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Interview with Dr. Tara Swart

Symprove spotlight series

Reading time: 3 minutes

Dr. Tara Swart

Tara Swart is a neuroscientist, psychiatrist, bestselling author, executive advisor and senior lecturer at MIT Sloan.

Hi Tara, thank you for joining us. You have an incredible number of accolades to your name, including a bestselling book The Source. What motivated you to write it ?


The Source merges science and spirituality to explain how the way that we feel, think and behave comes from our brain, and that all the things we want (like health, happiness, good relationships, and a feeling of abundance rather than a lack of) depend upon the brain being in an optimal condition so that we can reach our potential in life.

I wanted everyone to understand how amazing their brain is and how to get most out of it. We are complex, adaptive organisms and I felt that neuroplasticity (the incredible ability of our brains to change and grow throughout life) combined with ancient philosophies, in a practical and non-secular way, could offer hope and motivation.


Could you describe the meaning behind the title/phrase ‘the source’?

My definition of ‘the source’ is literally your brain firing on all cylinders so that you can live the best life possible for you. There is also a spiritual element to the usage of the word ‘source’ which is about introspection and tapping into our collective unconscious. I love the idea of our individual success being linked to other people and to the planet.


Many of us have heard of the phrase ‘go with your gut’ or ‘gut feeling’ when making decisions. Is any evidence behind this saying?

We store information in our nervous system through a process called Hebbian learning, named after the neuroscientist Donald Hebb. Our working memory is stored in the outer cortex of the brain, whilst emotions and intuitions are deeper within the limbic system (which is where the neural input from the gut connects to). Our reflexes (an action that is performed without conscious thought as a response to a stimulus) are stored in the brainstem, whilst life experiences, wisdom and patterns are stored in neurons throughout the body, particularly within the gut, which is where the term ‘gut feeling’ comes from. When you have a ‘gut instinct’ it relates to your nervous system recognising a pattern that you may have felt before.


The ‘gut-brain axis’ is a well recognised biochemical signaling pathway. Could you briefly explain the physiology behind this?

The neurons throughout the gut are connected to the brain via the autonomic nervous system. The two-way communication between the brain and the gut is a complex system, largely governed by the vagus nerve, which is part of the parasympathetic (rest/digest) system. There is also a sympathetic nervous system (fright/flight), endocrine (hormonal), and immune components. It’s an incredibly sophisticated and dynamic system.


Are we able to improve our cognition and brain performance through diet?

Our brain only weighs 2-3kg. However, it is the most metabolically active organ in the body, using approximately 20-30% of the energy from our diet. Deficiencies of certain vitamins, minerals and micronutrients can cause brain and mental health issues. Due to the composition of the brain itself, we can classify foods for brain health in a few categories:

  • Good fats such as omega 3s found in oily fish, eggs, avocado, olive oil, nuts and seeds
  • Hydrating foods such as leafy greens, salads, and fruit like melons
  • Antioxidants, anthocyanins and polyphenols found in dark-coloured foods such as aubergine, purple sprouting broccoli, blueberries, dark chocolate and organic coffee

Is there a relationship between our gut microbiome and cognitive function?

The gut microbiome communicates with the gut neurons and the brain through cytokine transmission (chemical messengers which cross the blood-brain barrier). If the quality and diversity of our gut microbiome is compromised, it can negatively affect cognitive function. Equally if we are very stressed or depressed this can affect gut health and the gut microbiome.

If people have an overgrowth of unwanted bacteria in the gut, the microbes release LPS proteins, which drive up inflammation and are detrimental to our health, including our mental well-being. Elevated levels of these proteins have been linked to the development of conditions such as Parkinson’s and dementia and also affect the amygdala (fear centre in the brain). This can heighten feelings of anxiety and increase our chances of experiencing mood disorders. Interestingly, taking a high-quality probiotic for one month has been shown to reduce negative thinking and cognitive reactivity to low mood.


Does sleep also play an important role in the gut-brain axis? How so?

Just like humans, gut bacteria have circadian rhythms that are sensitive to light/darkness, sleep patterns, mealtimes, and regularity of bowels. Regular sleep and wake times, as well as sufficient length and quality of sleep helps to keep our gut microbiome healthy. We must get at least 7-8 hours to allow the overnight cleansing of the brain via the glymphatic system, which flushes out toxins like beta amyloid as the cerebrospinal fluid moves through channels around brain cells during sleep.


Are there any “everyday” changes that you would recommend for improving brain performance?

It’s about making sure we are eating a sufficiently balanced, nutrition-dense, non-processed diet. I believe in eating a healthy, balanced diet containing lots of natural pre- and probiotic foods. In addition:

  • Get good quality sleep
  • Try to do 150 minutes of exercise per week
  • Drink more water
  • Meditate
  • Have positive, meaningful, social relationships

Do you have any recommendations for future research relating to the gut microbiome and neuroscience?

I think that the faecal transplant studies will be illuminating in terms of how the gut microbiota can impact things like mental illness, brain performance and degenerative disease.