New clinical research links refined cornmeal flour and corn bran mix to better heart health

08 Aug 2024 --- Switching from refined corn flour to a version with corn bran reduced low-density lipoprotein (LDL) cholesterol by 5% to 13.3% in a four-week randomized crossover clinical trial. The researchers reported these changes in 70% of the study’s participants, all of whom entered the trial with mild to moderately elevated LDL cholesterol. 

The study compared the impact of whole grain cornmeal, refined cornmeal and a blend of refined cornmeal with corn bran. The team found no changes in LDL or total cholesterol levels for the other two types of corn flour. 

“People often think that dietary changes must be robust and significant to have a real impact on cardiovascular health and metabolic regulation,” says Dr. Corrie Whisner, lead researcher and associate professor in the College of Health Solutions at Arizona State University, US. 

“The bottom line is this — corn is unique and underappreciated. The art and science of refining grains and making full use of corn bran can result in delicious foods that, in this case, also happen to produce real results for heart health.”

Realistic intervention 
The study, published in The Journal of Nutrition and partially funded by the Corn Division of the North American Millers’ Association, included 36 male and female participants. Despite their elevated levels, they were not taking cholesterol-lowering medications during the trial. They consumed all three flour types studied for four weeks each, with a two-week washout period in between interventions to return to baseline.

Participants received baked goods (muffins and pita bread) so the researchers could control the type and quality of corn flour consumed. The study participants did not change their grain food intake during the intervention. These products were developed by a master baker familiar with food formulation techniques and specialty ingredients used in foods commonly found in grocery stores. 

Participants received 10 pita breads and four corn muffins weekly, to replace wheat, oats and other grain-rich products.The researchers intentionally created a realistic intervention that could be “easily folded into a regular diet.” They aimed to illustrate the practicality of regularly incorporating foods made with corn bran-enriched flour into a heart-healthy diet pattern. 

A study published earlier this year also focused on lowering cholesterol in real-world research. Study participants substituted meat and fish with mycoprotein over four weeks, reducing their LDL cholesterol by 10% and non-high-density lipoprotein cholesterol by 6%. 

The team found no significant effects on high-density lipoprotein cholesterol or triglyceride concentrations. 

Gut microbiota impact 
The researchers also assessed participants’ gut microbiota composition and estimated function. However, they found no significant or consistent changes to gut microbiota diversity, and study participants reported no digestive discomforts or changes during the interventions. 

Two genera, unclassified Lachnospiraceae and Agathobaculum, differed significantly by treatment. During the whole grain cornmeal phase, researchers identified an increase in Agathobaculum, a common bacterium in the gut microbiota. However, they did not see this change in the other two phases. 

“The increase in Agathobaculum could be due to the greater diversity of polyphenols found in whole grain corn, which has the highest antioxidant capacity (compared to wheat, oats and rice), but the study did not analyze this possibility,” notes Whisner. 

“Nevertheless, while the influence of whole grains on the microbiota varies from person to person, some universals are generally known: fibers in whole grains can be fermented by microbes into butyrate, and fiber and butyrate are frequently associated with a healthy gut. These findings support that understanding.”

Last year, Nutrition Insight met with researchers who detailed the nutritional quality of sorghum bran. This bran contains higher levels of crude protein, fat, fiber, essential amino acids and minerals than whole grain or dehulled flour.