For healthy middle-aged and older adults, adding cranberries to the diet may help improve memory and brain function, in addition to lowering LDL cholesterol, new research suggests.
Results from a randomized, placebo-controlled trial of adults aged 50-80 years showed that consuming freeze-dried cranberry extract, which is equal to one cup of fresh cranberries, for 12 weeks was associated with improved episodic memory. This coincided with increased blood flow to key areas of the brain that support cognition.
“This study reports for the first time the effect of long-term cranberry supplementation [as a] 12-week placebo-controlled intervention upon cognitive performance and brain health,” lead investigator David Vauzour, PhD, University of East Anglia Norwich Medical School, United Kingdom, told Medscape Medical News.
The findings were published online today in Frontiers of Nutrition.
Cranberries are particularly rich in (poly)phenols such as anthocyanins, proanthocyanidins (both A- and B-type), flavonols, and hydroxycinnamic acids. These compounds are known to have antioxidant and anti-inflammatory effects, and are recognized for their neuroprotective potential.
High-molecular-weight polyphenols such as proanthocyanidins also affect the gut microbiota and may improve cognition by modulating the gut-brain axis.
In the current study, 60 healthy adults (mean age, 65 years) consumed cranberry powder that was equivalent to 100 g of fresh cranberries or matching placebo for 12 weeks.
Before and after the intervention, all participants underwent a battery of cognitive tests in combination with comprehensive biochemical and neuroimaging assessments.
The total concentration of (poly)phenol metabolites in plasma increased by 1.82 μM in the cranberry group, with no increase observed in the placebo group.
At baseline, there were no significant differences in regional brain perfusion between the cranberry and placebo groups.
Mixed linear modeling controlling for age and education showed an increase in perfusion between baseline and follow-up in the cranberry group compared with a relative decrease in perfusion over time in the placebo group.
In the cranberry group, increased regional perfusion was observed in the right entorhinal cortex, the accumbens area, and the caudate. This was accompanied by significantly improved visual memory, as assessed by delayed recall on the Rey Complex Figure Test (P = .028).
However, the cranberry intervention did not improve other neurocognitive domains, such as working memory and executive functioning.
The cranberry group did show a significant decrease in LDL cholesterol levels, suggesting that cranberries can improve vascular health and may in part contribute to the improvement in brain perfusion and cognition, the investigators note.
Vauzour cautioned that the study focused only on healthy older adults.
“It is currently unknown whether such an effect may be translated to a clinical population of cognitively impaired adults in the context of neurodegenerative conditions such as mild cognitive impairment or dementia,” he said.
Key Message: Eat Natural Foods
Commenting on the study for Medscape Medical News, Zhaoping Li, MD, PhD, director of the Center for Human Nutrition and chief of the Division of Clinical Nutrition, David Geffen School of Medicine, University of California Los Angeles, said she was not surprised by the findings.
“Foods rich in phenolic compounds such as berries and other fruits have been shown to improve memory, especially visual memory. We have done a similar study with pomegranate with similar findings,” said Li, who was not involved with the research.
“The key message should be eating more natural foods such as fruits and vegetables to replace ultra processed foods will improve our overall health beyond memory,” she added.
Also commenting on the findings, Heather Snyder, PhD, vice president of medical and scientific relations at the Alzheimer’s Association said, “The opportunity to eat a balanced diet may contribute to decreasing one’s risk for cognitive decline and dementia.”
“However, to date, there is not one single ingredient that, through rigorous research, has been found to prevent or reduce risk of dementia,” Snyder told Medscape Medical News.
She added that “given the complexity of the brain and the diseases that cause dementia,” it is unlikely that just one food, ingredient, or supplement can have a significant effect against disease.
“For now, we recommend focusing on diet as a whole and incorporating many healthy foods (vegetables, fruits, lean proteins) into your diet,” Snyder said.
This study was supported by a grant from the Cranberry Institute. However, the organization was not involved in the design, implementation, analysis, or interpretation of the data. Vauzour, Li, and Snyder have disclosed no relevant financial relationships.
Front Nutr. Published online May 19, 2022. Full text
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