There is substantial evidence supporting the benefits of a diet rich in plants and low in salt, saturated fats, and processed foods for overall health. 

Such diets can significantly reduce the risk of cardiovascular disease, diabetes, and cancer. Studies have also shown that eating healthily in older age can help reduce the risk of cognitive decline and dementia.

Recent research presented at NUTRITION 2024, the annual meeting of the American Society for Nutrition, further emphasizes the importance of healthy eating throughout life in maintaining cognitive function as we age. 

The study suggests that adopting healthy eating patterns earlier in life increases the likelihood of staying mentally sharp into old age. While the findings have not yet been published in a peer-reviewed scientific journal, they add to a growing body of evidence linking diet and cognitive health.

Kelsey Costa, a registered dietitian and science communications officer at Examine, stated, "This study highlights the importance of dietary choices in maintaining brain function as we age. Tracking cognition along with self-reported diet across the lifespan is a major contribution of this research."

The study collected data from 3,059 individuals over seven decades. Participants, all born in March 1946 and enrolled as children into the Medical Research Council’s National Survey of Health and Development in the UK, completed questionnaires and tests on diet, cognition, general health, and other factors over 75 years. Researchers assessed participants’ dietary intakes at five time points between ages 4 and 63 and measured their cognitive ability at seven time points between ages 8 and 69. They used group-based trajectory modeling to investigate the relationship between diet and cognition.

Scott Kaiser, MD, Director of Geriatric Cognitive Health for the Pacific Neuroscience Institute, noted, "While this study and others may not be designed to establish causation, there are many clear pathways and plausible mechanisms that suggest various diets and nutritional factors may protect brain health or accelerate cognitive decline."

The researchers used the 2020 Healthy Eating Index (HEI) from the U.S. Department of Agriculture to assess diet quality. Higher intakes of fruits, vegetables, whole grains, protein, dairy, and seafood increased HEI scores, while higher intakes of refined grains, sugar, sodium, and saturated fats decreased them. A strong association was found between diet quality over time and cognitive trajectory. Participants with higher cognitive abilities in older age consumed more high-scoring foods and fewer low-scoring ones.

According to the study, 47% of participants with the lowest-quality diets were in the lowest cognitive trajectory, while only 7% were in the highest cognitive trajectory. Conversely, 48% of those with the highest-quality diets were in the highest cognitive trajectory. Lead researcher Kelly Cara, PhD, from the Friedman School of Nutrition Science and Policy at Tufts University, noted, "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."

Costa emphasized that improving diet later in life can still be beneficial. "The findings suggest that making dietary changes up to midlife correlates well with later-life cognitive outcomes, offering hope that the effects of an early poor diet can be at least somewhat reversed."

Diets shown to have health benefits, such as the Mediterranean, DASH, and MIND diets, include high intakes of fruits, vegetables, and whole grains, and low consumption of sugars, saturated fats, and processed foods. Costa explained that these nutrients protect brain cells from damage related to oxidative stress, support brain structure and function, and maintain a healthy vascular system, promoting healthy blood flow to the brain. The MIND diet, a combination of the Mediterranean and DASH diets, has been demonstrated to slow brain aging and significantly reduce the risk of Alzheimer’s disease.

These diets provide a high intake of polyphenols, plant compounds that help protect against chronic health conditions such as cancer, cardiovascular disease, diabetes, osteoporosis, and neurodegenerative diseases. Polyphenols are antioxidants with anti-inflammatory and neuroprotective effects.

Costa advised including brain-healthy foods such as green leafy vegetables, berries, whole grains, nuts, seeds, beans, seafood, poultry, and olive oil in the diet, while limiting red meat, cheese, butter, refined grains, sweets, pastries, and fried or fast food. She emphasized that healthy eating is not just about specific foods but 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, promoting a sharper mind well into older age.