ORIGINAL ARTICLENutritional risk factors for the development of chronic obstructive pulmonary disease (COPD) in male smokers
Introduction
Chronic obstructive pulmonary disease (COPD) is a leading cause of death, estimated by the World Health Organization (WHO) to be the sixth most common cause of death worldwide in 1990 and predicted to rise to third place by 2020.1 COPD is a prevalent and serious condition and its major risk factor, cigarette smoking, has been identified.2 However, only a minority of smokers develop clinically relevant disease. Although, the current understanding of a pathogenesis includes an “abnormal inflammation” as a response to various noxious agents, its various pathways are not clear. Oxidative stress, inflammation, tissue damage and tissue repair are parts of the complex procedure leading to COPD.3
There are some indications from epidemiological studies that dietary factors such as ample consumption of fruit may decrease COPD risk.4 Several studies, based on the hypothesis that antioxidants in food may protect the lungs against oxidant attack from the free radicals found in cigarette smoke, have found positive associations between low dietary intake of fruit and vegetables and decreased lung function in general populations.5 The major source of dietary antioxidants is fruits and vegetables. Dietary antioxidants, including tocopherols, ascorbate, and carotenoids as well as antioxidant non-nutritive substances such as flavonoids, which is a polyphenol, may prevent air pollution-induced oxidative stress in lungs. Especially, black tea, one of the most frequently consumed beverages worldwide, is a rich source of antioxidants. In fact, regular black tea consumption may very well be one of the major sources of antioxidant worldwide due to the high concentration of polyphenols in tea combined with the frequent consumption of this beverage,6 which is a popular beverage in Turkey and hence may be considered an important source of dietary flavonoids among Turks.
Tea contains more than 4000 chemical compounds that may affect the human body in many aspects. Black tea is produced by crouching fresh tea leaves, allowing enzyme-mediated oxidation to occur in a process commonly known as fermentation.7 Through fermentation, a large percentage of the catechins are converted to oligomeric theaflavins and polymeric thearubigins in black tea. The resulting brewed black tea contains 3–10% catechins, 2–6% theaflavins and >20% thearubigins.8 Moreover, it is important to consider that tea beverages often contain a millimolar concentration of caffeine that may affect some properties of the beverage.9
The dietary advice for weight-stable COPD patients is generally to eat a healthy diet, which is usually interpreted as a diet according to general dietary recommendations that is, low in fat, high in fiber, containing complex carbohydrates and including large quantities of fruit and vegetables.10 High intake of fruits and vegetables enhances ventilatory function, thereby reducing risk of COPD.
In this study, we investigated nutritional risk factors for the development of COPD in male smokers and for this purpose, we examined whether intakes with high-level antioxidant such as black tea, vegetables and fruits could play a protective role against COPD in male smokers.
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Materials and methods
Forty male patients with COPD defined as forced expiratory volume in 1 s FEV(1)/forced vital capacity FVC<70%, and FEV(1)<80% admitted in a reference university hospital between 2003 and 2004 in the South eastern Anatolia Region of Turkey. Control group included 36 healthy smokers living in the same geographic area were matched with COPD group by sex, age and smoking histories. For selecting individual for control group, a questionnaire that includes only questions about the socio-economic and
Results
Characteristics of patients with COPD and control groups are shown in Table 1. Cases and controls were similar in terms of BMI, age, smokers, living in urban, smoking parents and smoke exposure in work place ().
The means, SDs and the confidence intervals (95%) of five food groups and sugar and median of black tea consumption for the cases and controls are shown in Table 2. The mean of vegetables–fruits scores (63.81±6.910) and the median of the black tea 16.00(8–25) were significantly
Discussion
Population-based studies have found that tea drinkers tend to have a reduced risk of certain chronic diseases.7 The tea increases the level of cellular antioxidant defenses, thus lowering the risk of diseases involving adverse oxidative reactions.16 Tea was identified as the most significant source of flavonoid antioxidants. Flavonoids are hypothesized to be important determinants of diseases related to oxidative stress. Flavonol and flavone intake was positively associated with pulmonary
Acknowledgments
We thank Prof. Dr. Yusuf CELİK (Head of Biostatistics Department of Medicine Faculty, Dicle University) for helping statistical evaluations.
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