Eating Blueberries and Chicken May Slow the Shrinking of Your Brain

Every year, without your noticing, your brain gets a little smaller. Grey matter contracts, the fluid-filled chambers inside the skull expand slightly outward, and the tissue that does most of your remembering and deciding quietly retreats. This is not pathology; it is simply ageing, written in cubic centimetres. What a new study from the Framingham Heart Study suggests, though, is that what you eat might influence the rate at which that clock runs.

For more than a decade, researchers tracked nearly 1,650 middle-aged and older Americans, measuring their brain volumes with MRI every few years while also recording, in considerable detail, what they ate. The question was whether adherence to the MIND diet, a dietary pattern designed specifically to protect the ageing brain, was associated with slower structural changes over time. The answer, it turns out, is yes, though with some rather unexpected wrinkles.

The MIND diet (which stands for Mediterranean-DASH Intervention for Neurodegenerative Delay, a name so unwieldy it perhaps explains why researchers universally prefer the acronym) combines elements of two well-established eating patterns: the Mediterranean diet and the DASH diet, which was developed to lower blood pressure. Where MIND differs is its particular focus on foods thought to benefit the brain, above all dark leafy vegetables, berries, nuts, whole grains, fish, beans, poultry, and olive oil, while encouraging limits on butter, cheese, red meat, pastries, and fried fast food. Previous work had linked the diet to slower cognitive decline and lower risk of Alzheimer’s disease, but whether it actually changed the physical structure of the brain over years was a harder question to answer. Cross-sectional studies, which take a single snapshot in time, can show associations but cannot tell you about the direction of change.

The Framingham data offered something rarer. Participants had brain scans repeated two to three times over a median of twelve years, giving researchers a genuine view of how brain structure evolved. Dietary intake had been recorded at multiple points in the 1990s, before the imaging began, which matters because it reduces the risk that early disease was already influencing what people chose to eat.

The headline finding is striking in its precision. Each three-point improvement in a participant’s MIND diet score, on a scale running from zero to fifteen, was associated with grey matter shrinking roughly 0.28 cubic centimetres per year more slowly than in lower-scoring participants. That translates, the researchers calculate, to about 20 percent less age-related grey matter loss during the study period, or the equivalent of slowing the ageing clock by two and a half years. A similar pattern appeared for ventricular expansion, the outward creep of the brain’s fluid spaces that accompanies tissue loss: higher MIND scores were linked to about 8 percent less enlargement over the follow-up period, roughly one year’s worth of delayed ageing.

The foods driving most of the benefit were berries and poultry. Both were associated with slower ventricular expansion; poultry also appeared to protect grey matter volume independently. The researchers suggest that antioxidants in berries may reduce oxidative stress and mitigate neuronal damage, while poultry provides high-quality protein that perhaps supports neuronal maintenance. Conversely, fried fast foods and sweets were associated with faster hippocampal atrophy, the hippocampus being a structure deeply involved in memory and particularly vulnerable to the early stages of neurodegeneration.

Two findings broke from expectation in ways the authors flag as genuinely puzzling. Higher whole grain intake, supposed to be among the diet’s most protective elements, was associated with faster grey matter and hippocampal decline in this dataset, and with increased ventricular expansion. Cheese, explicitly restricted by the MIND diet, was associated with slower grey matter and hippocampal decline and less ventricular enlargement. Neither result has a clean explanation. The researchers do not dismiss the findings, but they are appropriately cautious: these are secondary analyses within a larger pattern, and the counterintuitive signals may reflect unmeasured confounders, differences in the types of whole grains or cheeses consumed, or simply statistical noise that will not survive replication.

There are real limits to what this kind of study can conclude. No randomised trial can ethically assign participants to decades of eating particular foods. Observational data, however carefully analysed, leaves residual confounding: people who eat more berries and less fast food also tend to exercise more, smoke less, and have lower rates of diabetes and cardiovascular disease, all of which independently affect the brain. The Framingham cohort is predominantly White and relatively well-educated, which limits how far these findings travel to other populations.

The subgroup analyses add nuance worth noting. The associations were meaningfully stronger in participants over sixty than in younger adults, suggesting that the diet’s structural benefits may be most pronounced when brain ageing is already accelerating. They were also stronger in more physically active participants and in those who were not overweight, which fits a broader picture in which lifestyle factors interact rather than operate in isolation.

Grey matter is not an abstraction. It houses the neuronal cell bodies, dendrites, and synapses that underpin memory, learning, and the capacity to make decisions. The ventricles, in contrast, are spaces; when they enlarge, it is because the surrounding tissue has contracted. Slowing either process does not prevent ageing, but in a landscape where no pharmacological intervention has yet demonstrated convincing efficacy against neurodegeneration at population scale, the possibility that diet might offer a partial brake is not a small thing. Berries and chicken are considerably more accessible than any drug currently in clinical trials for Alzheimer’s disease, and considerably cheaper.

What remains unknown is whether starting the MIND diet in midlife is equivalent to starting it earlier, or whether a decade of adherence is substantially different from two. Randomised controlled trials of shorter duration have given mixed results on cognitive outcomes, which may simply mean that structural changes to the brain require years of intervention to become detectable. The Framingham data suggests the timescale for dietary effects on brain structure is long, probably measured in decades, which makes the results harder to test but rather more relevant to the choices people make at every meal.

DOI / Source: https://doi.org/10.1136/jnnp-2025-336957