Plant-based diet may help delay cognitive deterioration among Black adults, study finds

07 Mar 2022 --- Consuming a plant-based diet can significantly delay the pace of cognitive deterioration among older Black adults in the US. The same dietary pattern had less impact on cognitive impairment in older white adults.

This is the conclusion of an American Heart Association preliminary study that unveiled overall cognitive deterioration reduced by 28.4% among Black people who had the healthiest diets.

According to the American Heart Association, healthy dietary adjustments have been shown to prevent cognitive decline in previous studies. However, there has been little research on the impact on Black adults, who have about double the risk of dementia as white adults.

“It’s not that the diet doesn’t work on white people. It just had a greater impact on African Americans,” says Xiaoran Liu, lead researcher and assistant professor at Rush University Medical Center’s Institute for Healthy Aging in Chicago.

“Science is coming out to support the importance of a healthy plant-based diet,” adds Maya Vadiveloo, assistant professor of nutrition at the University of Rhode Island.

“It doesn’t mean we can’t have any animal-sourced foods or low-fat dairy, but people should focus on eating more legumes and whole grains. These plant-based foods are essential for our overall health.”

In other studies, a primarily plant-based diet has also been associated with a lower incidence of stroke, heart disease and Type 2 diabetes. Until comprehensive research is published in a peer-reviewed journal, the findings are considered preliminary.

Analyzing different dietary patterns
During the decade-long study, researchers examined the nutrition and cognitive function of 4,753 Black and white adults with an average age of 74. The researchers used tests to assess overall cognition, perceptual speed and episodic memory, which is the capacity to recall personal experiences associated with a specific time and location.

The data revealed that the healthiest plant-based diet for Black adults delayed the loss in all three areas more than for white adults.The study findings emphasize the importance of eating various fruits and vegetables, whole grains, fish and seafood.

The participants were divided into three groups based on their scores from self-reported dietary patterns. The first group consisted of a healthy plant-based diet rich in fruits, vegetables, nuts, whole grains, legumes, vegetable oils, tea and coffee. 

The second group were the participants who ate a less-healthy plant-based diet rich in fruit juices, refined grains, potatoes, sugar-sweetened beverages and sweets. The third group ate a diet rich in animal fats, dairy, eggs, meats, fish or seafood.

Plant-based diets and cognitive decline
Compared to their Black contemporaries who ate a less healthy plant-based diet, overall cognitive deterioration reduced by 28.4% among Black people in the highest bracket of the healthiest eating group.

Overall cognitive deterioration was not slowed in either Black or white adults in the other two dietary categories.

For Black people, the effect of diet on perceptual speed and episodic memory was considerably more striking. Those who ate the healthiest plant-based diet had a 49.3% slower reduction in perceptual speed and a 44.2% slower decline in episodic memory than those who ate a more animal-based diet. 

Explaining the disparity in findings
There could be many explanations for the disparity between white and Black adults, Liu adds.

One reason could be that Black adults have a higher risk of cardiovascular problems, which affect cognitive health, so lowering their risk by eating a heart-healthy, plant-based diet could have a more significant impact on their brain health than people with a lower risk.

The gap in cognitive deterioration in the study, according to Liu, could be due to eating habits. Black adults, for example, consumed far more whole grains than white adults. Liu is currently looking at the effects of different food groups on the cognitive decline of participants.

For various reasons, Black individuals in the US suffer increased cardiovascular risks, including systemic and societal concerns that have historically limited access to care, medicines, nutritious meals and other risk-reducing options.

The need for increased diversity in nutrition guidelines and studies is apparent in industry. Previously, the US National Institutes of Health observed a lack of diversity in populations involved in precision nutrition research studies.

Also, APC Microbiome Ireland noted that individual ethnicity must be considered in microbiome-based diagnoses and therapies.

By Nicole Kerr