Elite athletes perform better with high carbohydrate rather than high protein diets

The study found that in those following a high-protein regime, this resulted in a disturbance in the stability of the gut microbiome.

[August 13, 2022: Jamie Forsyth, Anglia Ruskin University]

Researchers from across the UK analysed the performance and gut health of a group of well-matched, highly trained endurance runners (CREDIT: Creative Commons)

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.


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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%.

Illustrates longitudinal subject performance during the Max SE trial. Each point represents an individual subject through preintervention (pre), midintervention (mid), and postintervention (post), sampling time points, colored by intervention group (HCD = blue; HPD = pink). The line represents best fit of the linear regression model based on all subjects at that time point. The shaded area describes the 95% confidence intervals of the linear model.

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.

There were certainly changes to the gut microbiome following a short-term high-protein diet which appeared to be associated with performance. (CREDIT: NHGRI)

“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.


Note: Materials provided above by Anglia Ruskin University. Content may be edited for style and length.

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Joshua Shavit
Joshua ShavitScience and Good News Writer
Joshua Shavit is a bright and enthusiastic 17-year-old student with a passion for sharing positive stories that uplift and inspire. With a flair for writing and a deep appreciation for the beauty of human kindness, Joshua has embarked on a journey to spotlight the good news that happens around the world daily. His youthful perspective and genuine interest in spreading positivity make him a promising writer and co-founder at The Brighter Side of News.