Intakes of Fruit, Vegetables, Lung Cancer Risk in the NIH-AARP Study
Intakes of Fruit, Vegetables, Lung Cancer Risk in the NIH-AARP Study
Increased fruit and vegetable consumption may protect against lung cancer, although epidemiologic findings are inconclusive. The authors prospectively examined associations between lung cancer risk and intakes of fruit, vegetables, and botanical subgroups in 472,081 participants aged 50-71 years in the National Institutes of Health (NIH)-AARP Diet and Health Study. Diet was assessed at baseline (1995-1996) with a 124-item dietary questionnaire. A total of 6,035 incident lung cancer cases were identified between 1995 and 2003. Total fruit and vegetable intake was unrelated to lung cancer risk in both men and women. Higher consumption of several botanical subgroups, however, was significantly inversely associated with risk, but only in men. For example, the relative risks of lung cancer among men in the highest versus lowest quintiles of intake of rosaceae, convolvulaceae, and umbelliferae were 0.82 (95% confidence interval (CI): 0.73, 0.91), 0.86 (95% CI: 0.75, 0.96), and 0.86 (95% CI: 0.78, 0.96), respectively; corresponding relative risks in women were 0.97 (95% CI: 0.85, 1.12), 0.95 (95% CI: 0.83, 1.09), and 0.92 (95% CI: 0.80, 1.06). These results provide support for a protective role of specific botanical subgroups of fruits and vegetables in lung cancer prevention in men, although the findings could also be due to residual confounding by smoking or chance.
Lung cancer is the second most commonly diagnosed malignancy and the leading cause of cancer-related death among men and women in the United States. Given the poor overall 5-year survival rate (16%) and the lack of a proven effect of screening on lung cancer mortality, primary prevention remains the most effective way to reduce the health burden of this disease.
Cigarette smoking is the predominant cause of lung cancer, accounting for approximately 90% of all cases. Although cessation is the most effective preventive strategy among smokers, it is exceedingly difficult to quit. Even if they are successful, former smokers continue to have an increased risk of lung cancer compared with nonsmokers throughout their lifetime, and their options for primary prevention are unclear. Relatively few studies have examined risk factors for lung cancer in nonsmokers, even though 10% of lung cancer patients in the United States have never smoked.
Cigarette smoke contains reactive oxygen and nitrogen species that cause oxidative DNA damage when inhaled. Fruits and vegetables are rich sources of free-radical-scavenging antioxidant nutrients, including carotenoids and vitamin C, and may therefore protect against oxidative insults associated with cigarette smoking. Most prospective cohort studies have shown modest inverse associations between fruit and/or vegetable consumption and lung cancer risk, and both a pooled analysis of 8 studies and a separate meta-analysis of 11 studies indicated that this was driven primarily by fruit, not vegetable, intake. With the exception of cruciferous vegetables and citrus fruits, most botanical groupings of fruits and vegetables—classified according to their phytochemical content and proposed mechanisms of biologic action—have not been extensively investigated in epidemiologic studies of diet and lung cancer risk.
We prospectively examined whether fruit and vegetable consumption and intakes of specific botanical groups were related to lung cancer risk in the National Institutes of Health (NIH)-AARP Diet and Health Study. With over 6,000 incident lung cancer cases available for analysis, this is the largest prospective study to date to have examined these hypotheses.
Abstract and Introduction
Abstract
Increased fruit and vegetable consumption may protect against lung cancer, although epidemiologic findings are inconclusive. The authors prospectively examined associations between lung cancer risk and intakes of fruit, vegetables, and botanical subgroups in 472,081 participants aged 50-71 years in the National Institutes of Health (NIH)-AARP Diet and Health Study. Diet was assessed at baseline (1995-1996) with a 124-item dietary questionnaire. A total of 6,035 incident lung cancer cases were identified between 1995 and 2003. Total fruit and vegetable intake was unrelated to lung cancer risk in both men and women. Higher consumption of several botanical subgroups, however, was significantly inversely associated with risk, but only in men. For example, the relative risks of lung cancer among men in the highest versus lowest quintiles of intake of rosaceae, convolvulaceae, and umbelliferae were 0.82 (95% confidence interval (CI): 0.73, 0.91), 0.86 (95% CI: 0.75, 0.96), and 0.86 (95% CI: 0.78, 0.96), respectively; corresponding relative risks in women were 0.97 (95% CI: 0.85, 1.12), 0.95 (95% CI: 0.83, 1.09), and 0.92 (95% CI: 0.80, 1.06). These results provide support for a protective role of specific botanical subgroups of fruits and vegetables in lung cancer prevention in men, although the findings could also be due to residual confounding by smoking or chance.
Introduction
Lung cancer is the second most commonly diagnosed malignancy and the leading cause of cancer-related death among men and women in the United States. Given the poor overall 5-year survival rate (16%) and the lack of a proven effect of screening on lung cancer mortality, primary prevention remains the most effective way to reduce the health burden of this disease.
Cigarette smoking is the predominant cause of lung cancer, accounting for approximately 90% of all cases. Although cessation is the most effective preventive strategy among smokers, it is exceedingly difficult to quit. Even if they are successful, former smokers continue to have an increased risk of lung cancer compared with nonsmokers throughout their lifetime, and their options for primary prevention are unclear. Relatively few studies have examined risk factors for lung cancer in nonsmokers, even though 10% of lung cancer patients in the United States have never smoked.
Cigarette smoke contains reactive oxygen and nitrogen species that cause oxidative DNA damage when inhaled. Fruits and vegetables are rich sources of free-radical-scavenging antioxidant nutrients, including carotenoids and vitamin C, and may therefore protect against oxidative insults associated with cigarette smoking. Most prospective cohort studies have shown modest inverse associations between fruit and/or vegetable consumption and lung cancer risk, and both a pooled analysis of 8 studies and a separate meta-analysis of 11 studies indicated that this was driven primarily by fruit, not vegetable, intake. With the exception of cruciferous vegetables and citrus fruits, most botanical groupings of fruits and vegetables—classified according to their phytochemical content and proposed mechanisms of biologic action—have not been extensively investigated in epidemiologic studies of diet and lung cancer risk.
We prospectively examined whether fruit and vegetable consumption and intakes of specific botanical groups were related to lung cancer risk in the National Institutes of Health (NIH)-AARP Diet and Health Study. With over 6,000 incident lung cancer cases available for analysis, this is the largest prospective study to date to have examined these hypotheses.
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