Maintaining the Brain as We Age

The human brain generally represents around 2 percent of the body by weight and consists of billions of neurons. These neurons are so demanding of resources that the brain ultimately requires 20 percent of our metabolic energy—a need 10 times higher per gram than muscle.

With great power, as they say, also comes great responsibility.

Even in otherwise healthy people, the volume of the human brain declines, in multiple areas, with age—representing a loss of neurons and disruption of their connectivity.

Overall cognitive health and capacity is highly correlated with brain volume, and brain volume is also highly correlated with one’s metabolic health. As an example, fatty liver disease is an increasingly common metabolic disorder strongly related to dietary factors. People who have fatty liver disease experience accelerated declines in brain volume and higher risks of cognitive health concerns like dementia.

Nutrition and healthy brain -aging

The relationship between liver and brain health serves as a tangible example of the strong connection between healthy brain aging and good nutrition. A 2024 brain-imaging study in older adults compared intake measures of key nutrients with signs of brain health, identifying the foods and nutrients most strongly associated with slower brain aging.

Omega-3 fatty acids

Individuals who demonstrated signs of delayed brain aging tended to have higher bodily concentrations of the anti-inflammatory omega-3 fatty acids eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA). Inflammation is considered a hallmark of brain aging as it disrupts the blood-brain barrier, making the brain more susceptible to structural damage over time.

EPA and DHA are found in fatty fish like salmon, sardines, and trout, while ALA is found in flaxseed, hempseed, chia seed, soy-based foods, and walnuts.

Carotenoids

Carotenoids are strong antioxidants known to concentrate in areas of the brain and eyes relative to the amount they are consumed. Oxidative stress, which carotenoids help to combat, is considered another hallmark of brain aging. It’s unsurprising that a high carotenoid intake was associated with better brain health.

Carotenoid sources include spinach, kale, bell peppers, tomato, watermelon, broccoli, carrots, grapefruit, and cantaloupe.

Vitamin E and choline

Another strong antioxidant associated with healthier brain aging, vitamin E has inspired multiple studies demonstrating that having higher bodily levels is associated with better cognitive health. Vitamin E is found primarily in nuts, seeds, leafy greens, and fish.

Choline is a precursor to creating a compound known as phosphatidylcholine, which populates brain cell membranes and regulates the release of various neurotransmitters required for optimal brain function. Choline is found in foods including eggs, edamame, cauliflower, beef, chicken, peas, pork, broccoli, and milk.

Additional nutrients

With age, certain nutrients may not be absorbed as readily (take iron, for example), while others—like potassium, magnesium, and calcium—may be under-consumed, the consequences of which accrue as we age. One such consequence may be high blood pressure, a meaningful risk factor for cognitive decline. Potassium, calcium, and magnesium are all nutrients known to help regulate blood pressure.

  

The gut-brain connection

No conversation on healthy brain aging is complete without reference to the gut-brain connection, which is heavily mediated by the trillions of bacteria and other species that make up our gut microbiome―a microbiome that also changes as we age.

Older adults with cognitive issues are much more likely to have a gut microbiome characterized by imbalances in good and bad bacteria, with an overrepresentation of pro-inflammatory species.

A healthy gut microbiome produces beneficial compounds known as short-chain fatty acids (SCFAs), which have an anti-inflammatory influence and facilitate healthy gut-brain communication via multiple pathways.

These influences include enhanced nutrient absorption and keeping the intestinal lining strong, thus preventing toxins from entering the blood stream and crossing the blood-brain barrier via the gastrointestinal tract. This is where polyphenols come in.

Polyphenols―the gut-brain connectors

Polyphenols are a family of plant-based compounds known to encourage gut bacteria to produce beneficial SCFAs.

In 2018, Neurology published a study—involving 1,329 older adults followed over 12 years—that found those in the highest consumption category of polyphenols had a 50 percent lower risk of dementia than those in the lowest consumption category.

Easy ways to boost your dietary exposure to polyphenols include cocoa powder, ground flaxseed, artichoke, blueberries, and more frequent use of culinary herbs/spices.

Beyond nutrition―expert insight

Barbie Boules, registered dietitian, says, “If I had to narrow it down to two top tips for brain health that have a same-day impact on brainpower and improve your long-term odds, it’s go to bed and move your body. More specifically, do everything in your power to protect eight good-quality hours of sleep, and prioritize 30 minutes of movement daily. And remember, it doesn’t need to be fancy—walking counts.”

Boules’s recommendations are strongly supported by research: poor sleep habits and sedentary behavior are both associated with accelerated brain aging and poorer cognitive health.