The connection between the brain and gut is an ongoing and an extensive topic of research. Did you know that the longest nerve in the human body, the Vagus Nerve, connects the gut and the brain? The gut has also been called the ‘second brain’ because it produces many of the same neurotransmitters as the brain, like serotonin, dopamine and gamma-aminobutyric acid, all of which play a key role in regulating mood. Our mood is also largely linked to our diet, validating the brain and gut relationship further. (1)
Studies show us that dietary factors can affect multiple brain processes by regulating neurotransmitter pathways, synaptic transmission, membrane fluidity and signal-transduction pathways. For instance, a diet rich in omega-3 fatty acids is shown to upregulate or stimulate the genes that are important for maintaining the synaptic function and plasticity of the neurons. Similarly, saturated fatty acids have the opposite effect, as they are shown to reduce molecular substrates that support cognitive processing and increasing the risk of neurological dysfunction in both humans and animals. (2)
So which nutrients correlate to our mental health and help us maintain a healthy brain function?
Impact of Nutrients in Cognitive Health
- Omega-3 Fatty Acids: These are essential fatty acids which are not produced within the body and hence, have to be consumed through diet. Omega-3 fatty acids provide fluidity to the brain and play key roles in cell signalling. Clinical trials have indicated omega-3 fatty acids to have lower depression scores, particularly DHA. (2)
- Folate (Vitamin B9): Folate supplementation either by itself or in conjunction with other B-vitamins, was seen to have potential effects in preventing cognitive decline, dementia during aging and has similar effects as that of anti-depressants.
- Vitamin B6: Pyridoxine is another such B-vitamin that helps to boost the neurotransmitters dopamine and serotonin.
- Iron: Deficiency of iron can lead to fatigue, laziness and mood disorders. Research shows that most people show improvements in mood after supplementing with iron.
- Fiber: Fermentable fibers act as food for the gut microbiome which in turn have its own mental health benefits. Dark green leafy vegetables contain higher amounts of prebiotics which support the gut micorflora.
- Flavanols: Dark chocolate is great when considering the effects of flavanols on cognition. It helps boost blood flow to the brain and reduce inflammation, which plays a role in mood regulation.
- Probiotics: Recent scientific research is proposing a new category of medicines called ‘psychobiotics’ which is hoped to have attributes like anti-inflammatory, antidepressant and anti-anxiety constitutes. A research where participants with Alzheimer’s were given 4 specific strains of probiotics for 12 weeks scored better on a test to measure cognitive impairment compared to placebo. Similar studies of adding probiotic enriched food in women’s diet were shown to stimulate calmer states in these individuals. (1)
Role of Serotonin
Serotonin is a neurotransmitter functioning as a mood stabilizer which modulates most human behavior. It is estimated that 90% of serotonin is produced in the gut. It is synthesized from the essential amino acid tryptophan. Tryptophan has to be consumed through the diet, a deficiency of tryptophan leads to lower levels of serotonin. This may result in anxiety, depression and other mood disturbances.
Although many animal and dairy products contain tryptophan, plant-based foods rich in tryptophan also contain abundant amounts of carbohydrates and antioxidants. This assists the assimilation of the amino acid in the brain helping it across the blood-brain barrier. Some foods sources of tryptophan include nuts, seeds, soy and soy products, peas, beans, lentils, oats, wheat germ, bananas, pineapples spinach and other leafy greens.
Dietary choices and patterns affect both short-term and long-term mental and cognitive health. The biochemicals in the food interact with hormones and neurotransmitters involved in various pathways that modulate mood and behaviour. Thus, having the right balance and eliminating the risk of deficiencies through a well-balanced diet and supplementation is important to support mental wellbeing.
Apart from the macro and micronutrients, certain phytonutrients that boost cognitive function are Ashwagandha root extract, L-theanine and Caffeine in moderation.
- Probiotics may help boost mood and cognitive function, Mind & Mood. June 8, 2019. Harvard Health Publishing. https://www.health.harvard.edu/mind-and-mood/probiotics-may-help-boost-mood-and-cognitive-function
- Gómez-Pinilla, F. (2008). Brain foods: the effects of nutrients on brain function. Nature reviews neuroscience, 9(7), 568-578.
- Spencer, S. J., Korosi, A., Layé, S., Shukitt-Hale, B., & Barrientos, R. M. (2017). Food for thought: how nutrition impacts cognition and emotion. npj Science of Food, 1(1), 1-8