- It is not uncommon for people to experience some cognitive decline as they age.
- Past research shows that certain lifestyle choices can impact a person’s cognitive function as they age, such as eating a healthy diet.
- A new study found the DASH diet showed the strongest and most consistent associations to lower cognitive decline risk and better cognitive function, when compared to five other diets.
It is not uncommon for people to experience some cognitive decline as they age. However, the goal is to keep your brain healthy and working correctly for as long as possible.
Past research shows that certain lifestyle choices can impact a person’s cognitive function as they age, such as not smoking, managing stress, getting enough sleep, staying physically active, and eating a healthy diet.
Knowing that consuming a nutritious diet for brain health is great, but which diet is best?
A new study published in the journal
For this study, researchers analyzed health data from more than 159,000 participants with an average age of 44 from the Nurses’ Health Study, Nurses’ Health Study II, and the Health Professionals Follow-Up Study. Scientists focused on data for six dietary patterns:
- Alternate Healthy Eating Index 2010
- DASH diet
- Healthful Plant-Based Diet Index
- Planetary Health Diet Index
- Reversed empirical dietary indices for hyperinsulinemia and inflammatory pattern
“Few studies have systematically compared multiple dietary patterns for cognitive health within the same populations,” Kjetil Bjornevik, MD, PhD, assistant professor in the Departments of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health and senior author of this study, told Medical News Today.
“We chose six patterns representing different dietary approaches so we could assess which showed the most consistent associations using the same methods and participants,” he said.
“Dementia is projected to affect 150 million people by 2050, and we lack treatments that reverse it once established. That makes identifying modifiable risk factors like diet essential for early prevention.”
— Kjetil Bjornevik, MD, PhD
Among the six patterns, Bjornevik said, the DASH diet showed the strongest and most consistent associations with both lower subjective cognitive decline and better objectively measured cognition.
Additionally, researchers discovered that certain food types, such as vegetables, fish, and moderate wine consumption, helped to lower the risk of cognitive decline and led to improved cognitive function.
“These results help identify which dietary components may be driving the associations,” Bjornevik said
“Vegetables and fish were consistently linked to better outcomes, while red and processed meats, fried potatoes, and sugary beverages were linked to worse outcomes. The wine finding should be interpreted cautiously, as moderate drinking correlates with other Health-conscious behaviors,” he explained.
MNT spoke with Dung Trinh, MD, an internist with MemorialCare Medical Group and the chief medical officer of the Healthy Brain Clinic in Irvine, CA, about this study.
Trinh commented that his first reaction to the study’s findings is that it’s encouraging because it adds fairly strong observational evidence — across very large, long-running cohorts — that diet quality is consistently linked with lower risk of subjective cognitive decline, and that the signal is present even when researchers look at long-term patterns over decades.
“It also reinforces a message I already give patients: you don’t need a ‘perfect’ or exotic diet — steady, practical improvements in overall eating patterns appear to matter, especially starting in midlife,” he continued. “At the same time, I’d emphasize this is not proof of causation, but it’s highly actionable and aligns with what we know about cardiovascular and metabolic health and the brain.”
Trinh said a plausible reason as to why the DASH diet may be most helpful in lowering cognitive decline risk is that DASH most directly targets the physiologic systems that are tightly tied to brain health: blood pressure control, vascular function, metabolic health, and inflammation.
“The brain is highly dependent on healthy blood vessels and stable metabolic signaling,” he continued. “DASH emphasizes vegetables, fruits, whole grains, legumes, and limits sodium and red/processed meats — features that tend to improve cardiovascular risk factors and reduce inflammatory burden.”
“In this paper, DASH showed the strongest association with lower subjective cognitive decline risk and also correlated with slightly better objective cognition, which fits the idea that the ‘vascular/metabolic’ pathway may be a major driver of cognitive aging,” added Trinh.
“The DASH diet’s emphasis on vegetables, nuts, and whole grains, while limiting sodium and sugar, has been shown to lower blood pressure, and hypertension is a recognized risk factor for cognitive decline. Beyond blood pressure, the diet is rich in antioxidants and anti-inflammatory nutrients that may reduce oxidative stress and neuroinflammation, and its nutrient profile may support vascular health and insulin sensitivity, both increasingly recognized as relevant to brain health. We did not directly test these mechanisms, so further research is needed.”
— Kjetil Bjornevik, MD, PhD
We asked Monique Richard, MS, RDN, LDN, a registered dietitian nutritionist and owner of Nutrition-In-Sight, for her top tips on how to use what we eat to potentially help lower dementia risk and preserve cognitive Health, whether you plan to follow the DASH diet or not.
“As a dietitian, what excites me most is the possibility of prevention and intervention with the power of nutrition-rich nourishment,” Richard commented. “Cognitive decline is multifactorial, nutrition is one of the few modifiable risk factors we can influence daily. Small, consistent shifts toward more plants, better blood sugar regulation, and vascular support can compound over time.”
For readers who may not be able to follow the DASH diet completely, Richard advised integrating some of its concepts, such as strategically increasing fruit and vegetable intake, into their current diet.
Richard said to aim for 5–8 servings daily, with each serving equal to 1/2 cup cooked or 1 cup raw, with color and family variety, such as beans, leafy greens, and members of the allium family like garlic, onion, and chives.
“Why are variety, quality, and amount so important? Deeply colored plants — berries, leafy greens, cruciferous vegetables — provide flavonoids and carotenoids linked to slower cognitive decline. Leafy greens supply folate and vitamin K, nutrients associated with better cognitive performance. Polyphenols support cerebral blood flow and may enhance synaptic signaling,” Richard explained.
Richard also advised adding one plant to every meal and snack, protecting your blood vessels by assessing the amount of sodium you consume in a day from ultra-processed foods, increasing your intake of potassium-rich foods, and prioritizing fiber-rich foods, such as whole grains, lentils, and fruit with its pith and/or skin.
“The gut-brain axis is an emerging and exciting area in dementia research,” Richard continued. “Your fork is one of your most powerful brain-health tools to help build, or even possibly restore, cognitive resilience, building a foundation bite by bite, meal by meal.”
