Handbook of Vitamin C Research

Vitamin C Intake by Japanese Patients… 359seven other vegetables (onion, cucumber, bean sprout, snap bean, lettuce, bitter gourd,loofah). The fruit items included three citrus fruits (mandarin orange, other oranges, and 100percent orange juice) and 13 other fruits (apple, persimmon, strawberry, grape, melon,watermelon, peach, pear, banana, papaya, kiwi fruit, pineapple, and 100 percent apple juice).The frequency of intake of vegetables and fruits was classified by nine categories: ‗almostnever‘, ‗once to three times per month‘, ‗once to twice per week‘, ‗three to four times perweek‘, ‗five to six times per week‘, ‗once per day‘, ‗twice to three times per day‘, ‗four to sixtimes per day‘, and ‗seven or more times per day‘. Standard portion size was specified foreach item, with three choices of amount: small (50 percent smaller), medium (same as thestandard), and large (50 percent larger). Nine frequency choices for juice were available,ranging from ‗almost never‘ to ‗ten or more glasses per day‘. The amounts of fruit andvegetable consumed (in grams) per day were calculated from the responses recorded.Dietary Supplement UsageSpecific dietary supplements were classified into five categories, namely, multivitamin,beta-carotene, vitamin C, vitamin E, and miscellaneous, following the convention adopted bythe Japan Public Health Center-based prospective study on cancer and cardiovascular disease(Ishihara et al. 2003a). The brand name, frequency, duration and dosage of all supplementsconsumed by each participant were recorded. Users of dietary supplements were defined assubjects who used at least one category of dietary supplement on a weekly basis for one yearor longer (Ishihara et al. 2003a).Other MeasurementsA further question on ‗life-long physical activity involvement‘ was appended to thequestionnaire, defined as ―doing active sports or vigorous exercise long enough to getsweaty, at least twice a week‖, over the entire life course (O' Brien Cousins & Tan 2002).Response options were dichotomous: ‗has never been involved to not any more involved insuch activity‘ and ‗has always been involved in such activity‘.Two screening instruments, Medical Research Council‘s ―dyspnoea‖ scale (Bestall et al.1999) and the Australian Lung Foundation‘s ―Feeling Short of Breath‖ scale (The AustralianLung Foundation 2004), were used to assess respiratory symptoms of each individual. Thelatter scale consisted of five simple questions: (i) Do you cough several times most days? (ii)Do you bring up phlegm or mucous most days? (iii) Do you get out of breath more easilythan others your age? (iv) Are you over 40 years old? (v) Are you smoker or ex-smoker?Statistical AnalysisDescriptive statistics were first applied to summarise participant characteristics and lungfunction measures. The daily intakes of vegetables and fruits (g) were derived from the