Marlene Watson-Tara | author of Go Vegan
If you’ve ever felt your stomach drop before bad news, you already understand the gut-brain connection—even if you’ve never said the words out loud. Marlene Watson-Tara, author of Go Vegan and co-founder of the Human Ecology Project, is shining a bright light on how our daily food choices can influence mental state, mood, and stress. Not as a miracle cure, not as a moral sermon—just as a practical lever most of us can actually pull before the day pulls us.
Mental health is rightly everywhere in the headlines, and for good reason. There’s rarely one neat cause. Life can land a series of body blows—bereavement, illness, losing a home, losing a job, or simply carrying a thousand “small” pressures that add up to something heavy. And sometimes, frustratingly, the why is unclear.
But one factor that often sits on the sidelines of the conversation is diet. Watson-Tara’s argument is simple: if we understand what certain foods do to the digestive system, we can make choices that are less likely to aggravate symptoms we’re already battling.
The gut-brain link: a “new” field with old clues
Research into the gut-brain connection is often described as new and fascinating—and it is—but the body has been dropping hints for a long time. The gut-brain relationship is now recognised as a basic tenet of physiology and medicine, with growing evidence that gastrointestinal health is involved in a variety of neurological diseases.
What’s particularly eye-opening is how gut bacteria may influence psychology and behaviour, not just digestion. The gut and brain are created from the same type of tissue, Watson-Tara notes, and each can influence the other. They communicate through shared pathways and nerves, operating less like separate departments and more like a single organisation with two head offices.
And then comes the line that tends to stop people mid-sentence: the gut can be perceived as our “second brain”.
It’s not poetic licence. The gut contains the same neurotransmitters and as many neurons as the spinal cord and peripheral nerves. It also holds almost 95% of the body’s serotonin—the neurotransmitter linked with mood and social behaviour, appetite and digestion, sleep, memory, and sexual desire and function. In plain English: if your gut is struggling, your mind may notice.
Depression, disability, and the inflammation angle
According to the World Health Organisation, more than 264 million people of all ages suffer from depression. It remains one of the leading causes of disability worldwide and a major contributor to the global burden of disease.
Watson-Tara points to a crucial theme running through modern findings on the gut-brain connection: inflammation. Dr. Michael Greger explains that the relationship between mental health and gut inflammation was first noted in 1887. The doctor who discovered this relationship was Julius Wager-Jauregg, the only psychiatrist to have ever won the Nobel Prize, with subsequent studies confirming the link.
The contemporary concern is that the modern diet is pro-inflammatory. That inflammation can irritate the vagus nerve—the direct connection between gut and brain—potentially influencing mood and stress responses. The mechanism has been detailed in multiple studies, including work referenced in the Journal of Neuroscience Research, with consistent outcomes.
The “usual suspects” on the plate
The gut biome—those colonies of microorganisms living in the digestive tract—can be affected by what we eat. Watson-Tara flags common culprits in mainstream modern diets that may exacerbate inflammation and disrupt gut balance.
Foods most associated with increased inflammation in this framework include: simple sugars, fructose, dairy foods, eggs, alcohol, meat, hydrogenated fats, palm oil and some fruits and vegetables such as tomato and pineapple.
If there’s already inflammation in the body, these foods may feed the process further—making the gut-brain connection more than a theory, and more like a daily feedback loop.
What the data suggests about CRP and stress
One marker that often comes up in inflammation conversations is C-reactive protein (CRP). Using data from two large studies, Danish researchers have found that higher blood levels of C-reactive protein (CRP) are associated with a greater risk of psychological stress and clinical depression.
Watson-Tara also notes that diets high in animal protein can trigger a burst of inflammation—something that may be particularly unhelpful for someone already experiencing depressive symptoms. Conversely, diets rich in antioxidants—typically plant-forward patterns—are presented as having a meaningful benefit for stress reduction.
Here’s the practical upside: the gut biome changes with diet. Watson-Tara highlights that a plant-based diet can cut the C-reactive protein by 30% within two weeks, attributed to the anti-inflammatory properties of antioxidants.
That matters because clinical depression can be accompanied by increased oxidative stress and the autoimmune inflammatory responses it creates—conditions where calming inflammation may be a sensible part of broader support.
Fermented foods: old-school staples, modern missing piece
If the modern diet is a loud band with the amps turned up, fermented foods are the quiet professionals who show up early, do the work, and leave without demanding applause. Watson-Tara notes that fermented foods were traditional staples in many cultures, but modern food manufacturing has removed many of them from everyday eating.
Traditionally fermented options she points to include miso soup, tempeh, naturally fermented soy sauce or sauerkraut—foods commonly used to support a healthy gut biome.
And because the gut-brain connection is partly about communication—signals travelling between digestive tract and nervous system—supporting digestion isn’t just about comfort. It may also be about clarity, steadier mood, and resilience under stress.
Why plant-based eating keeps coming up
Watson-Tara argues that going vegan has multiple proven benefits, and one reason is fibre. An exclusively plant-based diet is naturally higher in fibre and can boost bacteria that make short-chain fatty acids (SCFAs).
Those SCFAs are credited with broad effects: improving immunity against pathogens, providing an energy source for the gut lining, helping maintain the blood-brain barrier, activating critical intestinal protection mechanisms, and supporting blood sugar regulation and caloric intake control.
Not exactly headline-grabbing at a dinner party, but then again, neither is feeling wired, tired, anxious, and flat all at once.
Practical takeaways (without turning your kitchen into a laboratory)
If you’re looking to support mental wellbeing through the lens of the gut-brain connection, Watson-Tara’s themes translate into straightforward habits:
- Prioritise fibre-rich plant foods to support a diverse gut biome
- Reduce heavily processed foods that may promote inflammation
- Add traditionally fermented foods where tolerated
- Think in patterns, not perfection—small changes can still shift the gut environment
None of this replaces professional mental health care. But it may complement it—especially for those who feel they’ve tried everything, except the thing they do three times a day.
Eat well and stay healthy.
