Dietary Choline and Betaine Are Not Associated With the Risk of Type 2 Diabetes. A Systematic Review and Meta-Analysis of Observational Studies

Sharifi-Zahabi E, Mohammadi S, Hajizadeh-Sharafabad F, Nasiri N, Sadeghi F, Saber A. Dietary Choline and Betaine Are Not Associated With the Risk of Type 2 Diabetes. A Systematic Review and Meta-Analysis of Observational Studies. J Diabetes Res. 2026 Jan 1;2026:9980163. doi: 10.1155/jdr/9980163.

https://pubmed.ncbi.nlm.nih.gov/41496893/

Background: The link between dietary choline/betaine and Type 2 diabetes (T2D) has been shown in several studies. However, the findings are controversial. This meta-analysis evaluated the connection between dietary choline/betaine and the incidence of T2D.

Methods: A thorough and organized search was conducted through PubMed, Scopus, and Web of Science up to September 2024. All reported effect sizes and their 95% CIs for risk of T2D were used to estimate log RRs with their standard errors (SEs). The overall combined effect size was obtained via a random effects model. The variability among the studies was examined using Cochrane's Q test and the I-squared statistic.

Results: A total of five studies, including 76,678 subjects, provided data on the relationship between dietary choline and T2D risk. Compared with the lowest category of dietary choline, the combined RR for the diabetes incidence was 1.15 (95% CI: 1.00, 1.33; p = 0.058; I 2 = 63.1%) for the highest category of dietary choline. The pooled analysis of three studies, with 65,725 subjects, indicated no significant link between dietary betaine and T2D incidence. Compared with the lowest category of dietary betaine, the combined RR for the diabetes incidence was 0.99 (95% CI: 0.90, 1.10; p = 0.871; I 2 = 58.1%). The certainty of the evidence was rated very low for choline intake and T2D incidence as well as betaine intake and T2D incidence, with a downgrade for risk of bias, inconsistency, imprecision, and indirectness.

Conclusion: The findings of this study do not advocate the role of dietary choline/betaine in T2D incidence. Due to the limited number of primary studies and high heterogeneities among them, more rigorously designed prospective studies are required to confirm our results.