Brain boost from pecans? New study finds short-term cognitive benefits

A recent study found that consumption of a pecan-enriched shake improved the cognitive performance of study participants compared to their performance after consuming a shake high in saturated fats. Participants performed better after the pecan-enriched shake on 8 out of 23 cognitive tests, though there were 3 tests where they performed better after the saturated fat shake. The paper was published in Nutritional Neuroscience.

Pecan is a type of tree nut that comes from the Carya illinoinensis tree, which is native to North America. The nuts are known for their rich, buttery flavor and are commonly used in baking, especially in pies and desserts. Pecans are a good source of healthy fats, fiber, and essential nutrients like manganese, thiamin, and zinc. They are also high in antioxidants, which help protect the body from cellular damage.

Pecans grow inside a hard shell that must be cracked open to access the edible kernel. The trees require a warm climate and several years to mature before they start producing nuts. In the United States, pecans are primarily grown in southern states, particularly Georgia, Texas, and New Mexico. Aside from culinary uses, pecan wood is also valued for furniture and for smoking meats.

Study author Alyssa J. Guadagni and her colleagues note that pecans contain the highest total polyphenol content of any tree nut. Polyphenols are naturally occurring compounds with antioxidant properties that may help protect against inflammation, heart disease, and certain cancers. Previous studies have suggested that polyphenols might also support cognitive performance, for example by preventing a post-meal dip in mental function.

To test the cognitive effects of pecan consumption, the researchers recruited 31 healthy adults between 18 and 30 years old. Sixteen of them were men. Each participant completed two study visits at the researchers’ lab.

For 24 hours before each visit, participants followed a controlled diet consisting of 50–55% carbohydrates, 15–20% protein, and 25–30% fat, and were instructed to avoid foods high in polyphenols. The researchers provided a list of such foods to avoid, as well as a sample meal plan for breakfast and lunch that adhered to the prescribed macronutrient ratios.

“For dinner, researchers provided participants with a dinner meal (Marie Callender’s Vermont Creamy Mac & Cheese) and a snack (animal crackers) containing 58.7% energy from carbohydrates, 28.9% energy from fat, and 12.7% energy from protein,” the study authors explained.

At each visit, participants first completed assessments of sleepiness and motivation, followed by the COMPASS battery of cognitive tests. They were then given one of two shakes to consume. On one visit (the control condition), the shake primarily consisted of heavy whipping cream, 1% milk, and Nesquik chocolate powder. On the other visit (the experimental condition), the shake consisted primarily of 68 grams of pecans, 1% milk, and Nesquik chocolate powder.

The two shakes were matched for total calories, sugar, fiber, and fat content, but the control shake had a much higher saturated fat content. Half of the participants received the control shake on the first visit and the pecan-enriched shake on the second; the other half received them in reverse order. Both participants and researchers interacting with them were blinded to which shake was administered at each visit.

One hour after consuming the shake, participants repeated the COMPASS cognitive battery. They completed the battery again 2, 3, and 4 hours after the meal. Blood samples were collected at the same time points.

Results showed that participants performed better after consuming the pecan-enriched shake on 8 of the 23 cognitive tests. These tests assessed processing speed, memory, and learning. In contrast, participants performed better after the control shake on 3 tests—two related to memory and learning, and one related to executive function.

“This work indicates that incorporating pecans into the diet of healthy young adults can elicit acute benefits to cognitive performance and may lead to pecans being considered a cognitively protective dietary source,” the study authors concluded.

The study sheds light on the immediate effects of pecan consumption on cognitive function. However, it remains unclear how long these effects last or whether they extend to real-world outcomes beyond lab-based testing. Additionally, the sample was small and limited to relatively young, healthy individuals, so the findings may not generalize to older adults or clinical populations.

The paper, “Cognitive function in response to a pecan-enriched meal: a randomized, double-blind, crossover study in healthy adults,” was authored by Alyssa J. Guadagni, M. Catherine Prater, Chad M. Paton, and Jamie A. Cooper.