In recent times, interest in the interaction effects between the gut microbiome and the brain increased massively. This is not a surprise considering that since the Covid-19 pandemic hit the earth, it has had a major effect on our lives, leading to challenging situations. As stress increases, conditions related to brain health, such as loss of concentration, sleep deprivation, fatigue, and depression, are on the rise too (1).

It is well-known that dietary patterns are closely related to brain health and that specific food component might positively affect our brain. Take, for example, chocolate – known to boost the production of endorphins, better known as the ‘feel-good’ chemical of your brain. The exciting molecules associated with this beneficial effect are flavonoids, which are also contained in citrus fruits in a large amount.

It is known that citrus flavonoids are associated with positive gut microbiome modulation (2). Additionally, the gut microbiome can activate the gut-brain axis by increasing serotonin synthesis, an endorphin in the body that makes you feel happy (3).

The study.

Currently, research is trying to reveal how the gut microbiome composition plays a role in this mechanism and supports brain health. Interestingly, a new study assessed the effects of flavonoids present in orange juice,  the gut microbiome composition, and how it relates to brain health (4). In this study, scientists gave one group flavonoid-rich orange juice (FR) and another group flavonoid-low orange juice (FL) for 8 weeks. 

The results show that the composition in the gut microbiota was changed after the intervention. This was done by analysing stool samples of participants (N = 40). It was found that a high intake of flavonoids changed the relative abundance of the gut microbiome, especially the Lachnospiraceae family. These bacteria are known to break down non-digestible carbohydrates into short-chain fatty acids (SCFAs). Furthermore, the Lachnospiraceae family is known to produce a beneficial SCFA called butyrate. SCFAs aid in the strengthening of gut barrier function and regulating immune homeostasis. Remarkably, they are also involved in neurotransmitter production (like serotonin and GABA) and neuroprotection and can penetrate the blood-brain barrier. The Lachnospiraceae family increase was positively correlated with an increase in Brain-Derived Neurotrophic Factor (BDNF), a neurotrophin that performs multiple central nervous system functions related to brain health.

In conclusion, although the association between flavonoids from citrus and brain health is still unclear, it is suggested that the flavonoids in oranges may be functional to our brain by altering the gut microbiome and increasing butyrate-producing bacteria. 


1. Bueno-Notivol, J., Gracia-García, P., Olaya, B., Lasheras, I., López-Antón, R., & Santabárbara, J. (2021). Prevalence of depression during the COVID-19 outbreak: A meta-analysis of community-based studies. International Journal of Clinical and Health Psychology, 21(1), 100196. doi:

2. Stevens, Y., Rymenant, E. V., Grootaert, C., Camp, J. V., Possemiers, S., Masclee, A., & Jonkers, D. (2019). The intestinal fate of citrus flavanones and their effects on gastrointestinal health. Nutrients, 11(7), 1464. 

3. O’Mahony, S. M., Clarke, G., Borre, Y., Dinan, T., & Cryan, J. (2015). Serotonin, tryptophan metabolism and the brain-gut-microbiome axis. Behavioural brain research, 277, 32-48. 

4. Park, M., Choi, J., & Lee, H. J. (2020). Flavonoid-Rich Orange Juice Intake and Altered Gut Microbiome in Young Adults with Depressive Symptom: A Randomized Controlled Study. Nutrients, 12(6). doi:10.3390/nu12061815

At Bioactor we love citrus flavonoids. This is why, we developed MicrobiomeX®, a first-in-class citrus extract that leverages the gut microbiome’s potential.