Antioxidant supplements for preventing gastrointestinal cancers

Abstract

We could not find convincing evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, antioxidant supplements seem to increase overall mortality. The potential cancer preventive effect of selenium should be tested in adequately conducted randomised trials.

Dietary factors and the risk of gastric and colorectal cancers: A Mendelian randomization study

“…Its potential protective effect against cancer development is supported by its antioxidant properties, which may help reduce the risk of gastric and colorectal cancers. [15,51] Our findings are consistent with this. Vitamin C also regulates the immune system, which may have implications for tumor immunity and immune response.…”

Dietary factors and the risk of gastric and colorectal cancers: A Mendelian randomization study

“…Its potential protective effect against cancer development is supported by its antioxidant properties, which may help reduce the risk of gastric and colorectal cancers. [15,51] Our findings are consistent with this. Vitamin C also regulates the immune system, which may have implications for tumor immunity and immune response.…”

Beta‐carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials

“…In the case of prostate cancer, since a borderline significant increased risk was observed for subjects with high baseline prostate specific antigen in the SU.VI.MAX trial,16 this effect deserves further investigation. We do not observe any reduction of lung, pancreatic or colorectal cancer risks with beta‐carotene supplementation, in agreement with results of recent metaanalyses on primary or secondary cancers 24–26…”

“…We did not find any significant effect of beta‐carotene supplementation on stomach cancer when all available studies were included in the metaanalysis, as described previously 26, 27. However, a significantly decreased risk was found in populations with a majority of women and with low‐dose beta‐carotene supplementation (RR, 0.84; p = 0.047 in both cases).…”

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

“…Other systematic reviews have also found that antioxidants did not reduce gastrointestinal cancer (oesophageal, gastric, small intestinal, colorectal, pancreatic, liver and biliary tract). Indeed, there is some evidence that β‐carotene and vitamin A might increase the risk [19] and that vitamin A, vitamin E and β‐carotene might furthermore increase overall mortality [42]. Despite three recent large RCTs [20–22], our findings are consistent with the previous reviews and make it even less likely that antioxidants are effective chemopreventive agents for colorectal cancer in the general population.…”

Dietary factors and the risk of gastric and colorectal cancers: A Mendelian randomization study

“…Its potential protective effect against cancer development is supported by its antioxidant properties, which may help reduce the risk of gastric and colorectal cancers. [15,51] Our findings are consistent with this. Vitamin C also regulates the immune system, which may have implications for tumor immunity and immune response.…”

Beta‐carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials

“…In the case of prostate cancer, since a borderline significant increased risk was observed for subjects with high baseline prostate specific antigen in the SU.VI.MAX trial,16 this effect deserves further investigation. We do not observe any reduction of lung, pancreatic or colorectal cancer risks with beta‐carotene supplementation, in agreement with results of recent metaanalyses on primary or secondary cancers 24–26…”

“…We did not find any significant effect of beta‐carotene supplementation on stomach cancer when all available studies were included in the metaanalysis, as described previously 26, 27. However, a significantly decreased risk was found in populations with a majority of women and with low‐dose beta‐carotene supplementation (RR, 0.84; p = 0.047 in both cases).…”

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

“…Other systematic reviews have also found that antioxidants did not reduce gastrointestinal cancer (oesophageal, gastric, small intestinal, colorectal, pancreatic, liver and biliary tract). Indeed, there is some evidence that β‐carotene and vitamin A might increase the risk [19] and that vitamin A, vitamin E and β‐carotene might furthermore increase overall mortality [42]. Despite three recent large RCTs [20–22], our findings are consistent with the previous reviews and make it even less likely that antioxidants are effective chemopreventive agents for colorectal cancer in the general population.…”

Dietary factors and the risk of gastric and colorectal cancers: A Mendelian randomization study

“…Its potential protective effect against cancer development is supported by its antioxidant properties, which may help reduce the risk of gastric and colorectal cancers. [15,51] Our findings are consistent with this. Vitamin C also regulates the immune system, which may have implications for tumor immunity and immune response.…”

Beta‐carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials

“…In the case of prostate cancer, since a borderline significant increased risk was observed for subjects with high baseline prostate specific antigen in the SU.VI.MAX trial,16 this effect deserves further investigation. We do not observe any reduction of lung, pancreatic or colorectal cancer risks with beta‐carotene supplementation, in agreement with results of recent metaanalyses on primary or secondary cancers 24–26…”

“…We did not find any significant effect of beta‐carotene supplementation on stomach cancer when all available studies were included in the metaanalysis, as described previously 26, 27. However, a significantly decreased risk was found in populations with a majority of women and with low‐dose beta‐carotene supplementation (RR, 0.84; p = 0.047 in both cases).…”

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

“…Other systematic reviews have also found that antioxidants did not reduce gastrointestinal cancer (oesophageal, gastric, small intestinal, colorectal, pancreatic, liver and biliary tract). Indeed, there is some evidence that β‐carotene and vitamin A might increase the risk [19] and that vitamin A, vitamin E and β‐carotene might furthermore increase overall mortality [42]. Despite three recent large RCTs [20–22], our findings are consistent with the previous reviews and make it even less likely that antioxidants are effective chemopreventive agents for colorectal cancer in the general population.…”