The Best and Worst Foods for Gut-Brain Health

Source: Austin Perlmutter/DALL-E

In recent years, the gut-brain connection has emerged as a top topic when it comes to brain health. Breakthroughs in research have revealed that the gut contains an extensive network of neurons and communicates directly with the brain through the vagus nerve, immune pathways, the endocrine system, and microbial metabolites. This bidirectional communication plays a critical role in mood regulation, cognition, and overall health.

Understanding how to nourish this connection, then, has profound implications for brain health. In this article, we’re exploring this powerful science and the foods best known to influence the connection

The Gut-Brain Connection: A Two-Way Communication Superhighway

You’ve probably heard talk about the importance of the gut in overall health. This stems from the fact that your gut is tasked with digestion, absorption, immune regulation, metabolism, and so much more.

Yet a rapidly expanding subset of gut-focused research has demonstrated that the state of the gut can significantly influence the brain, and vice versa. The five most important channels linking your gut with your brain are the following:

1. The Enteric Nervous System (ENS): Sometimes described as a "second brain," the ENS is embedded in the gut wall and contains over 100 million neurons. It independently regulates digestion and sends signals to the brain.
2. The Vagus Nerve: Your vagus nerve (cranial nerve 10) is the main physical connection between the gut and the brain, transmitting data from the gut to the brain and motor commands from the brain to the gut.
3. The Microbiome: The trillions of bacteria, fungi, viruses, and other microbes in your gut produce neuroactive compounds such as serotonin, dopamine, and gamma-aminobutyric acid (GABA), along with molecules called short-chain fatty acids (SCFAs). These chemicals all appear to influence mood, behavior, and cognitive function, although the pathways are different from the effects of these molecules when they’re produced in the brain.
4. The Immune System: A large percentage of your immune system is located in your gut and is changed based on your diet and microbiome makeup. The gut immune system may directly or indirectly influence brain function by affecting pathways like inflammation.
5. Endocrine Signaling: The gut produces hormones like ghrelin (hunger hormone), leptin (satiety hormone), and GLP-1, which influence not just appetite but also brain function.

Top Foods to Eat for a Healthy Gut-Brain Connection

1. Polyphenol-rich foods: Polyphenols act as prebiotics, meaning they provide nourishment for beneficial gut bacteria. They also appear to act on immune, metabolic, and other pathways to help regulate overall and brain health. Great sources include tea, coffee, spices, and colorful fruits and vegetables.
2. Fiber-rich foods: Dietary fiber acts as a prebiotic, feeding beneficial gut bacteria. Insufficient fiber is linked to higher rates of immune and metabolic dysfunction that can damage brain health. Insoluble fiber helps with regular bowel movements, while soluble fiber helps feed healthy microbes. Dietary sources of fiber include whole grains, oats, legumes, sunchokes, leafy greens, nuts, seeds, and fruits.
3. Fermented foods: Fermented foods are rich in probiotics, which introduce beneficial bacteria into your gut. These bacteria may help maintain balance in your microbiome and improve digestion. While largely preclinical, data supports the use of fermented food to positively impact pathways linked to gut-brain health. Examples include yogurt (with live cultures), kefir, sauerkraut, kimchi, miso, and kombucha (but look out for high sugar content in some kombucha!)
4. Fatty fish: Fatty fish like salmon and mackerel are high in omega-3 fatty acids like EPA and DHA, which are known regulators of immune function and key to brain health. In the gut, omega-3s may support a more balanced gut microbiome. Examples include salmon, mackerel, sardines, and anchovies. Algae-based sources are also commercially available in supplemental form.

Foods to Avoid for a Healthy Gut-Brain Connection

1. Added sugar: Added sugar is believed to contribute to systemic immune imbalance, including within the gut. This is one of the mechanisms connecting dietary added sugar with higher rates of cognitive issues, mood disorders, and more. Look out for any foods with added sugars, but especially sugary beverages. We are still learning about the effects of artificial and sugar alternatives on the gut-brain link, but some data suggest that stevia, monkfruit, and allulose may be preferable to other alternatives.
2. Highly processed foods: Generally speaking, the more a food has been modified from its original state, with additives, emulsifiers, sugars, salts, and fats, the higher the chances that it’s not great for gut and brain health. In primarily animal data, processed food consumption is linked to inflammation, leaky gut, and microbiome changes. In observational data, these foods are linked to higher rates of gut diseases and disorders. In general, avoiding highly processed food is a good move for everyone.
3. Excess alcohol: While some data indicate that low to moderate amounts of alcohol consumption are linked to better brain health outcomes, the research is clear that excess alcohol consumption damages brain health. Some recent science suggests that alcohol may exert these negative effects (in excess) due to changes in the gut. Generally speaking, research points to two or less alcoholic beverages a day for men and one or less for women as a reasonable threshold.