Add spice to your meal... and to your gut microbiota?

Our diet remains the easiest way to modulate the gut microbiota, since the bacteria that colonize the gut feed on undigested food compounds, such as fibers and polyphenols. Such compounds are found in abundance in vegetables. Other polyphenol-rich foods that benefit our gut microbiota are herbs and spices. How exactly do they effect the bacterial composition of the gut?

A randomized (sidenote: Randomized trial Study in which the products tested are distributed randomly, between the participants. ) , controlled (sidenote: Controlled trial a study in which participants are given either a test product (capsule containing the active compound) or a placebo (control capsule not containing the active compound), thus allowing for comparison. ) , double-blind trial (sidenote: Double-blind trial both the participants and the researchers are unaware who has received the test product (capsule containing the active compound) and who has received a placebo (control capsule not containing the active compound). ) conducted on 54 American adults at risk of cardiovascular disease provided the answers. During three successive four-week periods (separated by washout periods of at least two weeks), the participants were fed a classic American diet enriched with a mixture of herbs and spices in various concentrations.

Boosting Ruminococcaceae

The result: this simple mixture modified the participants’ gut flora. Bacterial diversity increased with the dose (higher diversity with 3.3 g/d than with 0.5 g/d) and compared to the initial diversity. However, the latter result should be viewed with caution, since it may be due as much to the change in diet among the participants (who were provided with standardized meals) as to the herb and spice capsules.

The second finding of the study is that meals rich in herbs and spices seem to go hand in hand with a higher presence of beneficial bacteria, primarily from the Ruminococcaceae family. According to a previous study, these bacteria are associated with lower long-term weight gain. The consumption of spices also enriched the Agathobacter genus and the bacterium Faecalibacterium, which produce short-chain fatty acids (sidenote: Short chain fatty acids (SCFA) Short chain fatty acids (SCFA) are a source of energy (fuel) for an individual’s cells. They interact with the immune system and are involved in communication between the intestine and the brain. Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front Endocrinol (Lausanne). 2020;11:25. ) , such as butyrate and propionic acid, whose benefits include their anti-inflammatory effects.

Do spices naturally boost a gut microbiota beneficial to our health? This avenue needs to be explored further. In the meantime, add some herbs and spices to your menu...