- Researchers examined the effects of nut consumption on memory and brain health.
- They found that consuming 60 grams of mixed nuts per day increases verbal memory and blood flow in the brain.
- Further studies are needed to confirm the results.
Nuts are common to both of these diets. Nuts contain nutrients, including unsaturated fatty acids, proteins, and polyphenols, which may all benefit cognition.
Further study of how nuts impact cognition and brain health could inform dietary and public health recommendations.
Recently, researchers investigated the effects of daily nut consumption on cognition and brain health. They found that daily nut consumption benefitted blood flow in the brain and verbal memory in older adults.
The study was published in Clinical Nutrition and was funded by the International Nuts and Dried Fruit Council (INC).
For the study, the researchers recruited 28 healthy individuals at an average age of 65 years, and an average body mass index (BMI) of 27.9. A BMI between 25 and 29.9 is considered overweight.
The participants were randomized into two groups and assigned one of two diet plans for 16 weeks. One group consumed 60 grams of walnuts, pistachios, cashews, and hazelnuts per day, while the other group consumed no nuts. The groups switched nut consumption protocols after an 8-week washout period.
At the end of each period, the researchers gathered indicators of participants’:
- brain vascular function
- endothelial function — key for blood clotting and the passage of fluids and electrolytes from the blood into tissues
- arterial stiffness
- retinal microvasculature
- cognitive performance.
Ultimately, they found that daily nut consumption increased blood flow in various brain areas, including the left frontal lobe, the bilateral prefrontal cortex, and the frontal lobe.
They also found that nut consumption improved peripheral endothelial function, reduced arterial stiffness, and improved retinal microvasculature.
Additionally, after consuming nuts, participants were able to remember 16% more words in a verbal memory task. Nut consumption, however, provided no difference in other areas, including executive function, stress, and quality of life.
Medical News Today spoke with Dana Hunnes, PhD, a senior clinical dietitian at the UCLA Medical Center and an assistant professor at the UCLA Fielding School of Public Health in Los Angeles, not involved in the study, about how nut consumption may improve memory and brain health.
She noted that the exact mechanisms are unknown. However, she added that the researchers suggested that nut consumption keeps blood vessels in the brain healthy, possibly by lowering inflammation which is linked to lower cognitive function and conditions such as Alzheimer’s disease.
Dani Felber, an integrative brain health dietitian and owner of Focused Nutrition and Wellness, not involved in the study, also told MNT:
“Our brains are particularly susceptible to oxidative stress, which damages our brain cells over time, leading to a decline in memory and cognitive function. While cognitive decline is a normal part of the aging process, slower rates of cognitive decline are associated with a higher intake of antioxidants, which are vital for reducing oxidative stress. Nuts, particularly walnuts and pecans, have significant levels of antioxidants, even higher than blueberries, which are famous for their high antioxidant levels.”
Dr. Hunnes said that the short length of the study means the long-term effects of nut consumption on memory and cognitive health remain unknown.
“Memory and cognitive function is a long-term and long-to-develop issue, [meaning] it takes more than just 16 weeks [to reach conclusions],” she noted.
“As always in nutrition, it adds to the literature and continues to show positive effects of eating healthy foods like nuts, but as always, longer-term studies are needed,” she added.
MNT also spoke with Dr. Debbie Fetter, assistant professor of teaching in nutrition at the University of California, Davis, who was not involved in the study, about its limitations.
She said: “The study inclusionary criteria had a particular BMI range, which recruited individuals who fell in the overweight to obese range. However, BMI only captures the ratio of height to weight, which leaves out a lot of information when it comes to assessing someone’s body composition.”
When asked which nuts are most beneficial for brain health, Felber said:
“Walnuts, which fittingly resemble little brains, are considered one of best nuts for brain health for a number of reasons. On top of being the only nuts to contain a significant amount of omega-3 fatty acids, walnuts boast the highest content of antioxidants, as well as the highest potency, or quality, of antioxidants, relative to other common nuts.”
Other nuts for brain health include:
MNT also asked Dr. Hunnes what food alternatives may confer similar benefits for those allergic to nuts.
“It’s possible that olives, soybeans, and seeds — such as sunflower, chia, or flax — would have similar positive health benefits since they all have healthy levels of monounsaturated and polyunsaturated omega-3 oils,” she said.
Dr. Fetter agreed, noting that “[s]eeds can be a great option because they also contain a similar profile of nutrients.”
“However,” she cautioned, “sesame is also a major allergen and almost half of people who have food allergies have allergies to multiple foods.”
“Beans and legumes are [also] a great source of plant protein, fiber, essential vitamins and minerals, and polyphenols. Drizzle in some olive oil to add healthful fats,” Dr. Fetter added.
Like Dr. Hunnes, Dr. Fetter also emphasized the benefits of omega-3 fatty acids for brain health. “Fatty fish, like salmon and tuna, are great sources of the essential fat omega-3,” she said, noting that “[o]mega-3 fatty acids play key roles in the brain, heart, immune system, and metabolism.”