Association of choline and betaine levels with cancer incidence and survival: A meta-analysis

Abstract

Background & aims: Evidences suggest possible link between betaine and choline, methyl group donors, and cancer progression. We examined the association between choline and betaine levels and cancer incidence and survival in a meta-analysis of observational studies. Methods: We identified observational studies examining the association between choline and/or betaine levels from diet or blood and cancer incidence and survival by searching the PubMed and Web of Science databases for studies published up to Jan, 2018. After applying the selection criteria, 28 observational studies (9 case-control, 1 cross-sectional, and 18 cohort studies) were included. Relative risks (RRs) and 95% confidence intervals (CIs) were extracted, and combined RRs were calculated using random-effects models. Results: Choline levels were not associated with cancer incidence in a meta-analysis of cohort studies. Betaine levels reduced the risk of cancer incidence in a meta-analysis of cohort studies; combined relative risks (RRs) (95% CIs) comparing the top with the bottom categories were 0.93 (0.87-0.99). When we analyzed separately according to exposure assessment method, combined RRs (95% CIs) comparing the top with the bottom categories of betaine levels were 0.87 (95% CI: 0.78-0.95) for dietary betaine and 0.88 (95% CI: 0.77-0.99) for blood levels of betaine. There were no significant associations with cancer survivorship of choline or betaine levels. Conclusions: We concluded that high betaine levels were associated with lower risk of the cancer incidence, especially for colorectal cancer. (C) 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.