Abstract
Consumption of whole grains is associated with a reduction in chronic diseases and offers benefits for cardiovascular health and metabolic regulation. The relationship between whole grain corn and corn bran with the gut microbiota (GM) remains an area of growing interest, particularly regarding their influence on cardio-metabolic health.
To investigate the effects of different corn flours on cardio-metabolic outcomes and GM changes in adults with elevated low-density lipoprotein cholesterol (LDL-c) concentrations.
In this crossover study, 36 adults with LDL-c above 110 mg/dL consumed 48 g/day of three corn flour types for four weeks: whole-grain corn meal (WCM), refined corn meal (RCM), and a blend of RCM and corn bran (RCM+B). We assessed the impact on cardio-metabolic markers (LDL-c, high-density lipoprotein cholesterol [HDL-c], total cholesterol [TC], and triglycerides [TG]) and GM composition and estimated function. Statistical analyses included mixed-effects modeling and responder (> 5% decrease in LDL-c) analysis to evaluate changes in GM related to lipid profile improvements.
Of the three corn flour types, only RCM+B significantly decreased LDL-c over time (-10.4±3.6 mg/dL, P = 0.005) and marginally decreased TC (-9.2±3.9, P = 0.072) over time. There were no significant effects on HDL-c or TG concentrations. No significant changes were observed in GM alpha diversity, while beta diversity metrics indicated individual variability. Two genera, unclassified Lachnospiraceae and Agathobaculum (Padj ≤ 0.096), differed significantly by treatment, but only Agathobaculum remained significantly elevated in the WCM, compared to RCM and RCM+B, after adjustment for multiple comparisons.
The type of corn flour, particularly RCM+B, notably influenced LDL-c concentrations in adults with elevated LDL-c. This study suggests that incorporating milled fractions (e.g. bran) of whole grain corn with refined corn flour may be a viable alternative to supplementing manufactured grain products with isolated or synthetic fibers for improved metabolic health.
ClinicalTrials.gov ID: NCT03967990