Researchers are testing whether walnuts can help people who notice their memory and thinking skills aren’t as sharp as they used to be. About 1 in 9 Americans over 45 experience this early warning sign of brain decline. In this study, 78 adults will eat either walnuts or a chocolate snack for a week, then switch to the other snack after a break. Scientists will measure how well their brains work before and after eating, looking at memory, attention, and thinking speed. Walnuts contain healthy fats and plant compounds that might protect the brain, so researchers want to see if they can make a real difference in how people think and remember.

The Quick Take

  • What they studied: Whether eating walnuts can improve thinking and memory in people who feel their brain isn’t working as well as it used to
  • Who participated: 78 adults aged 45 and older who have noticed some decline in their memory or thinking skills but don’t have diagnosed dementia
  • Key finding: This is a study protocol (the research plan), not yet completed results. The study is designed to measure if one week of eating walnuts improves brain function compared to eating a chocolate snack
  • What it means for you: If walnuts help, it could be a simple, tasty way to support brain health. However, we need to wait for the actual results before knowing if this works. This is still in the testing phase

The Research Details

This is a carefully designed experiment called a ‘crossover trial,’ which means each person tries both options. For 7 weeks total, 78 adults will eat either a walnut snack or a chocolate snack for one week, then take a 4-week break, then switch to the other snack. Before the study starts, everyone eats their assigned snack for one week to get used to it. The researchers will test how well people’s brains work right after eating the snack and again after eating it every day for a week. They’ll measure memory, attention, and thinking speed using special computer tests from the National Institutes of Health. The study is ‘single-blind,’ meaning participants don’t know which snack is the walnut snack and which is the chocolate snack, so their expectations won’t affect the results.

This research design is strong because each person serves as their own comparison—we can see how the same person’s brain works with walnuts versus without them. This removes differences between people that might confuse the results. Testing brain function both right after eating and after a week of eating helps show whether walnuts have quick effects or need time to work. The researchers also collected information about what people ate, how much they exercised, and samples of their gut bacteria to understand how walnuts might help the brain.

This study has several strengths: it uses a recognized test for brain function (NIH Toolbox), includes a control group for comparison, and keeps participants blinded to reduce bias. The study was completed as planned with recruitment finishing in May 2025. However, this is the study protocol (the plan), not the actual results yet, so we don’t know if the findings will be significant. The sample size of 78 is moderate—large enough to find real effects but not huge.

What the Results Show

This document describes the study plan, not the actual results. The researchers have not yet published what they found about whether walnuts improved brain function. The study measured cognitive function (thinking and memory skills) using standardized tests before eating the snack, right after eating it, and after one week of daily snack consumption. They compared how people’s brains worked after eating walnuts versus after eating the chocolate snack. The study also looked at whether eating walnuts for a week changed brain function more than eating the chocolate snack. Results will show whether the differences between the two snacks were meaningful and statistically significant (unlikely to be due to chance).

The researchers also measured how much healthy fats from walnuts got into people’s red blood cells after one week of eating them. They collected stool samples to see if walnuts changed the types of bacteria in people’s guts and whether they produced more of a beneficial substance called butyrate. They tracked weight and waist circumference to make sure people didn’t gain weight from the extra calories in walnuts. They also recorded what people ate and how much they exercised to understand other factors that might affect brain function.

Previous research has suggested that walnuts might help brain health because they contain omega-3 fats and polyphenols (plant compounds with antioxidant properties). Some studies have shown benefits for memory and thinking in older adults. However, most previous research looked at long-term walnut consumption (weeks or months), not whether a single meal or one week of walnuts could quickly improve brain function. This study fills that gap by testing whether walnuts have immediate effects on how the brain works after eating.

This is a study protocol, so we don’t yet know the actual results or real-world limitations. However, the design has some built-in limitations: the study only lasts 7 weeks total, so it can’t show whether long-term walnut eating helps more than short-term. The chocolate snack may not be the best comparison because it has different nutrients than walnuts in multiple ways. The study includes only people with subjective cognitive impairment, so results may not apply to people with normal thinking or diagnosed dementia. The study is relatively small (78 people), which means results might not apply to everyone.

The Bottom Line

Wait for the actual study results before making changes based on this research. Once results are published, eating a small handful of walnuts (about 1 ounce or 23 walnuts) daily may support brain health, especially if you’ve noticed your memory or thinking isn’t as sharp. Walnuts are already recommended as part of healthy diets for heart and brain health, so adding them is unlikely to cause harm. However, they are high in calories, so eat them instead of other snacks, not in addition to your normal diet. Confidence level: Low to moderate—we’re waiting for the actual results.

This research is most relevant to adults over 45 who have noticed their memory or thinking skills declining but don’t have diagnosed dementia. It may also interest people with a family history of memory problems or dementia who want to prevent decline. People with nut allergies should not participate. If you have a medical condition affecting your brain or take medications that interact with foods, talk to your doctor before making dietary changes. This research doesn’t yet apply to people with normal brain function or diagnosed dementia.

If walnuts help, the study suggests benefits might appear quickly—possibly within hours of eating them or within one week of daily consumption. However, brain health improvements often take longer, and this study only tested short-term effects. For meaningful, lasting improvements in memory and thinking, expect to eat walnuts regularly for weeks to months. Don’t expect dramatic changes; any benefits would likely be subtle improvements in focus, memory, or thinking speed.

Want to Apply This Research?

  • Track daily walnut consumption (number of walnuts or ounces eaten) and rate your mental clarity, focus, and memory each evening on a scale of 1-10. Note the time of day you eat walnuts and when you notice any changes in how your brain feels
  • Set a daily reminder to eat a small handful of walnuts (about 1 ounce) at the same time each day, such as with breakfast or as an afternoon snack. Log this in your app and note any changes in your ability to concentrate, remember things, or think clearly
  • Track walnuts eaten daily for at least 4 weeks to see if consistent consumption correlates with improvements in your subjective sense of mental sharpness. Use the app to record weekly self-assessments of memory and focus, looking for trends over time. If you notice improvements, continue the habit; if not, you’ve still added a nutritious food to your diet

This article describes a research study protocol, not completed results. The study has not yet published its findings about whether walnuts improve brain function. This information is for educational purposes only and should not replace professional medical advice. If you have concerns about memory loss or cognitive decline, consult your doctor for proper evaluation and personalized recommendations. People with nut allergies should avoid walnuts. Always talk to your healthcare provider before making significant dietary changes, especially if you take medications or have medical conditions. This research applies only to people with subjective cognitive impairment and may not apply to you.