A new long-term study of nearly 90,000 people has given fresh weight to the idea that what we eat might help protect our minds as we age. Researchers from the Harvard T.H. Chan School of Public Health have found that older adults who closely followed the MIND diet—a hybrid of the Mediterranean and DASH diets—had up to a 29% lower risk of developing dementia compared to those who followed it the least. The findings were published in May 2025 and have been widely hailed as a major step forward in our understanding of nutrition and cognitive health.
The MIND diet, short for Mediterranean-DASH Intervention for Neurodegenerative Delay, focuses on ten food groups that appear to benefit the brain—like green leafy vegetables, berries, nuts, whole grains, and olive oil—and encourages people to limit red meat, butter, cheese, pastries and fried food. It’s not exactly radical, but the size and duration of this study make the case more compelling than ever.
A massive data set and a long view
The research followed 88,958 adults aged 65 and over for more than two decades. Participants were part of the Nurses’ Health Study and Health Professionals Follow-up Study, two large-scale longitudinal studies in the US that have tracked health outcomes in adults since the 1980s. Every four years, participants completed detailed food frequency questionnaires, allowing researchers to score their diets and observe any emerging patterns.
Those whose eating habits most closely followed the MIND diet saw their risk of developing dementia drop by 29% compared to the group with the lowest scores. Even those with moderate adherence saw noticeable benefit. As senior author Dr. Claire McEvoy of Queen’s University Belfast explained, these findings reinforce earlier smaller studies and offer strong evidence for dietary prevention at scale.
Why this matters in the UK right now
In the UK, dementia remains one of the biggest public health challenges. It’s the leading cause of death, affecting around 900,000 people—and that figure is expected to surpass a million by 2030. The NHS spends billions annually on dementia-related care, much of it focused on managing symptoms after they appear.
While genetics and age are key factors, modifiable lifestyle choices—including diet—are gaining serious attention. The UK government’s Office for Health Improvement and Disparities recently included diet quality as a core component of its dementia prevention strategy, citing the growing body of global evidence, including this new Harvard-led study.
What makes the MIND diet different?
Unlike more prescriptive or fad-based regimes, the MIND diet is built around accessibility and flexibility. It doesn’t require cutting out entire food groups or following strict daily macros. Instead, it encourages gradual, achievable changes—like including greens most days, snacking on nuts, or swapping in olive oil for other fats.
Berries, especially blueberries and strawberries, are given special attention. They’re high in flavonoids, which research has linked to slower rates of cognitive decline. Meanwhile, regular servings of leafy greens—think spinach, kale, and rocket—are associated with improved memory and slower brain ageing.
The diet also draws heavily on the Mediterranean tradition of plant-forward meals with moderate fish, whole grains, and minimal processed foods. But unlike standard Mediterranean plans, it specifically limits cheese, butter, and fried foods—all of which have been linked to increased inflammation and vascular damage.
Can changing your diet really make a difference?
Critics often point out that diet alone won’t stop dementia—and that’s true. There’s no miracle cure. But mounting evidence suggests that healthy dietary patterns, combined with regular exercise, sleep, and social engagement, can delay or reduce cognitive decline in many people. As one of the study’s lead authors, Dr. Walter Willett, noted, “The impact of the MIND diet is likely to be cumulative. It’s not about being perfect—it’s about making better choices more often.”
Even in those with a genetic risk of Alzheimer’s, lifestyle factors appear to slow the onset. A 2023 review in The Lancet Neurology suggested that up to 40% of dementia cases could be prevented or delayed through lifestyle changes. The MIND diet, it seems, is one of the most evidence-backed places to start.
The real-life impact of small changes
You don’t need to overhaul your life overnight to take advantage of these findings. Replacing one meat-based meal a week with a fish or legume option, adding a handful of blueberries to your breakfast, or using olive oil instead of butter on toast are all small steps that can add up. The study emphasised consistency over perfection—and the long follow-up period supports the idea that sticking with a mostly brain-friendly diet over time really does pay off.
In the UK, nutrition experts are calling for the NHS and public health bodies to promote the MIND diet more widely. The British Dietetic Association has already expressed support for incorporating it into healthy ageing campaigns, and community health programmes in Manchester and Bristol are reportedly trialling it in new pilot schemes for over-60s.
What happens next?
Researchers behind the study say future work will focus on identifying which parts of the MIND diet are most protective, and whether earlier adoption—say, in midlife—has an even greater impact. There’s also interest in adapting the model for different cultural diets, making it more inclusive and practical across regions.
In the meantime, this research is a solid nudge for people looking to improve brain health as they age. It adds to growing consensus around lifestyle medicine and the idea that prevention, not just treatment, deserves more of the spotlight.
With cases of dementia expected to rise sharply in the next decade, the message is clear: how we eat now could shape not just our physical health, but how clearly we think, remember, and live in the years to come.