“Food as Medicine” has become a major paradigm in preventive health care, and for good reason. While food is not literally medicine, evidence does support nutrition as an important tool in the prevention, management, and sometimes treatment of numerous health conditions. Cognitive health has been one food-as-medicine focus, often centered on the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet, which was designed to merge brain-boosting aspects of the Mediterranean and DASH eating patterns.
However, while early observational studies found benefits of the MIND diet for dementia protection,1,2 2023 randomized clinical trial data provided more nuanced—and initially disappointing—results.3 This evolution in the research highlights both the promise and the complexity of “Food as Medicine.”
From Early Promises to Reality Check
Developed in 2015 by nutritional epidemiologist Martha Clare Morris, ScD, and colleagues at Rush University Medical Center in Chicago, initial cohort studies found that high adherence to the MIND diet—which is rich in leafy greens, berries, nuts, beans, and fish—was associated with not just slowed cognitive decline1 but also up to a 53% lower risk of developing Alzheimer’s disease. Even moderate adherence showed an Alzheimer’s disease risk reduction of about 35%, generating excitement in public health.2 Among the proposed biological mechanisms were that the diet’s richness in polyphenols from berries and lutein/folate from leafy greens reduced oxidative stress and neuroinflammation, while lower intake of saturated and trans fats protected cerebral microvasculature.
To confirm the observational research findings, a Phase 3 randomized controlled trial tested the effects of a three-year intervention of the MIND diet on cognitive decline and brain neurodegenerations. The trial enrolled 604 adults age 65 or older with a family history of dementia, a BMI of at least 25, and a MIND diet score of eight or less (on a scale of 0-14). Participants were randomly assigned to the MIND diet or a control diet, both of which also included a reduction of 250 kcals per day in order to facilitate weight loss. All participants also received counseling from dietitians.3
According to 2023 trials results,3 both the MIND diet group and the control group showed small improvements in global cognitive function—as assessed by an established battery of 12 publicly available cognitive function tests—but there was no statistically significant difference between the groups. Brain MRI markers also showed no significant differences between groups.
Why Results Differed: Methodological Context
A 2025 systematic review found that all of the reviewed observational studies demonstrated positive outcomes from adherence to the MIND diet.4 So why were the clinical trial findings so different? In trying to understand the discrepancy, a few potentially valid points have been made:
• The two groups started with nearly identical MIND diet scores (7.7 in the MIND diet group and 7.8 in the control diet group). While the MIND diet group increased their average score by 3.3 points, the control group increased their score by an average of 0.7 points, which suggests that these participants also made improvements to their diets.
• Both groups lost about 5 kg, suggesting that overall metabolic improvements may have driven cognitive gains in both study arms. It’s been suggested that future clinical trials should include participants from across the weight spectrum and strive for weight stability.
• A three-year trial in healthy older adults may be too short to detect between-group differences compared with decades of observational eating patterns.
Interestingly, a 2026 post-hoc analysis of the MIND trial looked at associations between changes in MIND diet score and improvements in global cognitive function. They found that, regardless of assigned diet group, participants with mean absolute increase of four points on the MIND diet scale showed a significant annual increase in global cognitive composite scores, as well as higher plasma levels of lutein-zeaxanthin and beta-carotene. More modest increases in the MIND diet score were not associated with significant changes in cognitive function.5 This suggests that there may have been significant confounding in the clinical trial.
Another potential confounder in any dietary clinical trial is that careful diet-followers tend to be healthier in other ways, so it can be difficult to conclude that the diet alone was responsible for observed changes.
Reframing “Food as Medicine” in Light of the Evidence
It’s well-known that even well-controlled dietary interventions can produce variable effects among a group of individuals. One possible reason for this—and another potential confounder—is the gut microbiome. Several studies have found associations between alterations in gut microbiome composition and cognitive impairment and overall evidence supports a role of the gut microbiome in mediating the well-established health benefits of fruits and vegetables.
As much as 90% to 95% of phytochemicals are not absorbed in the small intestine. Rather, gut microbes are responsible for their biotransformation, which increases phytochemicals’ bioavailability, absorption, and antioxidative effects. In some respects, this is similar to how the gut microbiota produces beneficial end products, such as short-chain fatty acids (SCFAs) from fermentable fiber.6
A 2026 study reviewed hundreds of laboratory, animal, epidemiological, and clinical studies on polyphenols, natural plant compounds concentrated in berries, tea, cocoa, coffee, and extra virgin olive oil. The review found these compounds may support nerve cell function through antioxidant and anti-inflammatory effects and help counter the biological processes behind Alzheimer’s disease. A key wrinkle noted by the researchers is that, again, most polyphenols are not absorbed directly but are converted by gut bacteria first, and since everyone’s gut bacteria differ, the same food may not work the same way in everyone.7
Of course, the gut-diet connection is a two-way street. A 2026 case-control study of 30 patients with Alzheimer’s disease and 30 cognitively healthy controls found that adoption of the MIND dietary pattern produced clinically relevant changes in both food choices and the gut microbiome. However, the study was not sufficiently powered to detect a hard clinical endpoint.8
These results align with the growing body of evidence suggesting or actually demonstrating the role of diet in shaping the microbiota–brain connection. Mediterranean-like dietary patterns have been shown to promote greater microbial diversity, enrich SCFA-producing organisms, and reduce systemic inflammation. In addition, dietary interventions and microbiota-targeted approaches such as probiotics and prebiotics have shown promise in modulating cognitive trajectories, although results are mixed.8
Conclusion: Moving Beyond “Single-Diet Solutions”
Looking at the broader body of evidence, long-term epidemiological studies, such as the PREDIMED trial for Mediterranean diets, still show strong associations with cardiovascular and long-term cognitive health. Additionally, core components of the MIND diet (leafy greens, nuts, berries, olive oil, fish) play a role in reducing metabolic disease risk. This reminds us that dietary patterns support brain health through broader cardiovascular, metabolic, and systemic mechanisms and pathways rather than acting as a targeted pharmaceutical that works in isolation.
The bottom line is that the unfolding story of MIND diet research suggests that when it comes to cognitive health, “Food as Medicine” is best understood not as a quick fix, but as a lifelong foundational habit that supports brain health indirectly by keeping the cardiovascular and metabolic systems resilient. While dietary interventions can be effective, it may be more through overall health improvement than a singular “brain-only” formula. The key might be to focus on overall diet pattern quality rather than strict scorekeeping and to combine dietary improvements with other key lifestyle “medicines”—exercise, sleep quality, vascular health management, and cognitive engagement.
— Carrie Dennett, MPH, RDN, is editor of Today’s Dietitian.
References
1. Morris MC, Tangney CC, Wang Y, et al. MIND diet slows cognitive decline with aging. Alzheimers Dement. 2015;11(9):1015-1022.
2. Morris MC, Tangney CC, Wang Y, Sacks FM, Bennett DA, Aggarwal NT. MIND diet associated with reduced incidence of Alzheimer’s disease. Alzheimers Dement. 2015;11(9):1007-1014.
3. Barnes LL, Dhana K, Liu X, et al. Trial of the MIND diet for prevention of cognitive decline in older persons. N Engl J Med. 2023;389(7):602-611.
4. Tse JHW, Law QPS, Tsang JTY, Suen LKP, Tyrovolas S, Kwan RYC. The association between the MIND diet and cognitive health in middle-aged and older adults: a systematic review. J Nutr Health Aging. 2025;29(9):100630.
5. Dhana K, Aggarwal NT, Ventrelle J, et al. Adherence to the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet and longitudinal changes in global cognition: a post hoc analysis of the MIND trial. Am J Clin Nutr. 2026;124(3):101433.
6. Armet AM, Deehan EC, O’Sullivan AF, et al. Rethinking healthy eating in light of the gut microbiome. Cell Host Microbe. 2022;30(6):764-785.
7. Mózes N, Varga JT, Szwajgier D, et al. Dietary polyphenols in brain aging: molecular mechanisms and implications for neurodegeneration. Nutrients. 2026;18(9):1470.
8. Di Renzo L, Raffaelli G, Pala B, et al. MIND pattern nutritional intervention modulates mediterranean diet adherence and gut microbiota in Alzheimer’s disease: an observational case-control study. Nutrients. 2026;18(2):193.