Youn J, et al. - The association between choline and betaine levels from diet or blood with the cancer incidence and survival was determined using PubMed and Web of Science databases. The relative risks (RRs) and 95% confidence intervals (CIs) were extracted, and combined RRs were estimated via random-effects models. It was observed that the choline levels were not related to cancer incidence. Especially in the case colorectal cancer, high betaine levels demonstrated a connection with a lower risk of the cancer incidence. In terms of cancer survival, no prominent correlations were discovered with the choline or betaine levels.