized that this increase is a consequence of changes in environmental and/or behavioral factors, namely the modification in dietary habits. A recent number of investigations agree that adherence to a Mediterranean dietary pattern can be associated with a decreased risk of current asthma symptoms. Although this evidence is promising, further research is needed. Key words: Asthma, Mediterranean diet, dietary patterns, prevalence ii Resumo A Asma é uma das doenças crónicas mais comuns na infância, acarretando consigo um enorme ónus tanto para o paciente, como para a sua família e sociedade. Há estudos que mostram que a prevalência desta patologia tem vindo a aumentar nas últimas décadas, apesar de haver algumas indicações no sentido desta estar a estabilizar em alguns países. Algumas hipóteses sugerem que este aumento é consequência de mudanças ambientais e comportamentais, nomeadamente na modificação dos hábitos alimentares. Investigações recentes assumem que a adesão ao padrão mediterrânico pode estar associada a uma diminuição dos sintomas da asma. Embora esta conclusão seja promissora, é necessária uma investigação mais aprofundada. Palavras-Chave: Asma, Dieta Mediterrânica, Padrões Alimentares, Prevalência iii Index Abstract i Key words i Resumo ii Palavras-chave ii 1. Introduction 1 2. Asthma 1 2.1. The prevalence of Asthma 1 2.2. Social and Economic Burden 3 2.3. Factors influencing the Development and Expression of Asthma 4 2.3.1. Antioxidant Hypothesis 5 2.3.2. Lipid Hypothesis 6 2.3.3. Vitamin D Hypothesis 6 3. Dietary Patterns versus Single Nutrients 7 4. Mediterranean Diet 8 5. Mediterranean Diet and Asthma 9 6. Conclusions 14 7. Acknowledgements 15 8. References 16 1 1. Introduction Asthma is a multifactorial and ordinary chronic inflammatory disorder of the airways, with a high prevalence in all age groups, but mostly in children and young adults, and it is a serious public health problem in several countries throughout the world(1-3). This review considers the current scientific evidence for the association between Mediterranean dietary and asthma. 2. Asthma Although there is no standard asthma definition, a description has been proposed by the Global Initiative for Asthma (GINA) based on the functional consequences of the airways inflammation: Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role. The chronic inflammation is associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning. These episodes are usually associated with widespread, but variable airflow obstruction within the lung and is often reversible either spontaneously or with treatment(4). 2.1. The Prevalence of Asthma The prevalence of asthma has markedly increased in the last decades, especially in children in the western world, originating what has been referred to as an 2 ‘‘allergy epidemic”(5-9). Nowadays, it is estimated that this disease affects approximately 300 million people and that is causes 250 thousand annual deaths (4, 10). It is estimated that by 2025 there could be an additional 100 million people affected by this disease(1, 11). The areas of the world's highest prevalence of asthma are in North America, Latin America and Australia (Figure 1). Nevertheless, recent evidence from epidemiological studies suggests that the prevalence of asthma reached a plateau in most industrialized countries, and may now be declining due to earlier detection and improved treatment(3, 12-14). In Europe, the prevalence of this disease ranges from 18.4% (Scotland) to 1.3% (Albania) (Table1). In particular, studies indicate that the prevalence of asthma in Portugal is 11.0% in children (6-7 years), 11.8% in adolescents (13-14 years) and 5.2% in adults (20-44 years)(15, 16). Figure 1 - Worldwide prevalence of clinical asthma(11) 3 2.2. Social and Economic Burden Asthma represents a serious economic and social impact in health care systems, on patients’ quality of life and on society as a whole(4, 12, 17, 18). In the economic analysis of asthma both direct medical costs as well as indirect non-medical costs need to be accounted for(4). On the one hand, hospital admissions and medications entail high costs for people and for health care systems(19). On the other hand, this disease is one of the most common causes of 3 Table 1 - Prevalence of Clinical Asthma in Europe (adapted from Masoli et al.)(11) Country Prevalence % Scotland 18.4 Wales 16.8 England 15.3 Republic of Ireland 14.6 Malta 8.0 Belgium 6.0 Austria 5.8 Spain 5.7 Estonia 5.4 Portugal 4.8 Italy 4.5 Poland 4.1 Denmark 3.0 Greece 1.9 Albania 1.3 10 Table 3 - Summary of studies and their findings regarding dietary factors and lung function Author Design Sample Country Main Findings De Batle et al.(13) Cross-sectional 1476 Children, 6-7 years Mexicali region, Mexico Mediterranean Diet (MD) offers a protective effect against asthma and allergic rhinitis Barros R., et al.(23) Cross-sectional 174 Adults Portugal High adherence to traditional MD increased likelihood of asthma control Chatzi et al.(47) Cross-sectional 690 Children, 7-18 years Crete, Greece Consumption of fruits, vegetables, nuts and a high adherence to a traditional MD have beneficial effects on asthma and rhinitis Gonzalez et al.(48) Cross-sectional 14700 Children and Adolescents Galicia, Spain Greater adherence to MD is associated with higher risk of severe asthma Garcia-Marcos et al.(49) Cross-sectional 20106 Children, 6-7 years Spain A Mediterranean diet has a potentially protective effect in girls aged 6-7 years Arvantini et al.(29) Cross-sectional 700 Children, 10-12 years Athens, Greece Inverse relationship between level of adherence to Mediterranean diet and prevalence of asthma Chatzi et al.(50) Review of the literature - - High level of adherence to the Mediterranean diet early in life protects against the development of asthma and atopy in children CastroRodriguez(43) Cross-sectional 1784 Children, 4 years Murcia, Spain The MD is an independent protective factor for current wheezing in pre-schoolers, irrespective of obesity and physical activity Tabak et al.(32) Cross-sectional 598 Children, 8-13 years The Netherlands High intake of whole grain products and fish may have a protective effect against asthma in children. No clear association of citrus fruit, vegetables, and dairy products intake and asthma Cook et al.(51) Cross-sectional 2650 children, 8 -11 years England Fresh fruit consumption appears to have a beneficial effect on lung function in children. Ellwood et al.(35) Cross-sectional 721 601 Children 56 different countries Negative association between vegetable consumption and asthma Farchi et al.(33) Cross-sectional 5257 Children, 6-7 years Italy High consumption of fruits and vegetables may reduce wheezing symptoms 11 control in adults(23). In rural areas of Crete, a protective effect of fruits, vegetables and nuts on self-reported wheezing in children and adolescents was observed(47). Another study in Mexican children showed that a greater adherence to a Mediterranean dietary patterns was associated with having less asthma, wheezing allergic rhinitis and current sneezing(13). In a Spanish multicentre study, Mediterranean Diet decreased the risk of severe asthma in school aged girls(49). Arvantini et al. shows that there is an inverse relationship between the level of adherence to Mediterranean diet and prevalence of asthma in school-aged children(29). Mediterranean diet has key elements that have been suggested to be responsible for the beneficial effect of diet on human health in general and potentially protective for asthma in particular. With regards to the Mediterranean diet during pregnancy and its impact on asthma, there are some recent studies suggesting that a high level of adherence to the Mediterranean diet in maternal and early life play a role in the child’s immune system development and protects against the development of asthma and atopy in children(50, 52). More specifically, consumption of vegetables more than eight times per week was inversely associated with persistent wheeze and atopy. Fish intake more than two to three times per week and legumes intake more than once per week were inversely associated with persistent wheeze. In contrast, an increased intake of red meat (more than three to four times per week) showed a trend towards positive associations with persistent wheeze and atopic wheeze in offspring (50, 52). It was also reported that olive oil (component of the Mediterranean diet), used as the main source of oil for cooking or dressing salads during pregnancy, is associated with less wheezing of the children during their first year of life(53). The main active components of olive oil include oleic acid, phenolic 12 derivatives (hydroxytyrosol, tyrosol, oleuropein, and ligstroside) and squelene, all of which have been found to exhibit a marked antioxidant activity; oleuropein and its hydrolysis product (hydroxytyrosol) being the most potent antioxidants(53). Several studies reported that a greater intake of fresh fruit and vegetables is related to a lower prevalence of respiratory symptoms(23, 51, 54, 55). In fact, these foods may provide fibre and antioxidants, which may reduce endogenous oxidative stress related to inflammatory diseases(13, 23). Furthermore, fruits and vegetables are extremely rich in vitamins C, E, ẞ-carotene, magnesium, and selenium which are associated with reduction in asthma prevalence and may prevent or limit an inflammatory response in the airways by reducing reactive oxygen species and inhibiting lipid peroxidation(29, 47, 56). In addition, flavonoids, antioxidants frequently found in fruits and red wine, may have anti-allergic and anti-inflammatory effects(28). These are associated with reduction in asthma prevalence and may prevent or limit an inflammatory response in the airways by reducing reactive oxygen species and inhibiting lipid peroxidation(29, 47). On the other hand, the Mediterranean diet encourages the consumption of nuts, including almonds, hazelnuts, walnuts, peanuts, pine nuts, pistachios and cashews, which contain a high proportion of monounsaturated (MUFA) and αlinolenic acid, fibres, vitamins (folate, vitamins E and B6), minerals (copper, magnesium, zinc and selenium) and many bioactive compounds, including a variety of polyphenols that may modulate redox status, inflammatory and immune response(23). Additionally, the relatively high consumption of fatty fish (e.g. sardine, tuna, salmon), source of n-3 fatty acids, combined with low n-6 consumption from dietary fats is typical in a Mediterranean diet. This high n-3/ n-6 fatty acid ratio 13 reduces the levels of pro-inflammatory cytokines (that are increased in asthmatic subjects) and influences the differentiation of T-helper lymphocytes(13, 54). Furthermore, long-chain n-3 PUFA decreases the production of inflammatory mediators, competitively inhibiting the metabolism of arachidonic acid (generating less active prostenoids and leukotrienes), suppressing IgE production, and thereby potentially acting to reduce airway inflammation and bronchoconstriction in asthma(27). Cereals (particularly wholegrain) are rich in vitamin D, phenolic acids, and phytic acid which are antioxidants and anti-inflammatory helping in the treatment of asthma (29, 53). Respecting religious and social beliefs, a moderate consumption of wine and other fermented beverages during meals (one glass per day for women and two glasses per day for men, as a generic reference) is recommended in this dietary pattern(45). However, the Mediterranean Diet Score considers total ethanol intake, irrespective of the different alcoholic beverages(41). On the opposite, ethanol intake was associated with increased risk of non-controlled asthma. Indeed, some studies show that alcohol consumption has been associated with hay fever symptoms, allergic sensitization and serum IgE(23, 57). Hence, the association between specific beverages and asthma needs more investigation. For all the stated reasons, high adherence to Mediterranean diet and to some of their typical components such as fresh fruits, vegetables, nuts, olive oil, and others, may have a protective role in asthma control. 14 6. Conclusions Asthma is a multifactorial disease, and there is a general consistency in the evidence that a westernized diet seems to be associated with an increased risk of incidence and prevalence of this pathology. Epidemiologic studies investigating the association between the intake of single nutrients and foods and asthma are very limited. However, dietary patterns, especially the Mediterranean, seem to have potential beneficial effects that should be taken into account. Therefore, health professionals should implement nutritional education as a means to improve healthy eating. Because asthma and allergic diseases usually have their beginnings in early life, prospective birth studies are needed to investigate the role of diet during fetal and early life. Research on potential risk factors of asthma and respiratory allergies can enhance our understanding of geographic differences and support decisions on preventive strategies. In addition, multidisciplinary studies are required to investigate the complexity of dietary factors and understand the mechanisms of this protective effect, to evaluate the most relevant window of exposure, and to address specific components of diet in relation to asthma. 15 7. Acknowledgements I would like to thank my supervisor, Dra. Patrícia Padrão, for the affection, comprehension and support throughout the research, planning and writing process of this paper. A special thanks to Dra. Renata Barros, who found the time and energy to give some guidance on her field of expertise. A huge thanks to my family, friends and boyfriend, who always supported me and gave me the strength and perseverance needed to overcome unexpected barriers. To my Sister Susana, for all the time she invested in me and for the incredible support she gave me. Thanks for being my Sister with an "S". To FCNAUP – the place where I learnt that good is not good enough; being part of this Faculty stimulates us to be the best. 16 8. References 1. Allan K, Devereux G. Diet and Asthma: Nutrition Implications from Prevention to Treatment. Journal of the American Dietetic Association. 2011; 111:258-68. 2. de Sousa JC, Santo ME, Colaço T, Almada-Lobo F, Yaphe J. Asthma in an Urban Population in Portugal: A prevalence study. BMC Public Health. 2011; 11:347. 3. Myers TR, Tomasio L. Asthma: 2015 and beyond [Review]. Respiratory care. 2011; 56(9):1389-407; discussion 407-10. 4. GINA Report, Global Strategy for Asthma Management and Prevention. 2011; available from URL: http://www.ginasthma.org/guidelines-gina-report-globalstrategy-for-asthma.html (cited 2012 Jun). 5. Torres-Borrego J, Moreno-Solís G, Molina-Terán AB. Diet for the prevention of asthma and allergies in early childhood: Much ado about something? Allergologia et Immunopathologia. 2012. 6. Kim JH, Ellwood PE, Asher MI. Diet and asthma: looking back, moving forward. Respiratory Research. 2009; 10:49. 7. Varraso R. Nutrition and Asthma. Current Allergy and Asthma Reports. 2012; 12:201-210. 8. Waltraud Eder, Ege Markus J., von Mutius Erika The Asthma Epidemic. The New England Journal of Medicine. 2006; 355:2226-35. 9. Torres-Borrego J, Molina-Terán AB, Montes-Mendoza C. Prevalence and associated factors of allergic rhinitis and atopic dermatitis in children. Allergologia et Immunopathologia. 2008; 36(2):90-100. 17 10. Fonseca MJ, Moreira, A., Moreira, P., Delgado, L., Teixeira, V., Padrão, P. Duration of Breastfeeding and the Risk of Childhood Asthma in Urban Children. Journal of Investigational Allergology and Clinical Immunology. 2010; 20(4):35758. 11. Masoli M, Fabian, D., Holt, S., & Beasley, R. . The global burden of asthma: executive summary of the GINA Dissemination Committee Report. Allergy: European Journal of Allergy and Clinical Immunology. 2004; 59: 469–478. 12. Anandan C., Nurmatov U., van Schayck O. C. P., Sheikh A. Is the prevalence of asthma declining? Systematic review of epidemiological studies. Allergy: European Journal of Allergy and Clinical Immunology. 2010; 65: 152–167. 13. de Batlle J, Garcia-Aymerich J, Barraza-Villarreal A, Anto JM, Romieu I. Mediterranean diet is associated with reduced asthma and rhinitis in Mexican children. Allergy: 1. Allan K, Devereux G. Diet and Asthma: Nutrition Implications from Prevention to Treatment. Journal of the American Dietetic Association. 2011; 111:258-68. 14. McCloud Emily, Papoutsakis Constantina. A Medical Nutrition Therapy Primer for Childhood Asthma: Current and Emerging Perspectives. American Dietetic Association. 2011; 111:1052-1064. 15. Burney P. Variations in the prevalence of respiratory symptoms, selfreported asthma attacks, and use of asthma medication in the European Community Respiratory Health Survey. European Respiratory Journal. 1996; 9, 687–695. 16. International Study of Asthma and Allergies in Chilhood. Worldwide variation in prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema: ISAAC. Lancet. 1998; 351(9111):1225-32. 18 17. von Mutius E. The burden of childhood asthma [Review]. Archives of disease in childhood. 2000; 82 Suppl 2:II2-5. 18. Nurmatov U, Devereux, G., Sheikh, A. Nutrients and foods for the primary prevention of asthma and allergy: Systematic review and meta-analysis. The Journal of Allergy and Clinical Immunology. 2011; 127(3):724-33 e1-30. 19. Braman S. The Global Burden of Asthma. Chest. 2006; 130;4S-12S. 20. Chiron R, Vachier I., Khanbabaee G., Molinari N., Varrin M., Godard P.,Chanez P. Impact of Rhinitis on Asthma Control in Children: Association With FeNO. Journal of Asthma. 2010:1–5. 21. Sennhauser FH, Braun-Fahrlander C, Wildhaber JH. The burden of asthma in children: a European perspective. Paediatric Respiratory Reviews. 2005:6: 2–7. 22. Hong S, Son DK, Lim WR, Kim SH, Kim H, Yum HY, et al. The prevalence of atopic dermatitis, asthma, and allergic rhinitis and the comorbidity of allergic diseases in children. Environmental health and toxicology. 2012; 27:e2012006. 23. Barros R, Moreira, A., Fonseca, J., de Oliveira, J. F., Delgado, L., CastelBranco M. G., Haahtela T., Lopes C., Moreira P. Adherence to the Mediterranean diet and fresh fruit intake are associated with improved asthma control. Allergy: European Journal of Allergy and Clinical Immunology. 2008; 63(7):917-23. 24. Hersoug L.-G., Linneberg A. The link between the epidemics of obesity and allergic diseases: does obesity induce decreased immune tolerance? Allergy: European Journal of Allergy and Clinical Immunology. 2007; 62: 1205–1213. 25. Devereux G. Session 1: Allergic disease: Nutrition as a potential determinant of asthma. The Proceedings of the Nutrition Society. 2010; 69(1):110. 19 26. Barros R., Moreira A., Fonseca J., Delgado L., Castelo-Branco MG., Haahtela T., et al. Dietary intake of a-linolenic acid and low ratio of n-6:n-3 PUFA are associated with decreased exhaled NO and improved asthma control. British Journal of Nutrition. 2011; 106, 441–450. 27. Arvaniti F, Priftis KN, Panagiotakos DB. Dietary habits and asthma: a review [Review]. Allergy and Asthma Proceedings : the official journal of regional and state allergy societies. 2010; 31(2):e1-10. 28. Arvaniti F, Priftis KN, Papadimitriou A, Papadopoulos M, Roma E, Kapsokefalou M, et al. Adherence to the Mediterranean type of diet is associated with lower prevalence of asthma symptoms, among 10-12 years old children: the PANACEA study. Pediatric Allergy and Immunology : official publication of the European Society of Pediatric Allergy and Immunology. 2011; 22(3):283-9. 29. Sofi F, Cesari, F., Abbate, R., Gensini, G. F., Casini, A. Adherence to Mediterranean diet and health status: meta-analysis. British Medical Journal 2008; 337:1-7. 30. Hu FB. Dietary pattern analysis: a new direction in nutritional epidemiology. Current Opinion in Lipidology. 2002; 13:3 - 9. 31. Tabak C, Wijga AH, de Meer G, Janssen NA, Brunekreef B, Smit HA. Diet and asthma in Dutch school children (ISAAC-2) [Research Support, Non-U.S. Gov't]. Thorax. 2006; 61(12):1048-53. 32. Farchi S. FF, Agabiti N., Corbo G., Pistelli R., Fortes C., Dell'Orco V., Perucci C. A. Dietary factors associated with wheezing and allergic rhinitis in children. European Respiratory Journal. 2003; 22(5):772-80. 33. Bihan H. CK, Mejean C., Peneau S., Pelabon L., Jellouli F., Le Clesiau H., Hercberg S. Sociodemographic factors and attitudes toward food affordability and