Eating almonds daily may have neuroprotective effects in people at risk of developing diabetes, according to a recent clinical trial. Researchers found that incorporating these nuts into a balanced diet improved processing speed and executive function in adults with slightly elevated blood sugar levels. The results of this study were published in The Journal of Nutrition.
Prediabetes is a condition in which blood sugar levels are chronically higher than normal, but not yet high enough to be officially diagnosed as type 2 diabetes. This metabolic condition often involves a biological mechanism known as insulin resistance. When a person has insulin resistance, cells in the body do not respond properly to the hormone insulin. Because of this resistance, cells have a hard time properly removing floating glucose from the bloodstream, leading to elevated blood sugar levels.
Over time, this subtle metabolic dysfunction can cause systemic physical stress. The main result is a low-grade inflammation accompanied by a process called oxidative stress. Oxidative stress occurs when there is a severe imbalance between unstable molecules called free radicals and the body’s antioxidant defenses. When the number of free radicals exceeds the number of antioxidants, they begin to attack healthy tissue, eventually causing cell damage.
Medical researchers suspect that these early metabolic disorders may not only tax the cardiovascular system. It can also actively deprive the brain of needed metabolic support. The human brain uses enormous amounts of energy, and its neurons require stable and predictable pathways to process glucose. When insulin signaling is disrupted, the brain can struggle to maintain structural integrity and processing capacity.
Previous observational data from large public health databases point to an association between insulin resistance and early deficits in cognitive performance. One area that is often affected is executive function. Executive function functions as the brain’s internal management system. It controls important daily tasks such as organizing schedules, retaining information in working memory, focusing attention, and manipulating multiple streams of spatial information.
Seema Gulati, a researcher at the Diabetes Foundation in New Delhi, India, led a scientific study to examine whether certain dietary interventions can help protect memory and processing speed in high-risk populations. The research team focused entirely on middle-aged Asian Indians with undiagnosed prediabetes. India currently has a very high rate of undiagnosed prediabetes, putting millions of adults at risk of both cardiovascular disease and cognitive decline as they age.
Scientists decided to test almonds. This is because these nuts are widely consumed in India and are naturally rich in protective nutrients. Almonds are rich in vitamin E, unsaturated fats, dietary fiber, and protective plant compounds called polyphenols. Previous nutritional research suggests that these antioxidant-rich ingredients may help protect neural pathways by reducing inflammation and preventing postprandial blood sugar spikes.
To test this hypothesis, Gulati and colleagues organized a 6-month randomized controlled trial at a medical center in New Delhi. They recruited 60 adults between the ages of 40 and 60 who specifically met clinical criteria for prediabetes. The research team divided the participants into two groups and compared their long-term health.
One group served as a control and received standard diet and exercise counseling aligned with local dietary guidelines. The intervention group received the exact same health instructions, but also included a daily serving of raw, unroasted almonds in their daily routine. Almonds are calculated to provide approximately 20 percent of each individual’s daily energy needs, which equates to approximately 30 to 40 grams of nuts per day.
To balance their overall daily energy intake, participants in the almond group were advised to make changes to their typical diet. They were instructed to replace some visible cooking fats and carbohydrate-rich cereals with the inherent fat found in almonds. Healthcare workers called participants periodically and checked empty almond wrappers to ensure people were actually following dietary protocols.
The researchers measured brain function at the beginning of the study and again after 24 weeks. They utilized a standardized tablet-based neuropsychological assessment to assess how well participants performed on various mental tasks. These digital tests required participants to touch a screen to match complex patterns, follow visual cues, and complete spatial alignments. The software tracked its accuracy and response time down to the millisecond.
Medical professionals also collected blood samples from participants to track changes in blood sugar levels, insulin production, and inflammatory markers. They specifically looked for proteins synthesized in the liver that indicate systemic inflammation. Additionally, the research team measured plasma alpha-tocopherol. This is a specific form of vitamin E that acts as a reliable marker of how well your body is absorbing nutrients from almonds.
To measure cellular stress, the researchers tested for certain biological byproducts in the blood that indicate the presence of ongoing oxidative stress. When free radicals attack fat molecules in cell membranes, they form a trail of biological debris known as lipid peroxidation. By measuring the levels of these debris, the scientific team was able to verify whether the antioxidant properties of almonds were actually working in the body.
By the end of the six-month period, the researchers observed clear cognitive differences in the group that consumed almonds. These participants showed significantly better performance on tasks requiring executive function when compared to the control group. They demonstrated an improved ability to plan spatial sequence tasks and solve visual problems in fewer trials.
The almond group also had faster overall processing speed. They responded more quickly to visual stimuli during attention training using a tablet. In the control group, these corresponding cognitive improvements were not seen over the same physical follow-up period.
These brain-based benefits were accompanied by measurable biological changes. Participants who ate almonds experienced lower fasting blood sugar levels. They also lost slightly more weight, lost several inches in waist circumference, and showed improved body metrics than those in the control group.
Blood analysis revealed that the almond group had much higher levels of the antioxidant vitamin E by the end of the study. At the same time, markers of lipid peroxidation were also reduced. Researchers theorized that the polyphenols and vitamin E provided by almonds may help neutralize harmful free radicals circulating in the body.
By reducing the overall oxidative load and smoothing the postprandial rise in blood glucose levels, the dietary changes provided the brain with a more stable metabolic environment. Raw nuts have a low glycemic index, so their high fat and protein content slows down digestion and prevents the release of large amounts of glucose into the bloodstream. This slow digestive process may protect delicate blood vessels in the brain from damage caused by normally unstable sugar fluctuations.
Although the biological measurements directly match scores on cognitive tests, the test has several limitations that scientists need to address in future studies. This study followed 60 participants, which represents a moderate sample size that would require replication in a targeted manner. Additionally, 24 weeks is a relatively short period of time when studying a biological process as gradual as age-related cognitive decline.
The researchers did not measure changes in specific brain-derived proteins or brain-healthy fatty acids such as omega-3s, which could have provided a more detailed picture of the neurological mechanisms at play. The daily intake of almonds is fixed at 20% of daily energy, and it is unclear whether the same results can be achieved with a lower amount of nuts.
Future studies will need to follow participants for several consecutive years to see whether these dietary habits actually slow the onset of dementia and Alzheimer’s disease in vulnerable populations. Examining diverse populations beyond South Asia will also help researchers understand whether these neurological benefits also apply to different genetic backgrounds and dietary preferences.
The study, “Effect of 24 weeks of almond supplementation on executive function and processing speed in middle-aged Asian Indians with prediabetes: an open-label randomized controlled trial,” was authored by Seema Gulati, Anoop Misra, Rajneesh Tiwari, Ravindra M Pandey, and Meenu Sharma.
