Bran-Enriched Corn Flour Reduces LDL Cholesterol in Adults with Elevated Levels, claims study

It is already known that whole grains have many health-promoting benefits, which lower the risks for chronic diseases: it reduces the risk of cardiovascular disease, diabetes, and cancer. The health benefits of whole grains have been observed because they are rich in dietary fiber and bioactive compounds like polyphenols. Foods made from whole wheat have vastly been studied, while other grains, such as corn, have not been put into the limelight as much, even though corn contains almost the same amount of fiber as wheat. Present in corn are metabolites of hemicellulose, cellulose, arabinoxylan, and ferulic acid; these all reduce LDL cholesterol. The mechanisms by which corn influences cardiometabolic health and gut microbiota remain poorly understood and, therefore, warrant additional research.

The subjects were healthy men and women between the ages of 18 to 70 years, whose mildly to moderately elevated LDL cholesterol levels ranged from ≥110 mg/dl. Inclusion of those individuals with LDL cholesterol above 190 mg/dL required physician clearance. People who had recent weight changes, special diets, food allergies, recent antibiotic use, or those with certain medical conditions, such as those on lipid-lowering medications, were excluded in this study. In addition, pregnant or lactating women were not eligible for this study. The eligible participants were prescreened, followed by fasting blood tests and the collection of informed consent, baseline health data, and fecal samples for gut microbiota analysis.

Participants ingested 48 g/d of whole-grain corn meal (WCM), refined corn meal with bran (RCM + B), or refined corn meal (RCM) for four weeks with two-week washout periods between each phase. Participants added corn-based foods to the diet in the form of muffins and pita bread and replaced other grain products in their diet. Compliance, gastrointestinal symptoms and dietary intake were monitored throughout. Blood lipids were determined by auto-analyzers, while stool samples were processed for sequencing of the microbiota. Mixed-effects modeling, Analysis of Variance (ANOVA), and permutational multivariate ANOVA (PERMANOVA) were conducted in the analysis of data.

Key Findings

• The RCM + B significantly reduced LDL cholesterol by about 10 mg/dL over time.

• Approximately 70% of individuals' reductions were larger than 5%.

• This was not reflected for WCM or RCM, underlining the additional benefit of bran in a cholesterol-reducing effect.

• There were no significant treatment, time, or period main effects for total cholesterol across the groups despite the reduction in LDL cholesterol.

• A significant difference in high density lipoprotein cholesterol wasobserved between WCM and RCM + B although there were no differences between WCM and RCM or RCM + B and RCM.

• The gut microbiota composition analysis did not show an alteration of any α or β diversity metrics between the different treatments. In contrast, differential abundance analysis showed an increased Agathobaculum in WCM compared to RCM. The increase was independent of cholesterol reduction. Compliance of participants was above 95% for all treatment groups. The gastrointestinal symptoms, stool characteristics, and product satisfaction did not differ across the treated groups.

• Testing their reception of corn-based products, offering many opportunities for its consumption, pita and muffins were best served and seen as "good" in terms of appearance, texture, flavour, and satisfaction.

The study gives insight into the effects of different types of corn flour on cardiometabolic outcomes and gut microbiota in adults with high LDL cholesterol. In particular, the corn bran-enriched meal appeared to be rather effective, showing high reductions in LDL cholesterol levels in most participants. This therefore could be an indication that adding bran to corn products might be a very practical means of improving cholesterol profiles and reducing cardiovascular risk.

Although the study did not show changes in total cholesterol and gut microbiota diversity, the targeted reduction in LDL using RCM + B supports its potential as a dietary intervention for the management of high cholesterol. Minimal changes in gut microbiota suggest that while the corn products influence cholesterol, they likely do not grossly perturb the gut ecosystem in the short term.

The current randomized crossover study demonstrated that the consumption of 48 g/day of corn meal enriched with bran significantly decreased LDL cholesterol in adults with high cholesterol and that 70% of the participants had reductions greater than 5%. The results support the recommendation for corn bran-enriched corn products as part of cholesterol-lowering diets and as easily accessible dietary solutions for individuals seeking to lower the risk for cardiometabolic diseases. Further research will be needed to catch the whole spectrum of long-term benefits and mechanisms behind these effects.

Reference:

Liedike, B., Khatib, M., Tabarsi, B., et al. (2024). Evaluating the Effects of Corn Flour Product Consumption on Cardiometabolic Outcomes and the Gut Microbiota in Adults with Elevated Cholesterol: A Randomized Crossover. The Journal of Nutrition. doi:10.1016/j.tjnut.2024.06.003.