Most of us know that our guts are packed with millions of bacteria and that these produce different neurochemicals our brains use to learn, remember and regulate mood. That’s what the gut-brain axis is all about. But what many of us may be less familiar with is the fact that our gut actually produces the chemicals that make us feel good.

Think about it for a moment: can you remember a breakfast, for example, that left you feeling really satisfied and happy? It might have been a big bowl of oats with nut butter, fruits and yoghurt. Or it could have been a few slices of chunky sourdough with marmite. Less fibrous breakfasts may be delicious but a croissant rarely leaves you feeling super-content.

It’s the same when you’ve spent a few days eating mainly beige foods. After a while, you start to feel grey inside. You might be constipated and bloated – and those physical feelings can often come with feeling irritable, listless and distracted. While those could be side effects of being overly gassy, it’s also likely that they’re caused by disrupted serotonin production.

Mental health advocate Dr Taylor Marae is a registered dietitian who shares content about health anxiety on Instagram, and she’s been celebrating the explosion of research into the role of the gut on mental health. “As a registered dietitian who’s been focused on functional nutrition and holistic healing since the beginning of my career, I scream this from the rooftops,” she writes of gut-based serotonin production. “We can heal so much inside of us, and yes, our mind too – the gut-brain connection is so real.”

How to eat yourself happy: 95% of serotonin is made in the gut