A considerable body of empirical evidence underscores the substantive impact of nutritional factors on the health of the respiratory system [1]. Notably, a predominant focus within the realm of nutritional research has been directed towards the consumption of fruits, vegetables, and antioxidant micronutrients. This focus is attributed to the susceptibility of pulmonary tissues to a diverse array of oxidative insults, coupled with the pivotal function that antioxidant defenses serve in safeguarding the lungs against detrimental outcomes. A mounting, albeit incongruent, corpus of evidence highlights a potential correlation between diminished dietary intake of fruits, antioxidants - including vitamins A, C, and E - and the prevalence of obstructive airway conditions. Additionally, inconsistencies have been observed in adult lung function as assessed through spirometric measurements of forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) [2].

Recent population-based investigations have revealed associations between compromised lung function and reduced antioxidant intake, as well as decreased serum levels of antioxidants. If causal, the link between diminished antioxidant intake and adult lung function might be attributed to accelerated declines in lung function during adulthood, acute reversible effects, and/or enduring repercussions of inadequate intake during crucial periods of childhood growth and maturation [3]. Despite this, only limited population-based inquiries have delved into the relationship between antioxidant intake and pulmonary function in childhood [4]. Evident in a cross-sectional analysis, FEV1 levels were positively correlated with the frequency of fresh fruit consumption, and to a lesser extent with the intake of green vegetables and salads [5].

Notably, FEV1 exhibited no discernible correlation with serum levels of vitamin C, underscoring the potential influence of other micronutrients present in fruits. Studies that holistically consider both dietary and comprehensive nutrient intake, inclusive of nutrients derived from both natural food sources and dietary supplements, hold promise in elucidating the potential significance of the collective array of antioxidants inherent in whole foods, as well as the specific roles of individual vitamins. Grounded in available evidence for both adult and pediatric populations, it was postulated that an inadequate intake of fruits, vegetables, and antioxidant vitamins A, C, and E could be linked to deficits in childhood lung function encompassing FVC, FEV1, and forced expiratory flow within the range of 25 to 75 percent of forced vital capacity (FEF25–75) [6, 7].

This Open Label Before and After study, was conducted within a tertiary care center. The subjects were selected from the pulmonary outpatient department and consisted of 86 individuals with confirmed COPD exhibiting FEV1 < 80%, FEV1/FVC < 70%, and aged between 40 to 70 years, representing both genders. The mean duration of disease ranged between 10 to 15 years. Participants with respiratory disorders other than COPD, malignancy, overt cardiac failure, recent surgery, severe endocrine, hepatic, or renal diseases, and those under anticoagulant medication were excluded.

A comprehensive history was taken, coupled with thorough general and systemic examinations. Parameters including age, body weight, standard height, body mass index (BMI), and blood pressure were measured. Following informed consent, each patient was administered Tablet Limcee (500 mg bd), containing Vitamin-C or Ascorbic acid, for a duration of twelve weeks. The treatment regimen remained constant throughout the study, and participants were advised to maintain their dietary habits. Lifestyle changes or health events were documented during periodic interviews. No additional oral vitamin supplements were utilized by the participants either before or during the study period. After twelve weeks, investigations were conducted.

Venous blood samples were collected from all participants under aseptic conditions, following a 12- hour fasting period, in both plain and fluoride bulbs. To eliminate diurnal variation in oxidative stress parameters, samples were drawn in the morning. Serum was separated through centrifugation at 3000 rpm for 10 minutes and subjected to various assays. The evaluations encompassed several parameters 'Before' and 'After' the vitamin C supplementation period.

Pulmonary function tests were conducted using body plethysmography. The procedure was consistent across all subjects, performed in a seated position by a single technician, with the highest of three technically acceptable measurements included in the analyses.

Blood was drawn for routine biochemical analyses, assessment of lipid peroxidation products, and antioxidant enzymes. Routine biochemical assays followed established techniques. Lipid peroxidation was quantified through spectrophotometry at 535 nm, measuring thiobarbituric acid reactive substances (MDA) concentrations. Erythrocyte superoxide dismutase (SOD) levels were determined via pyrogallol autoxidation inhibition. Glutathione peroxidase (GPx) activities were assessed in washed red blood cells.

Following 12 weeks, spirometry and measurements of MDA, SOD, and GPx were reiterated. All patients continued to receive standard supportive COPD treatment during the study. The outcome variables comprised FEV1, FEV1/FVC, MDA levels, SOD levels, and GPx levels. Statistical analysis was performed using the t-test, with P values < 0.05 considered statistically significant.

A total of 86 patients, comprising 56 males and 30 females, were enrolled in this investigation. The participants displayed a characteristic late middle-aged profile and an average smoking history. Over the course of twelve weeks, the administration of Vitamin-C supplementation (Tablet Limcee) at a dosage of 500 mg twice daily produced noteworthy outcomes. Specifically, a statistically significant reduction in the mean level of malondialdehyde (MDA) was observed.

Additionally, significant increases were evident in the mean levels of superoxide dismutase (SOD) and glutathione peroxidase (GPx) following twelve weeks of vitamin C supplementation. Conversely, no statistically significant enhancements in FEV1 and FEV1/FVC were observed post twelve weeks of vitamin C supplementation. The findings of the present study are summarized in Tables 1-3 and Figures 1 and 2.

Table 1: Gender wise demographics in COPD patients.

Table 2: Oxidative Stress parameters before and after Vitamin C supplementation.

Table 3: Pulmonary function before and after Vitamin C supplementation

 Figure 1: Mean Superoxide Dismutase (SOD) Before and After Vitamin C supplement

Figure 2: Mean MDA and GPx Before and After Vitamin C supplement

Our study underscores the potential detrimental impact of insufficient antioxidant vitamin intake on pulmonary function in patients. Specifically, we observed deficiencies in FVC, FEV1, and FEF25–75 among female participants with notably low levels of both dietary and overall vitamin C intake. A similar pattern was noticed among male participants with insufficient consumption of fruit juices, a source often supplemented with vitamin C [8].

Our data, which indicate a lack of statistically significant dose-response relationships between antioxidant vitamin intake and lung function levels, raise the intriguing possibility that surpassing the recommended daily allowance of antioxidant vitamins might not confer added protection for lung function. Our findings, highlighting the association between inadequate vitamin C intake and lung function deficits, align with previous studies in adults demonstrating lower FVC and FEV1 values in individuals with reduced vitamin C intake. However, our results contrast with the solitary study examining the correlation between vitamin C and lung function [9]. Cook et al.'s cross-sectional study involving 50 subjects in the UK reported positive associations between FEV1 and the consumption frequency of fresh fruits, green vegetables, and salads. Notably, this association was not found with serum vitamin C levels, suggesting the potential involvement of other nutrients present in fruits. Additionally, multiple studies in adults have reported the protective influence of fruit consumption on lung function and obstructive airway conditions [10]. Discrepancies in findings between our and other investigations may stem from variations in dietary habits across populations or differences in diet assessment methodologies.

It is pertinent to acknowledge that while dietary assessments of vitamin intake through methods like food frequency questionnaires can be imprecise, the absence of an association could stem from a temporal misalignment between cross-sectional lung function studies, which encapsulate lifelong growth, and serum vitamin C levels—a water-soluble vitamin with a relatively short half-life [11]. Short-term biomarkers like serum levels might yield less precise estimates of average childhood levels compared to questionnaire methods that characterize habitual intake, such as food frequency questionnaires.

Numerous mechanisms have been explored to explain vitamin C's protective influence on lung function. This vitamin acts as a critical extracellular antioxidant within the respiratory lining fluid, safeguarding proteases, antiproteases, epithelial cells, and immune cells against oxidative stress. Lower levels of vitamin C may render the lung more susceptible to oxidative damage. Notably, trials have demonstrated the protective effects of vitamin C supplementation on short- term lung function changes in individuals exposed to high levels of oxidative air pollutants [12]. Furthermore, vitamin C might contribute positively to lung health, diminishing airway hyperreactivity—two factors that play a pivotal role in adult lung function [13].

While we cannot currently discern whether the association between lung function and antioxidant vitamins and juice intake stems from improved pulmonary function, protection against bronchospasm, or reduced airway hyperreactivity in participants due to the cross- sectional nature of our analysis, future longitudinal follow-up of the cohort could provide insight into both acute and chronic effects on lung function growth and its maximum attainment at maturity [14-16].

It is pertinent to consider the possibility that the diverse range of antioxidants may display varying associations with the disease and lung function. In summary, the study results indicate that while exogenous supplementation of vitamin C did not exert a notable impact on spirometric measurements, it did contribute to the reduction of MDA levels, indicating a potential mitigation of further oxidative damage. Ultimately, the study underscores the intricate relationship between antioxidant supplementation and COPD management, revealing that a 12- week regimen of daily vitamin C supplementation, when added to the standard treatment, yielded certain clinical benefits, including the augmentation of select endogenous antioxidants.

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