Does Garlic Reduce Risk of Colorectal Cancer? A Systematic Review , ,3

Abstract

Colorectal cancer (CRC) is the 3rd leading cause of cancer death in the United States and the 2nd leading cause of cancer death in Australia. Environmental factors play important roles in the multiple-stage process of CRC and nutritional intervention has been identified as playing a major role in its prevention. The aim of this study was to review systematically the scientific evidence from all studies conducted over the last decade that examined effects of garlic on CRC. Levels of evidence were ranked from level I to level V according to study designs and the quality of each study was assessed against a set of quality criteria based on those used by the National Health and Medical Research Council in Australia. One randomized controlled trial (RCT, level II) reported a statistically significant 29% reduction in both size and number of colon adenomas in CRC patients taking aged garlic extract. Five of 8 case control/cohort studies (level III) suggested a protective effect of high intake of raw/cooked garlic and 2 of 8 of these studies suggested a protective effect for distal colon. A published meta-analysis (level III) of 7 of these studies confirmed this inverse association, with a 30% reduction in relative risk. Eleven animal studies (level V) demonstrated a significant anticarcinogenic effect of garlic and/or its active constituents. On balance, there is consistent scientific evidence derived from RCT of animal studies reporting protective effects of garlic on CRC despite great heterogeneity of measures of intakes among human epidemiological studies.

Comparison of the Main Bioactive Compounds and Antioxidant Activity from Garlic Water-soluble and Garlic Oil

“…Vitamin, proteins, lipids, trace elements Se, flavonoids and at least 33 different organosulfur compounds are identified on garlic [9,10]. Organosulfur compounds are divided into water soluble organosulfur constituents mainly SAC (S-allylcystein), NAC (N-acetylcysteine [3,11] and oil soluble organsulfur constituents such as DATS (diallyl trisulfide), DADS (diallyl disulfide), DAS (diallyl sulfide).…”

Traditional Chinese medicine in the prevention and treatment of cancer and cancer metastasis

“…Garlic extracts are primarily composed of sulphur compounds, particularly allicin, diallyl sulphide (DAS), diallyl disulphide (DADS), diallyltrisulphide (DATS) and ajoene, all of which exhibit anticancer activities. The antiproliferative effects of the extracts are associated with the induction of apoptosis (20,57). Morphological changes and DNA fragmentation have been observed in cells treated with DADs and DATs (58,59).…”

Changes in antioxidant capacity, levels of soluble sugar, total polyphenol, organosulfur compound and constituents in garlic clove during storage

“…Garlic (Allium sativum L.) belongs to the vegetables of the Allium genus, it has a long history as being a food having a unique taste and odor (Ariga and Seki, 2006;Ngo et al, 2007). Nowadays, Garlic has been not only widely used in antibacterial, antiviral, antifungal and antiprotozoal, but also beneficial effects on the cardiovascular and immune systems (Harris et al, 2001).…”