Supplementation with vitamin B may or may not reduce the risk of certain cancers, with varying effects depending on the type of cancer and vitamin B compounds, according to a study.
A team of investigators conducted a systematic review of randomized controlled trials, clinical trials, and case studies identified using the database of PubMed and following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses—Scoping Reviews guidelines.
Two reviewers independently screened titles, abstracts, and articles, while a third person resolved conflicts, before the included articles underwent data extraction and quality appraisal. The Covidence software was used to manage and track the data during the search process.
A total of 694 articles were identified, of which 25 were included in the review. Based on the assessment, vitamin supplementation had different effects on cancer risk.
Several studies reported the association of vitamin B supplementation with a reduced risk of cancer: B9 and B6 in nasopharyngeal carcinoma (n=1,200 patients) and in pancreatic cancer (n= 258 patients), B3 in hepatocellular carcinoma (n= 494,860 patients), B6 in breast cancer (n= 27,853 patients), and B9 in BRCA1-positive breast cancer (n=400 patients).
In contrast, other studies found that some B vitamin supplements contributed to an increased risk or negative outcomes of cancer: B6 during nasopharyngeal carcinoma treatment (n=592 patients), B6 in risk of hepatocellular carcinoma (n=494,860 patients), and B9 plasma levels in breast cancer (n=164 patients).
“Due to the many adverse effects that occur in cancer treatment, the effectiveness of vitamin B supplementation in alleviating adverse effects was evaluated,” the investigators said.
Specifically, two studies found that vitamin B6 and B12 supplementation plus acupuncture were effective as adjunct therapies for reducing chemotherapy-induced peripheral neuropathy in 23 and 104 patients, respectively. However, no significant findings were noted with regard to vitamin B supplementation in patients with chemotherapy-induced hand-foot syndrome.