A new Chinese study explored the association between serum levels of B vitamins and gastrointestinal cancers. Vitamins B2 and B12, and higher levels of the B2 metabolite flavin mononucleotide, were associated with decreased risk of oesophageal squamous cell carcinomas.
The various forms of Vitamin B are heavily involved in the production, maintenance, and regulation of DNA – the blueprint cells read in order to make the molecules necessary to carry out their functions. Impairing any of these DNA-related processes can greatly disrupt cellular processes and ultimately lead to cancer. As such, associations between Vitamin B deficiencies and the risk of developing several types of cancer have been explored. Little research, however, has explored the relationship between levels of B vitamins and gastrointestinal cancers, especially those of the throat and stomach.
A 2016 study published in Scientific Reports tested the association between baseline concentrations of B Vitamins and the risk of oesophageal squamous cell carcinoma (OSCC), a form of throat cancer, and gastric cardia adenocarcinoma (GCA), a form of stomach cancer. Participants were chosen from among subjects of the Linxian General Population Nutrition Interval Trial (NIT), conducted between 1985 and 1991. In the NIT, 29,584 adults aged 40-69 from Linxian, China – an area with persistent malnutrition and very high rates of OSCC and GCA – were given dietary supplements or a placebo and assessed for rates of OSCC, GCA, cancer-related and overall deaths. By the conclusion of the NIT, there were 640 cases of OSCC and 435 cases of GCA.
The supplement groups were administered various doses of vitamins and minerals in combination. Roughly half the participants were administered a combination including 3.2mg of riboflavin (Vitamin B2) and 40mg of niacin (Vitamin B3), called Factor B by the NIT researchers. Blood was drawn from each subject before they were administered a supplement or placebo, and was kept frozen for later analysis. In 1996, levels of Vitamins B2, B6, B9, and B12, and flavin mononucleotide (FMN) – a product of B2 metabolism – were measured for each blood sample.
For the 2016 study, 498 of the OSCC and 255 of the GCA cases were randomly selected, and a random sample of 947 NIT participants, with or without OSCC or GCA, was designated the control group for comparison. (These numbers were chosen to produce a sample size appropriate for the analyses conducted.) Cases were matched with controls and data was analyzed with respect to age at the start of the NIT (< 50, 50-60, or >60), sex, cigarette smoking, alcohol consumption, body mass index (BMI), and assignment to a Factor B-containing group.
Vitamin B2 was associated with a lower risk of OSCC. This association was stronger in women than in men, and in those >60 compared to other age groups. Overall, the prevalence of OSCC among those with the highest levels was 44% lower than that of the 25th percentile: for those assigned to a Factor B-containing group the prevalence was 40% lower, and for those who were not, the prevalence was 49% lower. B2 was also associated with a decreased risk of GCA in those 50 or older. Participants in the 50th and 75th percentiles for B6 levels were 40% and 47% more likely to have OSCC than those in the 25th percentile, respectively. Vitamin B9 was associated with an increased risk of GCA, though this association was not found to be significant when Factor B status was taken into account. Those with higher B9 levels in Factor B groups had a slightly higher prevalence of OSCC overall. Vitamin B12 was associated with a slightly decreased risk of OSCC. FMN was associated with an increased risk of OSCC in participants assigned to a Factor B group.
The study findings suggest that Vitamin B2 significantly decreases OSCC risk, as well as GCA risk in those 50 or older. Moreover, FMN and mid-to-high levels of B6 may raise OSCC risk. As Factor B status modified the risk of OSCC and GCA in several cases, exploring the interplay between different B vitamins in combination may help determine their contributions to the development of these cancers. Further, as the B2 derivative FMN had the opposite effect on OSCC risk as B2, the role of B Vitamins’ metabolites and alternate forms on cancer risk may also warrant study. As blood samples were only collected at baseline, supplementation may have had a significant impact on cancer risk. The study was conducted among a chronically malnourished population, and as such, further research may be required to determine the applicability of these findings to well-fed groups. Further research into the effects of the other B vitamins – B1, B3, B5, and B7 – on the risk of developing OSCC, GCA, and other gastrointestinal cancers would be beneficial for the development of diet-related cancer-prevention strategies.
Written By: Raishard Haynes, MBS