Effects of mediterranean diet on lung function in smokers: a randomised, parallel and controlled protocol

BACKGROUND: There is evidence of an association between pulmonary function and various nutrients, although no association has been observed in our setting between the Mediterranean Diet (MD) eating pattern and improved lung function. The objective of this study is to evaluate the effect of an intervention designed to increase MD adherence on lung function in smokers with no previous respiratory disease. METHODS/DESIGN: Randomized, controlled, parallel clinical trial. Setting: primary health care centers in Catalonia (Spain). Participants: Current smokers (cumulative > 10 pack-years) aged 35–70 years, with Internet access, who provide signed informed consent to participate. Intervention: A nutritionist will conduct a 2-year multicomponent intervention to increase MD adherence, based on: 1) a personalized dietary-nutritional education intervention, 2) a Web 2.0 approach, the DIET Blog of nutritional information, and 3) group sessions to increase motivation to increase MD adherence and motivation to make changes in eating habits. Annually, an office visit and one group session will reinforce the nutritional intervention. The control group will follow their usual diet, with general nutritional counselling. In both groups, a 14-item questionnaire will evaluate individual MD dietary patterns and forced spirometry will assess lung function. Analysis: Intention to treat. The unit of analysis will be the individual smoker. Primary outcome is lung function indicated by spirometry, FVC, FEV1 and FEV1/FVC %. Lung function parameters in both groups will be compared by adherence to the MD pattern. DISCUSSION: The DIET study could contribute data on a protective action of the MD pattern on lung function in smokers. If so, this population may benefit from a nutritional intervention, along with the fundamental recommendation to stop smoking. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02151669. Registered 26 May 2014.