Lina Mu

M.D., Ph.D

University at Buffalo

Associate Professor

PLCO (Learn more about this study)

PLCO-315

Oct 10, 2017

The association of garlic intake on total cancer incidence and mortality

Garlic, an Allium vegetable, contains a high composition of flavonoids and organosulfur compounds that have shown inhibitory actions against tumors in animal and in vitro studies. Diallyl sulfide (DAS), an organosulfur compound, rich in garlic, prevents the development of colon carcinomas, esophageal carcinomas, pulmonary carcinomas, and forestomach tumors in mice (Takada et al., 1994). Furthermore, these compounds play a role in scavenging free radicals, modulating the immune system, inhibiting carcinogen-induced DNA binding and adduct formation, and inhibiting the initiation and promotion of carcinogenesis (Fleischauer & Arab, 2001).
Existing epidemiologic studies have shown an association between garlic and reduced risk of cancers including stomach, colon, breast, lung, and esophagus (Fleischauer & Arab, 2001). A pooled analysis of 12 studies reported that high garlic consumption reduced the risk for gastric cancer (odds ratio, 0.53; 95% confidence interval, 0.40–0.65) (Zhou et al., 2011). A meta-analysis reported an approximately 37% reduction in colorectal cancer risk in case–control studies (combined risk estimate=0.63, 95 % CI 0.48, 0.82) and no significant association in cohort studies OR=0.93; 95 % CI: 0.82, 1.06) (Chiavarini, Minelli, & Fabiani, 2016). Limited studies exist regarding breast cancer. One case-control study conducted in France found that those who consumed onion and garlic >16 times/week had a 60% reduced risk of breast cancer compared to those who consumed ≤6 times/week (95%CI: 0.17, 0.52) (Challier, Perarnau, & Viel, 1998). Another study in Italy found a 10% reduced risk of breast cancer associated with high garlic consumption (Franceschi et al., 1998). Epidemiologic evidence for garlic and lung cancer are inconsistent, but more recent studies suggests that consumption of raw garlic (≥2 times per week) is protective against lung cancer (Jin et al., 2013; Lin & Cai, 2012; Myneni et al., 2016). Very few or no studies exist for other types of cancer including prostate, pancreas, kidney, leukemia, and bladder. Many of the previous studies were limited to European and Asian countries. There are a limited number of studies regarding garlic consumption and cancer incidence/mortality in the United States.
The PLCO study collected the frequency of garlic intake in the dietary questionnaire at baseline (DQX) and garlic supplement intake in the diet history questionnaire (DHQ). We hypothesize that garlic intake has a protective effect on overall cancer incidence and mortality as well as several specific types of cancer including lung, breast, colorectal, pancreatic, and stomach cancer.

1) To examine the association between garlic intake (food and supplements) and risk of total cancer incidence and mortality. Garlic intake will be assessed using the baseline dietary questionnaire (DQX) and diet history questionnaire (DHQ).

2) To examine the association between garlic intake (food and supplements) and risk of site-specific cancers including lung, prostates, breast, pancreatic, and ovarian cancers.

References:
Challier, B., Perarnau, J.-M., & Viel, J.-F. (1998). Garlic, onion and cereal fibre as protective factors for breast cancer: a French case–control study. European journal of epidemiology, 14(8), 737-747.
Chiavarini, M., Minelli, L., & Fabiani, R. (2016). Garlic consumption and colorectal cancer risk in man: a systematic review and meta-analysis. Public health nutrition, 19(2), 308-317.
Fleischauer, A. T., & Arab, L. (2001). Garlic and cancer: a critical review of the epidemiologic literature. The Journal of nutrition, 131(3), 1032S-1040S.
Franceschi, S., Parpinel, M., La Vecchia, C., Favero, A., Talamini, R., & Negri, E. (1998). Role of different types of vegetables and fruit in the prevention of cancer of the colon, rectum, and breast. Epidemiology, 338-341.
Jin, Z.-Y., Wu, M., Han, R.-Q., Zhang, X.-F., Wang, X.-S., Liu, A.-M., . . . Zhao, J.-K. (2013). Raw garlic consumption as a protective factor for lung cancer, a population-based case–control study in a Chinese population. Cancer prevention research.
Lin, Y., & Cai, L. (2012). Environmental and dietary factors and lung cancer risk among Chinese women: a case-control study in southeast China. Nutrition and cancer, 64(4), 508-514.
Myneni, A. A., Chang, S.-C., Niu, R., Liu, L., Swanson, M. K., Li, J., . . . Zhang, Z.-F. (2016). Raw garlic consumption and lung cancer in a Chinese population. Cancer Epidemiology and Prevention Biomarkers, cebp. 0760.2015.
Takada, N., Kitano, M., Chen, T., Yano, Y., Otani, S., & Fukushima, S. (1994). Enhancing effects of organosulfur compounds from garlic and onions on hepatocarcinogenesis in rats: association with increased cell proliferation and elevated ornithine decarboxylase activity. Cancer Science, 85(11), 1067-1072.
Zhou, Y., Zhuang, W., Hu, W., Liu, G. J., Wu, T. X., & Wu, X. T. (2011). Consumption of large amounts of Allium vegetables reduces risk for gastric cancer in a meta-analysis. Gastroenterology, 141(1), 80-89.