If there is anything we are all bound to experience in life, it is mood changes; some mild, others severe. Mood changes can be triggered by a myriad of factors, such as the loss of a loved one, excessive stress, lack of sleep, change of hormones with age, or the side effects of medication. The limbic system, a part of the human brain, has been shown to play a key role in these types of behavioural and emotional responses. However, beyond these factors, there are other elements that could have a longer and continued impact on one’s mood if left unaddressed. They include the composition of the bugs living in one’s gut, popularly known as the gut microbiota, and the nature and quality of the food we eat.

Biologically, the brain has a direct link to the gut. This is why the feeling of anxiety before giving a presentation or attending an interview, could cause someone to want to urinate more often. The gut also sends signals to the brain; hence it is common for people with certain gastrointestinal disorders to feel pain more acutely due to their brain’s responsiveness to pain signals from the gastrointestinal tract. This scientific consensus has been well-established in studies. From a clinical perspective, it is essential to create tools that provide practitioners with deeper insight into mood disorders and brain health, from their gut. These tools should be both analytical and sensitive, allowing practitioners to have incremental insight into biomarkers that may modulate their patients’ moods.

A test with strong analytical validity accurately detects the biomarkers or agents associated with a particular condition, such as mood disorders. On the other hand, a sensitive test accurately detects changes in the gut environment due to changes in interventions such as diets, drugs, or lifestyle. Clinically, these tests may be used to detect a pre-symptomatic state or an established disease symptom as part of a preliminary prescriptive screening to contribute directly to a person’s health. Interestingly, gut health has already become a core component of the protocol for practitioners such as gut-brain dietitians, functional and integrative medicine psychiatrists, and naturopaths, who adopt a holistic approach to brain health.

It is important to establish that the relationship between the gut microbiota and mood disorder, like many other gut-related conditions, is associative and not causal. A specific bacterium does not particularly cause or cure mood disorders or any mental health conditions directly. Rather, the relative balance or imbalance of certain gut bacteria modulates chemical, endocrine, and neuronal signaling pathways that affect mood disorders. For example, perturbations in gut bacterial diversity and richness have been reported to influence the roles of dopamine, serotonin and gamma-aminobutyric acid (GABA), all of which are neurotransmitters that contribute to the way we feel. The gut microbiome is a complex ecosystem of microbes that crosstalk using biochemical pathways. Therefore, it is essential to look at the gut-wide balance of different bacterial groups, not as isolated. Increased gut-intestinal permeability, elevated inflammation, dysregulated tryptophan metabolism, neurotransmitter regulation, excessive lipopolysaccharide (LPS) levels, and impaired short-chain fatty acid production are known biological changes in the gut, associated with depressive symptoms through the gut-brain connection. These events are influenced by bacterial dysbiosis in the gut and have far-reaching effects on mood. Thus, creating a gut-bacterial balance can improve mood.

If correcting gut dysbiosis plays a role in improving mood, then it is important to establish how this can be done. Nothing affects the gut more than food. In fact, there is strong epidemiological evidence that a poor diet is associated with mood disorders such as depression. Conversely, a healthy diet has also been associated with a reduced risk or alleviation of depression. To date, the two clinical trial studies conducted to back these numerous observational studies have been successful, implying that diet is a modifiable risk factor for mood disorders. But how does food affect mood? Food affects mood in two ways: food nutrients on a biochemical level impact brain chemistry, and food heavily impacts gut health, which modulates mood through endocrine, immune, and neuronal signaling pathways. Therefore, personalized food and prebiotic interventions, based on the nature of an individual’s gut bacterial shift, can be used to achieve improved mood.

It is important to state here that there is quite a non-homogeneous recommendation pattern for microbiome result profiles among various gut health companies claiming to use AI to generate personalized food interventions for gut-related conditions. Frequently, their suggestions are driven by published literature that uses lab equipment different from those of the gut health companies. Worst still, they do not follow up analysis demonstrating that their suggestions actually work. Ideally, the effectiveness of their AI should be made public with the primary data. This lack of homogeneity is further driven by the quality of scientific facts feeding the recommendation engine, the type of statistical models employed, and how the algorithm processes data to generate leads that cause positive effects on the condition or symptom being addressed. Therefore, results must be validated by clinical outcomes to hold water.

Maintaining a well-balanced diet rich in nutrient-dense foods supports gut health, which plays a crucial role in overall well-being and mental health. Research suggests that a diverse gut microbiome contributes to improved digestion, immunity, and mood regulation. Here are some evidence-based dietary recommendations:

1. Whole, Natural Foods Over Processed Foods: Minimizing processed and packaged foods is essential for gut health, as they often contain artificial additives, preservatives, and high levels of refined sugar, which can disrupt the balance of gut bacteria. Instead, focus on whole, natural foods such as fresh vegetables, fruits, whole grains, and lean proteins. These nutrient-dense foods help maintain a diverse and healthy gut microbiome, which supports digestion and immune function.
2. Fiber-Rich Foods: Dietary fiber acts as food for beneficial gut bacteria and promotes regular digestion. To increase fiber intake, include whole grains like quinoa, brown rice, and whole wheat products. Legumes such as lentils, black beans, and chickpeas are excellent sources of fiber and protein. Nuts and seeds, including almonds, flaxseeds, and chia seeds, also contribute to gut health. Additionally, incorporating fiber-rich vegetables like broccoli, carrots, and Brussels sprouts can further enhance digestive health.
3. Prebiotic Foods: Prebiotics are types of fiber that feed beneficial bacteria in the gut, helping them thrive. Foods naturally rich in prebiotics include bananas, onions, garlic, leeks, asparagus, and Jerusalem artichokes. These foods encourage the growth of good bacteria and improve overall gut function. Incorporating a variety of these prebiotic-rich foods into meals can significantly enhance microbiome diversity.
4. Probiotic Foods: Probiotics are live bacteria that help maintain a healthy balance in the gut. Eating probiotic-rich foods can improve digestion and support immune function. Plain yogurt with live active cultures is a great source of probiotics, but it is important to choose unsweetened varieties to avoid added sugars. Kefir, a fermented dairy product, contains even more probiotics than yogurt and is beneficial for gut health. Other excellent probiotic foods include fermented vegetables such as kimchi and sauerkraut, as well as miso, tempeh, and naturally brewed kombucha.
5. Reducing Sugar and Artificial Sweeteners: Excessive sugar intake can promote the growth of harmful bacteria in the gut and lead to inflammation. Instead of consuming sugary breakfast cereals and flavored yogurts, try adding cinnamon and berries to plain yogurt, oatmeal, or chia pudding for natural sweetness. Artificial sweeteners should also be limited, as some studies suggest they may negatively affect gut bacteria. Choosing whole, naturally sweet foods like fruits can help satisfy cravings while supporting gut health.
6. Fresh Fruits and Vegetables: A diet rich in a variety of colorful fruits and vegetables provides essential vitamins, minerals, and antioxidants that support a healthy gut. Leafy greens such as spinach, kale, and Swiss chard are excellent sources of fiber and beneficial plant compounds. Cruciferous vegetables like broccoli, cauliflower, and cabbage contain sulfur-rich compounds that support gut health. Fruits such as berries, apples, pears, and citrus fruits provide antioxidants and fiber, promoting a well-balanced microbiome.
7. Healthy Proteins: Protein is necessary for overall health, but the type of protein consumed can impact gut bacteria. Lean poultry such as chicken and turkey provide high-quality protein without excessive saturated fats. Fatty fish, like salmon, sardines, and mackerel are rich in omega-3 fatty acids, which help reduce inflammation and support brain and gut health. Plant-based proteins such as tofu, tempeh, beans, and lentils are also excellent sources of gut-friendly nutrients. While red meat can be included in moderation, it is best to choose lean cuts and avoid excessive consumption.
8. Hydration and Herbal Teas: Staying hydrated is crucial for digestion and overall gut health. Drinking plenty of water helps maintain a healthy digestive system by aiding nutrient absorption and waste elimination. Herbal teas such as ginger tea, peppermint tea, and green tea contain natural compounds that support gut health and reduce bloating. Adding herbal teas to your daily routine can help soothe the digestive system and improve gut function.

By adding these gut-friendly foods into your diet, you can enhance digestion, boost immunity, and improve mood, leading to overall better health and well-being. A diverse and nutrient-rich diet is key to maintaining a healthy microbiome and achieving long-term wellness.