Starch rich diets can influence the gut microbiota and subsequently behavior, researchers are reporting.
By Sofia Popov
Research has increasingly recognized the gut microbiota as a major determinant of behaviour, owing to its role in the modulation of the gut-brain axis. In humans, and in animal models, studies have shown that specific bacterial taxa are linked to - even going so far as to induce changes in - cognitive states, including anxiety and anxiety-like behavior. For instance, anxiety-like behavior was seen in mice introduced Campylobacter jejuni, who also did not demonstrate a detectable visible immune response. Similarly, other studies have shown the microbiome can influence brain development and neurobehavioral issues.
Studies have shown that specific bacterial taxa are linked to - even going so far as to induce changes in - cognitive states, including anxiety and anxiety-like behavior.
Modulation of the gut microbiota has traditionally been investigated through bacterial administration (i.e. probiotics) or via complete transfer (i.e. fecal microbial transplantation.) Yet, numerous studies have demonstrated that dietary modulation can induce changes in the composition and species diversity of the gut microbiota, such that diet may be a more universal and easily implemented means of modulating the microbiota. In particular, resistant starch has received attention, owing to its beneficial impact on health, as these low-digestible carbohydrates are fermented, and not digested, by resident microbiota to produce various beneficial metabolites. Most recently, researchers have investigated whether diets rich in resistant starches were also associated with behavioural changes.
Diet may be a more universal and easily implemented means of modulating the microbiota.
Mice were randomly separated into 3 different groups, based on different diets: for 6 weeks, they were either fed a normal corn diet, a resistant starch (RS) diet or an octenyl-succinate (OS) diet. At the same time, the animalsâ€™ participated in robust behavioral tests, whilst their weight and the composition of their microbiota were monitored. The researchers found that there were similar weight gains for the resistant starch and normal corn diet, whilst the OS group had lower weight gains. Meanwhile, fecal microbiota analyses revealed that the RS-supplemented diet altered the microbiota composition, as well as influence brain function, which was reflected through the rise in anxiety-related behaviors. Namely, the RS-group depicted increases in Verrucomicrobia and Actinobacteria compared to the other groups, respectively. Meanwhile, all mice exhibited significant anxiety-like-behaviour in an Elevated Plus Maze, which consisted of a plus shaped apparatus of two arms closed by black Plexiglas walls. For the open-field tests, it was mice on the RS and OS diets that displayed high anxiety-like behaviors.
Fecal microbiota analyses revealed that the RS-supplemented diet altered the microbiota composition, as well as influence brain function, which was reflected through the rise in anxiety-related behaviors.
Studies in humans continue to demonstrate that the composition of the gut microbiota can carry dramatic influences on an individualâ€™s behavior: such as, in patients suffering Inflammatory Bowel Disease, who are known to experience anxiety and depression. Overall, this data adds to such previous research, drawing on the noted influence of dietary manipulation on behaviour, and the effects starch-rich diets can have, through modulation of the gut-brain axis, in inducing undesirable behavioural effects. Thus, this could potentially counteract the benefits of microbial fermentation.
This data adds to previous research, drawing on the noted influence of dietary manipulation on behaviour.
Microbiota modulation is emerging as a potential therapeutic modality that has the power to influence behavior and, thus, improve quality of life. Targeting diet through RS represents a potential option for selecting a specific microbiome to obtain desired neurological outcomes. Moreover, given their high compliance and low-cost, dietary interventions are appealing, compared to the use of pharmaceuticals. This current study reinforces that RS is effective for changing taxonomy in the gut microbiota, whilst it also reveals the influential potential of RS on behavior.
Microbiota modulation is emerging as a potential therapeutic modality that has the power to influence behavior and, thus, improve quality of life.
Looking onwards, these results underscore the necessity to consider the effect potential types of RS can have on inducing anxiety-like behaviours, which, in turn, carries practical applications when defining experiments investigating the impact of digestion-RS to benefit health outcomes.
Lyte M., et al. Resistant Starch Alters the Microbiota-Gut Brain Axis: Implications for Dietary Modulation of Behavior. PLOS ONE; 11(1):e0146406 (2016). DOI: 10.1371/journal.pone.0146406