Novo estudo sugere que ingestão de frutas e vegetais tem impacto limitado no câncer

Resultado da pesquisa europeia enfraquece recomendação da OMS para prevenção da doença

A ingestão de mais frutas e hortaliças, recomendada pela Organização Mundial da Saúde (OMS), tem um impacto muito limitado na luta contra o câncer, segundo um novo estudo [Fruit and Vegetable Intake and Overall Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC)] do qual participaram 500 mil europeus.

Uma equipe internacional de médicos, dirigida pela Mount Sinai School of Medicine de Nova York, calculou que só poderiam ser evitados cerca de 2,5% dos casos de câncer com uma dieta que recomenda o consumo de pelo menos cinco frutas ao dia. Reportagem da Agência EFE, com informações complementares do EcoDebate.

O novo estudo, publicado no Journal of the National Cancer Institute, dos EUA, que analisou voluntários de cinco países, indica que a associação entre a ingestão de mais verduras e frutas e a prevenção do câncer é muito fraca.

Seus autores dizem não poder descartar que inclusive a pequena redução observada dos casos de câncer entre os que seguem essa dieta se deva ao fato de esses indivíduos levarem um tipo de vida mais saudável também em outros aspectos.

No melhor dos casos, assinalam os especialistas, o consumo de duas porções extras de fruta e hortaliças por dia pode prevenir 2,6% dos tipos de câncer nos homens e 2,3% nas mulheres.

As hortaliças, mais ricas em nutrientes, parecem ter efeitos mais benéficos que a fruta, e as pessoas que fazem uso de bebidas alcoólicas e fumantes, que estão mais expostas ao câncer que as que levam um tipo de vida mais saudável, são as que mais podem se beneficiar dessa dieta.

Apesar de o vínculo entre a dieta e o câncer não estar totalmente clara, a obesidade é considerada um fator certo de risco, e desse ponto de vista, uma dieta mais vegetariana pode ter efeitos positivos.

Apesar de tudo, a doutora Rachel Thompson, do World Câncer Research Fund, citada pela BBC, considera que uma redução de 2,5% dos casos de câncer no mundo é significativa, por isso diz que convém seguir recomendando esse tipo de dieta.

O artigo “Fruit and Vegetable Intake and Overall Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC)” apenas está disponível para assinantes da revista Journal of the National Cancer Institute. Para maiores informações transcrevemos, abaixo, o abstract.

Fruit and Vegetable Intake and Overall Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC)
Paolo Boffetta, Elisabeth Couto, Janine Wichmann, Pietro Ferrari, Dimitrios Trichopoulos, H. Bas Bueno-de-Mesquita, Fränzel J. B. van Duijnhoven, Frederike L. Büchner, Tim Key, Heiner Boeing, Ute Nöthlings, Jakob Linseisen, Carlos A. Gonzalez, Kim Overvad, Michael R. S. Nielsen, Anne Tjønneland, Anja Olsen, Françoise Clavel-Chapelon, Marie-Christine Boutron-Ruault, Sophie Morois, Pagona Lagiou, Androniki Naska, Vassiliki Benetou, Rudolf Kaaks, Sabine Rohrmann, Salvatore Panico, Sabina Sieri, Paolo Vineis, Domenico Palli, Carla H. van Gils, Petra H. Peeters, Eiliv Lund, Magritt Brustad, Dagrun Engeset, José María Huerta, Laudina Rodríguez, Maria-José Sánchez, Miren Dorronsoro, Aurelio Barricarte, Göran Hallmans, Ingegerd Johansson, Jonas Manjer, Emily Sonestedt, Naomi E. Allen, Sheila Bingham, Kay-Tee Khaw, Nadia Slimani, Mazda Jenab, Traci Mouw, Teresa Norat, Elio Riboli, Antonia Trichopoulou

Affiliations of authors: Lifestyle and Cancer Group, International Agency for Research on Cancer, Lyon, France (PB, EC, NS, MJ); Section of Environmental Health, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark (JW); School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa (JW); Data Collection and Exposure Unit, European Food Safety Authority, Parma, Italy (PF); Department of Hygiene and Epidemiology, University of Athens Medical School, Athens, Greece (DT, PL, AN, VB, ATr); Centre for Nutrition and Health, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands (H-BB-d-M, FJBvD, FLB); Julius Center for Health Sciences and Primary Care, University Medical Center, Utrecht, the Netherlands (FJBvD, CHvG, PHP); Department of Epidemiology, Biostatistics and HTA, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands (FLB); Cancer Epidemiology Unit, University of Oxford, Oxford, UK (TK, NEA); Department of Epidemiology, German Institute of Human Nutrition, Potsdam-Rehbrücke, Germany (HB, UN); Division of Cancer Epidemiology, German Cancer Research Center, Heidelberg, Germany (JL, RK, SR); Unit of Nutrition, Environment and Cancer, Cancer Epidemiology Research Programme, Catalan Institute of Oncology, The Bellvitge Institute for Biomedical Research (IDIBELL), Barcelona, Spain (CAG); Department of Clinical Epidemiology (KO) and Department of Cardiology (MRSN), Aarhus University Hospital, Aalborg, Denmark; Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark (ATj, AO); INSERM, ERI20, EA 4045, Institut Gustave-Roussy, Villejuif, France (FC-C, M-CB-R, SM); Department of Clinical and Experimental Medicine, Federico II University, Naples, Italy (SP); Department of Preventive and Predictive Medicine, Nutritional Epidemiology Unit, Fondazione IRCSS Istituto Nazionale dei Tumori, Milan, Italy (SS); Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK (PV, TM, TN, ER); Institute for Scientific Interchange Foundation, Torino, Italy (PV); Molecular and Nutritional Epidemiology Unit, Cancer Research and Prevention Institute, Florence, Italy (DP); Department of Community Medicine, University of Tromsø, Tromsø, Norway (EL, MB, DE); Department of Epidemiology, Murcia Regional Health Council, Murcia, Spain (JMH); CIBER Epidemiología y Salud Pública (CIBERESP), Murcia, Spain (JMH); Public Health and Participation Directorate, Health and Health Care Services Council, Asturias, Spain (LR); Andalusian School of Public Health, Granada, Spain (M-JS); CIBER de Epidemiología y Salud Pública (CIBERESP), Granada, Spain (M-JS); Public Health Division of Gipuzkoa, Basque Government (MD); CIBER de Epidemiología y Salud Pública (CIBERESP), San Sebastian, Spain (MD); Instituto de Salud Pública, Pamplona, Spain (AB); Department of Public Health and Clinical Medicine (GH) and Department of Odontology (IJ), Umeå University, Umeå, Sweden; Department of Surgery, Malmö University Hospital, Malmö, Sweden (JM); Department of Clinical Sciences in Malmö/Nutrition Epidemiology, Lund University, Malmö, Sweden (ES); Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK (SB, K-TK)

Correspondence to: Paolo Boffetta, MD, MPH, The Tisch Cancer Institute, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029 (e-mail: paolo.boffetta{at}mssm.edu).

Background: It is widely believed that cancer can be prevented by high intake of fruits and vegetables. However, inconsistent results from many studies have not been able to conclusively establish an inverse association between fruit and vegetable intake and overall cancer risk.

Methods: We conducted a prospective analysis of the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort to assess relationships between intake of total fruits, total vegetables, and total fruits and vegetables combined and cancer risk during 1992–2000. Detailed information on the dietary habit and lifestyle variables of the cohort was obtained. Cancer incidence and mortality data were ascertained, and hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariable Cox regression models. Analyses were also conducted for cancers associated with tobacco and alcohol after stratification for tobacco smoking and alcohol drinking.

Results: Of the initial 142 605 men and 335 873 women included in the study, 9604 men and 21 000 women were identified with cancer after a median follow-up of 8.7 years. The crude cancer incidence rates were 7.9 per 1000 person-years in men and 7.1 per 1000 person-years in women. Associations between reduced cancer risk and increased intake of total fruits and vegetables combined and total vegetables for the entire cohort were similar (200 g/d increased intake of fruits and vegetables combined, HR = 0.97, 95% CI = 0.96 to 0.99; 100 g/d increased intake of total vegetables, HR = 0.98, 95% CI = 0.97 to 0.99); intake of fruits showed a weaker inverse association (100 g/d increased intake of total fruits, HR = 0.99, 95% CI = 0.98 to 1.00). The reduced risk of cancer associated with high vegetable intake was restricted to women (HR = 0.98, 95% CI = 0.97 to 0.99). Stratification by alcohol intake suggested a stronger reduction in risk in heavy drinkers and was confined to cancers caused by smoking and alcohol.

Conclusions: A very small inverse association between intake of total fruits and vegetables and cancer risk was observed in this study. Given the small magnitude of the observed associations, caution should be applied in their interpretation.

Reportagem da Agência EFE, no Estadão.com.br.

EcoDebate, 08/04/2010

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