Raw Garlic Consumption and Lung Cancer in a Chinese Population

Abstract

Background: Evidence of anticancer properties of garlic for different cancer sites has been reported previously in in vitro and in vivo experimental studies but there is limited epidemiologic evidence on the association between garlic and lung cancer.

Methods: We examined the association between raw garlic consumption and lung cancer in a case-control study conducted between 2005 and 2007 in Taiyuan, China. Epidemiologic data was collected by face-to-face interviews from 399 incident lung cancer cases and 466 healthy controls. We used unconditional logistic regression models to estimate crude and adjusted ORs (aOR) and their 95% confidence intervals (CI). Adjusted models controlled for age, sex, average annual household income 10 years ago, smoking, and indoor air pollution.

Results: Compared with no intake, raw garlic intake was associated with lower risk of development of lung cancer with a dose-response pattern (aOR for <2 times/week = 0.56; 95% CI, 0.39-0.81 and aOR for ≥2 times/week = 0.50; 95% CI, 0.34-0.74; Ptrend = 0.0002). Exploratory analysis showed an additive interaction of raw garlic consumption with indoor air pollution and with any supplement use in association with lung cancer.

Conclusions: The results of the current study suggest that raw garlic consumption is associated with reduced risk of lung cancer in a Chinese population.

Impact: This study contributes to the limited research in human population on the association between garlic and lung cancer and advocates further investigation into the use of garlic in chemoprevention of lung cancer. Cancer Epidemiol Biomarkers Prev; 25(4); 624-33. ©2016 AACR.

Figure 1

Charts depicting the joint effects of raw garlic consumption and selected risk factors in association with lung cancer. G+: any raw garlic intake; G-: no raw garlic intake; A+: age ≥55 years; A-: age <55 years; S+: ever smokers; S-: never smokers; IP+: high indoor air pollution; IP-: low/no indoor air pollution; Al+: alcohol ever drinkers; Al-: alcohol never drinkers; T+: Tea ever drinkers; T-: Tea never drinkers; Sp+: supplement users; Sp-: Supplement non-users. ^a adjusted for age (in years, except for interaction with age), sex, average household income 10 years ago (<1000 = 1, 1000-2499 = 2, 2500-4999 = 3, ≥5000 = 4), pack years of smoking (continuous, except for interaction with smoking), and indoor air pollution (an index of 0 = none, 1-2 = low and 3-5 = high indoor air pollution, except for interaction with indoor air pollution); ^b supplemental use includes intake of one or more of the following: vitamin A, beta-carotene, vitamin C, vitamin E, calcium, selenium, zinc or multivitamins. ✩ additive interaction between indoor air pollution and raw garlic consumption (RERI = 0.37, 95% CI: 0.05–0.68) as well as supplement use and raw garlic consumption (RERI = 0.41, 95% CI: 0.08–0.74)