Summary: Short-term high-protein diets were associated with gut microbial instability that appears to hinder elite athletes’ performances.
Source: Anglia Ruskin University
New research has found that microbial instability in the gut could hinder the performance of elite endurance athletes, and that short-term, high-protein diets are associated with this type of imbalance.
Researchers from across the UK analysed the performance and gut health of a group of well-matched, highly trained endurance runners, to explore the impact of both high-protein and high-carbohydrate diets.
The study found that in those following a high-protein regime, this resulted in a disturbance in the stability of the gut microbiome. This was also accompanied by a 23.3% reduction in time trial performance.
Analysis found a significantly reduced diversity and altered composition of the gut phageome, as well as higher levels of certain types of virals and bacterial compartments. Those participants whose gut microbiome was more stable performed better during time trials.
Gut imbalance impacts different people in different ways, but can manifest itself in acute symptoms such as cramps or nausea. As there is cross-talk between the gut and the brain, authors suggest this could be important.
Those following a high-carbohydrate diet resulted in an improved time trial performance of 6.5%.
Dr Justin Roberts, Associate Professor in Health and Exercise Nutrition at Anglia Ruskin University (ARU) and co-author of the study, said: “These results suggest that athletic performance may be linked with gut microbial stability, where athletes who had more stable microbial communities consistently performed best in each dietary intervention compared to those with a more turbulent gut microbiota.
“While we cannot be certain that the high amount of protein in the body was entirely responsible for the significant drop in time-trial performance, it was found that there were certainly changes to the gut microbiome following a short-term high-protein diet which appeared to be associated with performance.
“These results suggest that consuming a high-protein diet may negatively impact the gut via an altered microbial pattern, while a high-carbohydrate intake, for example containing a variety of grains and vegetables, was associated with greater gut microbial stability.
“The diets were well controlled and carefully balanced and so we think it is unlikely that the protein itself caused a drop in performance. Instead we think it is possible that the changes to the gut microbiome could impact intestinal permeability or nutrient absorbtion, or the messages between the gut and the brain, affecting perceived effort and therefore performance.”
The study was published in the American Society for Microbiology’s journal mSystems and was carried out by researchers from Northumbria University, Anglia Ruskin University (ARU), University of Reading, Newcastle University, University of Kent, University of Hertfordshire and Northwest University in South Africa.
Gut Microbial Stability is Associated with Greater Endurance Performance in Athletes Undertaking Dietary Periodization
Dietary manipulation with high-protein or high-carbohydrate content are frequently employed during elite athletic training, aiming to enhance athletic performance. Such interventions are likely to impact upon gut microbial content.
This study explored the impact of acute high-protein or high-carbohydrate diets on measured endurance performance and associated gut microbial community changes.
In a cohort of well-matched, highly trained endurance runners, we measured performance outcomes, as well as gut bacterial, viral (FVP), and bacteriophage (IV) communities in a double-blind, repeated-measures design randomized control trial (RCT) to explore the impact of dietary intervention with either high-protein or high-carbohydrate content.
High-dietary carbohydrate improved time-trial performance by +6.5% (P < 0.03) and was associated with expansion of Ruminococcus and Collinsella bacterial spp.
Conversely, high dietary protein led to a reduction in performance by −23.3% (P = 0.001). This impact was accompanied by significantly reduced diversity (IV: P = 0.04) and altered composition (IV and FVP: P = 0.02) of the gut phageome as well as enrichment of both free and inducible Sk1virus and Leuconostoc bacterial populations.
Greatest performance during dietary modification was observed in participants with less substantial shifts in community composition. Gut microbial stability during acute dietary periodization was associated with greater athletic performance in this highly trained, well-matched cohort.
Athletes, and those supporting them, should be mindful of the potential consequences of dietary manipulation on gut flora and implications for performance, and periodize appropriately.