Fruit and veg fans are likely to have better respiratory health than those with less healthy diets, suggests a recent review, highlighting the role of antioxidants in fruit and vegetables in protecting against inflammatory reactions and obstructed airways.
The evidence, compiled from trials published since 1998, suggests strong links between diet and the incidence of asthma and COPD, with an intake of vitamins C and E, beta-carotene and selenium most important.
A team from Nottingham reported last year on research showing that vitamin C protects the lungs, and may lower the risk of developing chronic obstructive pulmonary disease. There has also been recent evidence linking a diet high in fish and fruit with lower risk of respiratory diseases and winter coughs in children.
Led by Dr Barrie Margetts at the Institute of Human Nutrition at the University of Southampton, UK, the review focused on the role of dietary factors in the development of asthma and chronic obstructive pulmonary disease (COPD). Researchers used scientific literature which explored the relationship between diet, asthma and obstructive lung disease. Outcomes were defined based on diagnosis of asthma or COPD and other respiratory symptoms and changes in lung function.
But while there is strong evidence to suggest the importance of diet for respiratory health, most of this comes from a variety of different studies rather than specific case-control studies, said Dr Margetts, making it impossible to find direct links between what people eat and respiratory health.
"The evidence from the studies suggests that diet does play a role in the incidence of asthma and COPD, but the causality of association cannot be confirmed because of the observational nature of most of the studies," said Dr Margetts.
"However, on the basis of the evidence, it seems justified to promote a healthy diet, high in fruits, vegetable, and wholegrain foods and low in alcohol and fatty foods as set out in existing guidelines for prevention of cardiovascular disease and cancer."
The collected evidence also provides a basis for further research, said Dr Margetts.