This positive effect is in part thanks to activity in the gut. In fact, some scientists call the gut ‘the second brain’ because the two organs work so closely together. The dietary fibre in the food we eat is central to good gut health. Macadamia nuts are around 7% total fibre and some of that fibre is prebiotic fibre which acts as food for the microflora (bacteria and fungi) in the gut.
The gut microflora ferment this prebiotic fibre, producing short chain fatty acid gases that have positive effects on the creation of the ‘happy hormone’ serotonin. In fact, around 90% of serotonin is actually produced in your gut. By feeding your gut bacteria with the prebiotic fibres present in macadamias and other nuts, you are stimulating a healthy colony of gut bacteria to aid this serotonin-producing process.30,31