Can Vitamins Help Prevent Gastric Cancer?
Vitamins are essential for health. In the United States many individuals do not meet the daily requirements for vitamins. According to Frei and colleagues over 93% of adults do not meet the estimated average requirements for Vitamins D and E, 50% do not meet recommended intakes for vitamin A and C and 71% do not get enough vitamin K from diet alone. Fortified foods and dietary supplements can help bridge nutrient gaps. The benefits of vitamin (and mineral) supplementation on disease endpoints is less clear. A prominent review reported null associations between vitamin and mineral supplements for cardiovascular disease or cancer prevention. However, the interpretation of the review was severely limited because data from studies of various supplements and wide ranging doses was pooled.
More recently, Kong and colleagues examined the association between vitamin intake and gastric cancer using data from 47 randomized trials and observational studies comprising over 1.2 million subjects. The large size of the study uniquely facilitated analysis of total vitamin intake, as well as different doses of individual vitamins with respect to subsequent risk of developing gastric cancer.
Overall the risk of developing gastric cancer was 22% lower in people with the highest vitamin intake versus the lowest vitamin intake. High doses of vitamins above the tolerable upper limit had no effect on gastric cancer risk. Conversely, risk was 24% lower in individuals who received doses below the upper limit. The authors additionally identified doses of Vitamin A (1.5mg/day), Vitamin C (100mg/day) and Vitamin E (10mg/day) that were significantly associated with reduced gastric cancer risk. This importantly shows the potential benefit of low doses of vitamins and provides guidance for the design of future intervention studies.
Bottom line: There is compelling evidence that vitamins may reduce the risk of gastric cancer but individuals should supplement responsibly, and be aware of other non-diet risk factors.
Kong P et al. Vitamin intake reduce the risk of gastric cancer: meta-analysis and systematic review of randomized and observational studies. PLoS One 2014, doi:10.1371/journal.pone.0116060
Frei B et al. Comments and Responses: Enough is Enough. Ann Intern Med 2014, doi:10.7326/L14-5011
Fulgoni VL III et al. Foods, fortificants and supplements : Where do Americans get their nutrients ? J Nutr 2011, doi:10.3945/jn.111.142257
Fortmann et al. Vitamin and mineral supplements in the primary prevention of cardiovascular disease and cancer: an updated systematic evidence review for the U.S. Preventive Services Task Force. Ann Intern Med 2013, doi:10.7326/0003-4819-159-12-201312170-00729