Breakfast Skipping Increases the Risk of Coronary Heart Disease and Myocardial Infarction: Evidence From the Mendelian Randomization Study

Observational studies have suggested a potential association between breakfast skipping and the risk of coronary heart disease (CHD) and myocardial infarction (MI). Nevertheless, due to potential confounders and reverse causation, the causal relationship remains unclear. This study aims to comprehensively assess the causal effect of breakfast skipping on CHD and MI through a two-sample Mendelian randomization (MR) analysis. Genome-wide summary statistics of breakfast skipping, CHD, and MI were obtained from public databases. Instrument variables (IVs) proxying for breakfast skipping were screened based on strict (p < 5e-8) and lenient (p < 1e-5) thresholds. Quality control of IVs was performed using Cochran's Q test, MR-Egger intercept test, and MR PRESSO global test. Inverse variance weighted (IVW) served as the primary MR method for assessing causal associations, while MR-Egger, weighted median, and maximum likelihood were used as supplementary methods. The effect of breakfast skipping on CHD and MI in both CARDIoGRAMplusC4D and FinnGen cohorts was assessed, and the results were integrated using meta-analysis. Quality control tests showed no heterogeneity or horizontal pleiotropy in IVs. After conducting a meta-analysis of the MR results from the IVW method under strict IV screening thresholds, breakfast skipping significantly increases the risk of CHD [odds ratio (OR) = 1.358, p = 3.95E-02] and MI (OR = 1.449, p = 4.17E-02). Similarly, meta-analysis of the IVW results under lenient IV screening thresholds also demonstrated the detrimental effects of breakfast skipping on CHD (OR = 1.198, p = 5.55E-03) and MI (OR = 1.378, p = 4.08E-05). Three other MR methods showed parallel results to IVW (OR > 1). Overall, the present study demonstrates that breakfast skipping significantly increases the risk of CHD and MI. Therefore, maintaining a high-quality breakfast intake can be considered an essential primary prevention measure for CHD and MI.