Nutrition and Oral Medicine (Nutrition and Health)

208 Part IV / Select Diseases and Conditions3.1. Food Groups and Items3.1.1. FRUITS AND VEGETABLESAmong studies investigating a possible link between OPC and the intake of variousfood groups and items, the most consistent finding has been an inverse associationbetween cancers at these anatomical sites and the consumption of fruits and/or vegetables(8–25). That is, the risk of OPC tends to decrease with increased fruit andvegetable intake. Table 1 presents findings from selected studies that investigated therelationship between OPC and the consumption of fruits and vegetables.3.1.1.1. FruitsWith few exceptions, high, relative to low, fruit consumption has been linked to areduced risk of OPC. In a large case–control study conducted in the United States (9,11),risk reductions on the order of 40 to 80% were observed for high, relative to low, totalfruit consumption among both blacks and whites and among males and females. Moreover,when fruit subgroups were analyzed separately, high intakes of citrus, dark yellow,and other fruits—including watermelon, strawberries, apples, pears, and bananas—were always associated with a reduced OPC risk across the racial and gender groups(9,11). In a more recent report from a prospective cohort study involving more than34,000 Iowan women followed for 14 yr, total fruit intake was again associated with aprotective effect in terms of upper aerodigestive tract (oral/pharyngeal, esophageal,gastric, and laryngeal) cancers, but the finding was not statistically significant (notshown in Table 1) (21). A large case–control study conducted in northeastern and centralItaly also linked most types of fruit to a reduced risk of OPC, although the reductionassociated with high consumption was greater for citrus (50%) than noncitrus (30%)fruits and statistically significant for citrus fruits only (23). Notably, the beneficialeffects associated with citrus-fruit intake in that study were derived from the consumptionof both the whole fruit and fruit juices.3.1.1.2. VegetablesFindings regarding vegetable intake have also suggested a protective effect, but notnecessarily across all studies or across all vegetable and population subgroups. In thelarge US case–control study, patterns of OPC risk reduction were seen for total vegetableconsumption among black males, to a lesser extent among females, but not amongwhite males, whose ORs remained at or near 1.0 for each level of consumption (9,11).In that study, however, vegetables most likely to be eaten raw, including lettuce, cucumbers,fresh tomatoes, carrots, and coleslaw, were associated with 60 to 80% reductionsin OPC risk among high, relative to low, consumers in both races and genders. In thecohort study of Iowan women, an inverse relationship was observed for total vegetableintake in relation to the risk of upper aerodigestive tract cancer, although, as with fruits,the finding was not statistically significant (21). That study did, however, report astatistically significant reduction in cancer risk with regard to the intake of yellow andorange vegetables. In the Italian case–control study (23), a high intake of both raw andcooked vegetables was associated with approx 50% reductions in OPC risk.Although individual vegetable items have not been consistently included across studies,carrots (9,12,16,20,23,25,26) and tomatoes (9,12,16,17,20,23,24) have emerged as