From Reuters Health Information CME
CME/CE Released: 02/19/2010February 19, 2010 — A diet rich in raw fresh fruits, fruit juices, and vegetables may improve lung function and reduce exacerbations in patients with chronic obstructive pulmonary disease (COPD), according to a prospective randomized trial from Greece.
"There is increasing evidence that COPD is characterized by increased airway and systemic inflammation, which partially is triggered by the aggravated oxidative stress that is prevalent in COPD patients," the authors write in an article published online February 11 in the European Respiratory Journal.
They theorized that balancing oxidative stress through dietary intervention might help protect the lungs in COPD.
Dr. Demosthenes Makris and co-authors at the University of Thessaly School of Medicine, Larissa, enrolled 120 patients with COPD (mean age 68 years; 88% men) in a 3-year open-label study. All patients completed dietary questionnaires at 6-month intervals.
Sixty patients were randomized to the intervention arm, in which they were instructed to increase their fresh fruit and vegetable consumption by at least one portion per day. In the control group, diet was not discussed.
The groups were similar at baseline in demographic factors, smoking or smoking cessation, dietary habits, and spirometry results. They were also similar in terms of physical activity, changes in body mass index, or alcohol consumption during the study.
At baseline, groups were similar in their consumption of vegetables and fruits, the report indicates. Throughout the study, diets in the control group remained unchanged, but antioxidant consumption rose significantly in the intervention group (p = 0.001).
In the year before the study, mean annual exacerbation rates were similar in the intervention group (0.45) and control group (0.51, p = 0.01). During the study, however, mean annual rates were significantly lower in the intervention group (0.18 vs 0.34, p = 0.001).
The high-antioxidant diet was also associated with an annual increase in forced expiratory volume in 1 second (FEV1), whereas mean FEV1 decreased in the control group (p = 0.03). Forced vital capacity was also significantly higher at the end of the study in the intervention group.
The authors report that the association of excess antioxidant consumption with the improvement in FEV1 was significant (p <>
Dr. Makris and his colleagues point out that they did not measure oxidative stress objectively during the study, and they assessed exacerbations simply by questioning the subjects.
Still, they say, "Our findings suggest that a dietary (change) to higher antioxidant foods intake may be associated with improvement in lung function."
"The place of dietary interventions in the management of COPD warrants consideration," the researchers conclude.
Eur Respir J. 2010.
Additional Resource
More information on COPD is available on the National Heart Lung and Blood Institute's Web site.
Clinical Context
Consumption of foods rich in antioxidants may be beneficial to lung function in patients with COPD because antioxidants may protect against oxidative damage to lung tissue and prevent damage from smoking and air pollution.
This is an open-label randomized clinical trial of patients with COPD to examine the association between increased antioxidant intake through fruit and vegetable consumption and lung function assessed by FEV1 during 3 years of follow-up.
Study Highlights
- Included were patients attending a community primary care clinic in a rural area of Greece who were diagnosed with COPD by the GOLD criteria based on medical history, physical signs, and lung function tests and who were free of COPD exacerbation for at least 4 weeks.
- Excluded were patients with favorable response to bronchodilators, history of asthma, atopy, and allergic rhinitis or continuous use of systemic corticosteroids for 30 days or more.
- Following a recruitment period of 2 months, there was a run-in followed by outpatient visits every 6 months for lung function assessment.
- 120 eligible patients were randomly assigned to a diet rich in fruits and vegetables (n = 60) or usual diet (n = 60).
- At baseline, all patients underwent physical examination, had BMI and lung function assessed, and had their comorbidities assessed using the Charlson index.
- Every 6 months during the study, lung function was assessed by spirometry after premedication with 200 μg salbutamol via metered dose inhaler.
- Food intake was assessed using a food questionnaire modified for antioxidant intake and adjusted for the rural diet in this region, with questions for 38 different food items such as salads and raw vegetables, fresh fruits, and pure fruit juices.
- 5 categories of frequency of intake, from once or more than once daily to less than once weekly or none, were used.
- An overall fresh fruits and vegetables score was computed.
- Intake of cereals, meats, and fish was also reported.
- The intervention group was counseled to add at least 1 portion of fruits or vegetables to the baseline consumption level at each outpatient visit.
- The control group received no dietary advice.
- Both groups received similar COPD care and medications and management of exacerbations by standard clinical guidelines.
- Participants were not blinded, but assessors of lung function were blinded to assignment.
- Primary outcome was change in FEV1 after bronchodilator administration compared with baseline.
- Other outcomes such as quality of life and perceived symptomatology were not reported.
- Mean age was 68 years, most participants were white, 87.5% were men, and 47% had cardiovascular problems.
- By GOLD criteria, 18.5% were in stage I, 65.8% in stage II, 12.5% in stage III, and 3.3% in stage IV COPD.
- During the study, 19.1% stopped smoking, with no difference in quit rate between the 2 groups.
- Participants attended 794 of 840 follow-up visits, with no differences between the 2 groups.
- The intervention group consumed significantly more fruits and vegetables than the control group.
- The mean annual exacerbation rates were 0.45 and 0.51 in the intervention and control groups, respectively.
- During the study, the mean annual exacerbation rates were 0.18 and 0.34, respectively (both significantly lower than baseline).
- The difference in exacerbations between the 2 groups was significant.
- The mean annual change in FEV1 was 0.35 overall for both groups.
- There was a significant association between increased consumption of fruits and vegetables and change in FEV1.
- FEV1 improved in the intervention group while worsening in the control group.
- This improvement was seen for all types of fruits and vegetables.
- The improvement remained significant after controlling for sex, age, smoking status, comorbidities, and exacerbations.
- Meat consumption was reduced in the intervention group (1.90 servings per day at baseline vs 1.7 servings per day), but this was not statistically significant.
- There was no change in meat consumption in the control group.
- The authors concluded that a diet rich in fruits and vegetables had the potential to improve lung function in patients with COPD.
Clinical Implications
- Increased consumption of fruits and vegetables in patients with COPD is associated with improved FEV1 and reduced exacerbations during 3 years of follow-up.
- Increased consumption of fruits and vegetables by 1 serving daily is not associated with significant reduction in meat intake.
