Healthy eating habits can help prevent cognitive decline later in life

• A healthy diet has been linked to a reduced risk of many health conditions, including heart disease and certain cancers.
• New research has added to evidence that eating a varied, plant-rich diet may decrease the risk of cognitive decline and dementia later in life.
• The findings show that an unhealthy diet is strongly associated with lower cognitive abilities, but a high quality diet during youth and middle age helps maintain brain health as you age.
• Adopting healthy eating habits at any age will improve your chances of staying mentally sharp as you grow older.

There’s plenty of evidence that a diet rich in plants and low in salt, saturated fats, and processed foods benefits overall health. Healthful diets can reduce the risk of cardiovascular disease , diabetes , and cancer .

Several studies have shown that eating a healthy diet in older age can help reduce the risk of cognitive decline and dementia .

Now, research presented at NUTRITION 2024 , the annual meeting of the American Society for Nutrition, has provided further evidence that healthy eating throughout life is key to maintaining cognitive function as we age.

The study suggests the earlier that people adopt healthy eating patterns, the more likely they are to stay mentally sharp into old age.

The findings have not yet been published in a peer-reviewed scientific journal.

Kelsey Costa , a registered dietitian and science communications officer at Examine, told Medical News Today :

“This study adds to the growing body of evidence that suggests a strong link between diet and cognitive health, highlighting the importance of dietary choices in maintaining brain function as we age. The main novelty of the study is that it tracked cognition along with self-reported diet across the lifespan, which is one of the major contributions of the research.”

Studying the effects of diet on cognition

The study collected data from 3,059 people over seven decades. All participants were born in March 1946 and enrolled as children into the Medical Research Council’s National Survey of Health and Development in the United Kingdom.

Over the course of more than 75 years, the participants in this survey completed questionnaires and tests on diet, cognition, general health, and other factors.

For this study, the researchers assessed participants’ dietary intakes at five time points between the ages of 4 and 63, using recall and food diaries. They also measured their cognitive ability at seven time points between ages 8 and 69.

They then used group-based trajectory modeling to investigate the relationship between diet and cognition.

Scott Kaiser, MD , board certified geriatrician and director of Geriatric Cognitive Health for the Pacific Neuroscience Institute in Santa Monica, CA, told MNT :

“While this study, and other related cornerstone studies in this field, may not be designed to specifically establish causation there are many clear causal pathways and plausible biological mechanisms that support the likelihood that various diets and nutritional factors may either be protective of our brain health or accelerate cognitive decline and otherwise impact our mental well-being.”

Healthy eating at any age benefits brain health

The researchers used the 2020 Healthy Eating Index (HEI) from the U.S. Department of Agriculture Health and Nutrition Service to assess the quality of the participants’ diets.

In this index, higher intakes of foods such as fruits and vegetables, whole grains, protein, dairy, and seafood increase scores, while higher intakes of refined grains, sugar, sodium , and saturated fats reduce scores.

The researchers found a strong association between diet quality over time and cognitive trajectory.

Participants who retained high cognitive abilities into older age tended to eat more of the index’s high-scoring foods, such as vegetables, fruits, legumes, and whole grains, and less added sugars , refined grains, and sodium —the foods that decreased HEI scores.

According to the study abstract, 47% of participants with the lowest-quality diets were in the lowest cognitive trajectory, and only 7% were in the highest cognitive trajectory. Conversely, 48% of those with the highest-quality diets were in the highest cognitive trajectory (8% in the lowest cognitive trajectory).

Although all participants tended to adopt a healthier diet in adulthood, differences in diet quality in childhood influenced later life dietary patterns, as lead researcher Kelly Cara, PhD , Friedman School of Nutrition Science and Policy at Tufts University, noted:

“This suggests that early life dietary intakes may influence our dietary decisions later in life, and the cumulative effects of diet over time are linked with the progression of our global cognitive abilities,” she said in a press release .

Costa agreed, but emphasized that improving diet later in life can still have a beneficial effect.

“The findings reported […] suggest making changes to have a healthier diet up to midlife correlate well with later-life cognitive outcomes,” Costa said. “This adds a ray of hope that the effects of an early poor diet can be at least somewhat reversed.”

How a healthy diet affects cognitive function

Diets shown to have health benefits include a high intake of fruits, vegetables, and whole grains, combined with low consumption of sugars, saturated fats , and processed foods . These include the Mediterranean , DASH , and MIND diets.

“A diet rich in antioxidants and anti-inflammatory components, such as fruits, nuts, vegetables, dietary fiber , and omega-3s, may help reduce age-related cognitive decline and lower the risk of neurodegenerative diseases,” Costa said.

“These nutrients protect brain cells from damage related to oxidative stress , support brain structure and function, and maintain a healthy vascular system, which helps promote healthy blood flow to the brain,” she added.

Dr. Kaiser explained the MIND diet to MNT :

“A combination of Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets, the “Mediterranean-DASH Intervention for Neurodegenerative Delay” (MIND) diet has been demonstrated to slow brain aging by something on the order of 7.5 years and significantly reduce one’s risk of developing Alzheimer’s disease.”

All these diets provide a high intake of polyphenols , plant compounds that can help protect against development of chronic health conditions, such as:

• certain forms of cancer
• cardiovascular disease
• diabetes
• osteoporosis
• neurodegenerative diseases

Polyphenols are antioxidants that combat cell damage and have anti-inflammatory and neuroprotective effects.

Costa advised the following dietary recommendations:

“Brain-healthy foods generally include green leafy vegetables, berries, whole grains, nuts, seeds, beans, seafood, poultry, and olive oil. In contrast, red meat, cheese, butter, refined grains, sweets, pastries, and fried or fast food are considered less optimal for brain health. However, healthy eating is not just about specific foods; it’s also about the overall balance of nutrients and calories consumed.

Ultimately, adopting a healthy diet rich in brain-boosting foods can help maintain mental alertness and overall vascular health, encouraging a sharper mind well into older age.”