Plain language summary
Protein supplements are popular among athletes to improve performance and increase muscle mass. However, their effect on other aspects of health is less well known. Dietary changes can affect gut microbiota balance, with beneficial or harmful consequences for the host. This small pilot study was performed on cross-country runners whose diets were complemented with a protein supplement (whey isolate and beef hydrolysate) or maltodextrin (control) for 10 weeks. Microbiota, water content, pH, ammonia, and short-chain fatty acids (SCFAs) were analysed in faecal samples, and oxidative stress markers were measured in blood plasma and urine. Faecal pH, water content, ammonia, and SCFA concentrations did not change, indicating that protein supplementation did not increase the presence of these metabolites of fermentation. Similarly, it had no impact on plasma or urine malondialdehyde levels. Protein supplementation did however increase the abundance of the Bacteroidetes phylum and decrease the presence of health-related taxa including Roseburia, Blautia, and Bifidobacterium longum. The authors concluded that long-term protein supplementation may have a negative impact on gut microbiota. Further research is needed to establish the impact of protein supplements on gut microbiota.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Long-term protein supplementation may have a negative impact on gut microbiota.
- Further research is needed to establish the impact of protein supplements on gut microbiota and whether there is a differential impact between protein from animal and plant sources.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
This is a very interesting study that is relevant to athletic populations.
Clinical practice applications:
Potentially there is a role for probiotics / prebiotics when increasing protein intake (particularly of animal origin) to maintain microbiota diversity and prevent ensuing health complications.
Considerations for future research:
Further, larger scale, research is needed to understand whether the same effect of protein supplementation would be seen with plant-based proteins or whether this is unique to animal based protein supplementation. For example, is the hydrolysation of the proteins to account for the largest effect or could a whole food protein, i.e. not hydrolysed, elicit the same effects?
Also, is this effect seen in other sports, e.g. non-endurance. What about the effect under different conditions e.g. energy deficit vs. energy excess?
Abstract
Nutritional supplements are popular among athletes to improve performance and physical recovery. Protein supplements fulfill this function by improving performance and increasing muscle mass; however, their effect on other organs or systems is less well known. Diet alterations can induce gut microbiota imbalance, with beneficial or deleterious consequences for the host. To test this, we performed a randomized pilot study in cross-country runners whose diets were complemented with a protein supplement (whey isolate and beef hydrolysate) (n = 12) or maltodextrin (control) (n = 12) for 10 weeks. Microbiota, water content, pH, ammonia, and short-chain fatty acids (SCFAs) were analyzed in fecal samples, whereas malondialdehyde levels (oxidative stress marker) were determined in plasma and urine. Fecal pH, water content, ammonia, and SCFA concentrations did not change, indicating that protein supplementation did not increase the presence of these fermentation-derived metabolites. Similarly, it had no impact on plasma or urine malondialdehyde levels; however, it increased the abundance of the Bacteroidetes phylum and decreased the presence of health-related taxa including Roseburia, Blautia, and Bifidobacterium longum. Thus, long-term protein supplementation may have a negative impact on gut microbiota. Further research is needed to establish the impact of protein supplements on gut microbiota.
Methodological quality
Allocation concealment
:
Yes
