Older Black adults who ate more whole grains appeared to have decreased memory loss as they aged, according to a study released Wednesday.
Researchers at RUSH University Medical Center, in Chicago, found an association among elderly Black residents who consumed more daily servings of whole grains – such as a slice of dark bread for one serving – with lower levels of memory decline. This equated to being more than eight years younger than those who ate smaller amounts of whole grain. The study, published in the American Academy of Neurology’s medical journal, showed a correlation, not causal evidence on whole grain.
The findings, scientists said, warrant further research into the effects of whole grain, which groups like the American Heart Association have associated with lower risks of diabetes, hypertension and stroke that disproportionately affect Black people. The study may also help health care providers identify diets to promote healthy aging. This can be particularly important for Black people, who are twice as likely to develop dementia compared to white people.
“In terms of dietary patterns, it is not really a one-size-fits-all approach,” Xiaoran Liu, a study author and a RUSH assistant professor of internal medicine, told USA TODAY. “We do have to honor the cultural differences in terms of their diet. Results from this study can help clinicians, physicians or dietitians to further tailoring that precise nutrition recommendation.”
Findings 'an interesting correlation'
The study was funded by the Alzheimer’s Association and the National Institutes of Health. It used responses from the Chicago Health and Aging Project, one of the few majority-Black aging cohorts that studied four South Side neighborhoods which ran from 1993 to 2012. The group surveyed more than 3,300 people, all older than 65 years old, for about six years.
Liu previously researched how a plant-based diet reduced cognitive decline, and she wanted to understand how whole grains may protect cognition as people age to curtail risks of Alzheimer’s and other dementia diseases that impair memory and thinking with everyday activities.
About 60% of participants were Black, though the study didn’t find similar trends of whole grain consumption reducing cognitive decline among white participants. The study divided participants into five groups based on whole grains eaten daily, from less than a fifth of a serving, to the highest group, at 2.7 servings. This is still less than federal dietary guidelines of three servings per day.
Black participants tended to consume more whole-grain foods – such as dark bread, cornbread or oats – and fewer refined grains, a processed form that removes a grain's nutrient-rich exteriors. Refined grains include white rice, pancakes and cold breakfast cereals. Compared to white participants, Black participants also consumed fewer calories and meat.
The participants filled out a 144-question survey about food tendencies every three years. Additionally, researchers conducted cognitive and memory tests that involved participants recalling words, remembering numbers, and ordering them. Researchers also accounted for other factors that may contribute to cognitive decline, such as age, sex, education and smoking.
The food questionnaire was self-reported, which researchers acknowledged was a limitation since people might not remember what they ate. The study accounted for recall bias by excluding participants who scored low in memory tests.
Despite inherent flaws with this type of study, it is standard practice in this field of research, according to researchers.
Richard King, MD, PhD, an associate professor of neurology at the University of Kentucky College of Medicine, said these studies are an important start, but it's important to keep expectations in context to understand higher rates of cognitive declines among African Americans and other vulnerable populations. Groups such as the Alzheimer's Association point to socioeconomic and health conditions that affect dementia risks for African Americans.
“There’s an interesting correlation,” King, who was unaffiliated with the study, said. “That might be enough to generate a hypothesis to motivate a clinical trial.”
Accounting for social-cultural backgrounds in medicine
Black people tend to have higher rates of cardiovascular diseases, which affect heart and blood vessels, that are linked to worse cognitive outcomes. Whole grains have been known to lower risk of cardiovascular diseases.
Yian Gu, MD, MS, PhD, an associate professor of neurological sciences at Columbia University Medical Center, said the study shows the need to account for social-cultural backgrounds to design dietary interventions to preserve cognition against Alzheimer’s disease. Gu, who was unaffiliated with the study, compared it to personalized medicine that looks at people’s genetic makeup to properly treat them.
“You need to take into account all the other factors when you design a prevention measure for populations,” she said.
'Probably not a magic bullet, either'
The study also builds on existing evidence about how whole grains reduce cognitive decline as people age.
Maya Vadiveloo, PhD, RD, an associate professor of nutrition at the University of Rhode Island, said whole grains are associated with better cognition because of fiber and polyphenols, as well as vitamins B and E, that provide antioxidants to reduce inflammation and oxidation that harm the body. Along with more whole grains, she pointed to overall dietary patterns, which include eating more nuts, seeds and legumes, to preserve cognition.
“Any change is better than no change,” Vadiveloo, another unaffiliated researcher, said. “It’s probably not a magic bullet, either.”
After a decade, the Chicago project, the cohort sampled in the study, restarted in 2021, expanding to Latino participants. Nonwhite groups need further study to tailor best approaches, researchers said.
“In a way, this is just an incremental field,” said study co-author Kuman Rajan, a RUSH medical center professor who runs the university’s aging center. “There is so much information suggesting that diet does play a very important role in reducing Alzheimer’s disease risk.”
Researchers plan to next look at how nutrients in whole grains may specifically contribute to protecting cognition.
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