Vegetable intake and metabolic risk factors: A Mendelian randomization study

Background: The associations between vegetable intake and metabolic risk factors remain inconsistent. This study was aimed to investigate the association between cooked and raw vegetable intake with serum lipids, body mass index (BMI), blood pressure and glycemic traits. Methods: This was a two sample Mendelian randomization study. Nine and 19 genetic variants were identified from genome wide association studies (GWAS) as instrumental variables for cooked and raw vegetable intake. Summary level statistics were used from GWAS of total cholesterol, triglycerides, high density lipoprotein, low density lipoprotein, systolic blood pressure, diastolic blood pressure, BMI, fasting glucose, fasting insulin, glycated haemoglobin and 2 hour glucose after oral glucose tolerance test. Multivariable MR with inverse variance weighted method was performed as primary analysis, while median-based method and MR Egger method were performed as sensitivity analyses. Results: Vegetable intake was not associated with total cholesterol (-0.06 [-0.30, 0.18] and -0.02 [-0.20, 0.16] for each serving increase of cooked and raw vegetable intake) and triglyceride (-0.12 [-0.36, 0.13] and 0.03 [-0.15, 0.22]). Null evidence was observed for associations between vegetable intake and lipoproteins, blood pressure, BMI, insulin and glycemic measures. Sensitivity analyses generated similar null associations. Conclusions: We found null association between vegetable intake and metabolic risk factors. This is consistent with previous MR findings of null associations between diet-derived antioxidants and metabolic risk factors.