Handbook of Vitamin C Research

360Fumi Hirayama and Andy H. Leefrequency and quantity recorded, accounting for the edible portion of each food. For everyunit (per 100g) of food intake, its vitamin C content (mg) was retrieved from the JapaneseFood Composition Table; see Appendix. The total dietary vitamin C intake for each subjectwas estimated by multiplying each vitamin C content with the corresponding quantity of foodconsumed and then summing across all foods. The amounts of dietary vitamin C intakebetween case and control groups were compared by t-tests, whereas chi-square tests wereconducted for vitamin C and multivitamin supplements usage. All statistical analyses wereundertaken using the SPSS for Windows package version 13.ResultsTable 1 presents the characteristics of the participants by case-control status and gender.The average age of subjects was about 66 years. The mean body mass index (BMI, five yearsago) of COPD patients was lower than that of controls. The majority of participants had highschool or below education and were seldom involved in physical activity over the life course.A substantial proportion of COPD patients (21.8% for male and 27.3% for female) continuedto smoke after their diagnosis of COPD and, as expected, had significantly lower level oflung function measures than controls.Table 1. Characteristics of participants by case-control status and genderVariable COPD patients ControlsMale(n = 244)Mean age (years) 66.51(SD 6.82)Female(n = 34)66.10(SD 6.13)Male(n = 272)65.15(SD 5.41)Female(n = 68)66.12(SD 5.76)Mean BMI five years ago (kg/m 2 ) 22.09 20.67 23.61 23.30(SD 2.94) (SD 3.89) (SD 2.85) (SD 3.25)Education: high school or below 195 (80.2%) 26 (78.8%) 166 (61.9%) 47 (70.1%)Life-long physical activity: neverto not any more involved185 (75.8%) 29 (85.3%) 182 (68.2%) 56 (82.4%)Alcohol drinkers 150 (61.5%) 8 (23.5%) 202 (74.5%) 21 (30.9%)Cigarette smoking statusEx-smoker 188 (77.4%) 20 (60.6%) 133 (49.1%) 3 (4.4%)Current smoker 53 (21.8%) 9 (27.3%) 63 (23.2%) 2 (2.9%)Mean smoking (pack-years) 65.03(SD 24.91)FEV 1 1.64(SD 0.69)FVC 3.08(SD 0.83)FEV 1 /FVC (%) 52.70(SD 14.71)FEV 1 % predicted 56.68(SD 22.32)43.25(SD 31.67)1.15(SD 0.47)2.07(SD 0.52)55.30(SD 14.47)56.52(SD 19.40)30.90(SD 28.81)2.56(SD 0.51)3.31(SD 0.60)78.06(SD 5.96)86.54(SD 14.04)2.04(SD 9.68)1.76(SD 0.35)2.17(SD 0.41)81.74(SD 5.66)93.85(SD 13.76)