Antioxidants in the chemoprevention of colorectal cancer and colorectal adenomas in the general population: a systematic review and meta-analysis

Abstract

The review demonstrates that antioxidants (vitamin A, C and E, selenium and β-carotene), as single agents, in combination with other antioxidants or in combination with other agents, are not effective in the chemoprevention of colorectal neoplasia in the general population. This questions their involvement in future randomized controlled trials of chemoprevention in colorectal cancer.

Efficacy of Vitamin C Supplements in Prevention of Cancer: A Meta-Analysis of Randomized Controlled Trials

“…The findings of our analysis were consistent with those of previous meta-analyses of RCTs, which concluded no association between vitamin C and prostate, colorectal, and gastrointestinal cancers. 9 10 23) Our findings, however, were inconsistent with those of previously published preclinical in vivo or in vitro studies on this issue. 24 25 26) In 2005, an in vitro experiment conducted by Abdel-Latif et al 27) suggested the efficacy of vitamin C supplements in facilitating apoptosis of esophageal cancer cells when used in conjunction with chemotherapy.…”

Efficacy of Vitamin C Supplements in Prevention of Cancer: A Meta-Analysis of Randomized Controlled Trials

“…The findings of our analysis were consistent with those of previous meta-analyses of RCTs, which concluded no association between vitamin C and prostate, colorectal, and gastrointestinal cancers. 9 10 23) Our findings, however, were inconsistent with those of previously published preclinical in vivo or in vitro studies on this issue. 24 25 26) In 2005, an in vitro experiment conducted by Abdel-Latif et al 27) suggested the efficacy of vitamin C supplements in facilitating apoptosis of esophageal cancer cells when used in conjunction with chemotherapy.…”

Dietary Total Antioxidant Capacity and Colorectal Cancer in the Italian EPIC Cohort

“…However, when colon and rectal cancers were considered separately, increasing TAC intake was associated with reducing risk of colon cancer and increasing risk of rectal cancer, both with significant trends. Intake of individual antioxidants (vitamin C, vitamin E and ß-carotene) was not significantly associated with colorectal cancer risk, in agreement with the 2007 WCRF/AICR panel report and recent reviews [ 15 , 16 , 28 ]. Thus, our evaluation of the total antioxidant capacity of the diet has found effects not revealed by investigation of individual antioxidants.…”

Correction: Dietary Supplement Use and Colorectal Adenoma Risk in Individuals with Lynch Syndrome: The GEOLynch Cohort Study

“…The association between dietary supplement use and sporadic colorectal adenoma risk in the general population has been investigated in many epidemiological studies. [23][24][25][26][27] Our findings for dietary supplement use and colorectal adenoma risk in individuals with Lynch syndrome were largely consistent with findings in the general population. Calcium supplement use might contribute to a lower risk of colorectal adenomas in the general population.…”

Efficacy of Vitamin C Supplements in Prevention of Cancer: A Meta-Analysis of Randomized Controlled Trials

“…The findings of our analysis were consistent with those of previous meta-analyses of RCTs, which concluded no association between vitamin C and prostate, colorectal, and gastrointestinal cancers. 9 10 23) Our findings, however, were inconsistent with those of previously published preclinical in vivo or in vitro studies on this issue. 24 25 26) In 2005, an in vitro experiment conducted by Abdel-Latif et al 27) suggested the efficacy of vitamin C supplements in facilitating apoptosis of esophageal cancer cells when used in conjunction with chemotherapy.…”

Dietary Total Antioxidant Capacity and Colorectal Cancer in the Italian EPIC Cohort

“…However, when colon and rectal cancers were considered separately, increasing TAC intake was associated with reducing risk of colon cancer and increasing risk of rectal cancer, both with significant trends. Intake of individual antioxidants (vitamin C, vitamin E and ß-carotene) was not significantly associated with colorectal cancer risk, in agreement with the 2007 WCRF/AICR panel report and recent reviews [ 15 , 16 , 28 ]. Thus, our evaluation of the total antioxidant capacity of the diet has found effects not revealed by investigation of individual antioxidants.…”

Correction: Dietary Supplement Use and Colorectal Adenoma Risk in Individuals with Lynch Syndrome: The GEOLynch Cohort Study

“…The association between dietary supplement use and sporadic colorectal adenoma risk in the general population has been investigated in many epidemiological studies. [23][24][25][26][27] Our findings for dietary supplement use and colorectal adenoma risk in individuals with Lynch syndrome were largely consistent with findings in the general population. Calcium supplement use might contribute to a lower risk of colorectal adenomas in the general population.…”

Efficacy of Vitamin C Supplements in Prevention of Cancer: A Meta-Analysis of Randomized Controlled Trials

“…The findings of our analysis were consistent with those of previous meta-analyses of RCTs, which concluded no association between vitamin C and prostate, colorectal, and gastrointestinal cancers. 9 10 23) Our findings, however, were inconsistent with those of previously published preclinical in vivo or in vitro studies on this issue. 24 25 26) In 2005, an in vitro experiment conducted by Abdel-Latif et al 27) suggested the efficacy of vitamin C supplements in facilitating apoptosis of esophageal cancer cells when used in conjunction with chemotherapy.…”

Dietary Total Antioxidant Capacity and Colorectal Cancer in the Italian EPIC Cohort

“…However, when colon and rectal cancers were considered separately, increasing TAC intake was associated with reducing risk of colon cancer and increasing risk of rectal cancer, both with significant trends. Intake of individual antioxidants (vitamin C, vitamin E and ß-carotene) was not significantly associated with colorectal cancer risk, in agreement with the 2007 WCRF/AICR panel report and recent reviews [ 15 , 16 , 28 ]. Thus, our evaluation of the total antioxidant capacity of the diet has found effects not revealed by investigation of individual antioxidants.…”

Correction: Dietary Supplement Use and Colorectal Adenoma Risk in Individuals with Lynch Syndrome: The GEOLynch Cohort Study

“…The association between dietary supplement use and sporadic colorectal adenoma risk in the general population has been investigated in many epidemiological studies. [23][24][25][26][27] Our findings for dietary supplement use and colorectal adenoma risk in individuals with Lynch syndrome were largely consistent with findings in the general population. Calcium supplement use might contribute to a lower risk of colorectal adenomas in the general population.…”