Casein and probiotics for aerobic fitness in male soccer players
What it found
Taking 20 grams of casein with probiotics improved how long male soccer players could exercise before tiring, compared to a placebo.
Taking casein alone did not clearly beat the placebo for this measure.
What they found
Studies in people
Casein plus probiotics
Players taking both casein and probiotics lasted longer on the treadmill before getting tired than those taking the placebo. Their breathing compensation point also improved more than the placebo group. These were measured in people.
Casein alone
Taking 20 grams of casein alone did not significantly change how long players lasted on the treadmill compared to the placebo. However, it did improve one specific breathing measurement compared to the placebo. These were measured in people.
Probiotics alone
Taking only the probiotic capsule did not lead to clear improvements over the placebo when comparing the groups directly. But within their own group, these players did last longer on the treadmill than before they started. These were measured in people.
Maximum oxygen use
All three supplement groups used more oxygen at peak effort compared to their own starting points. But when compared directly to the placebo group, there was no clear difference between them. These were measured in people.
What the authors conclude
- They found that taking probiotics and casein together improved aerobic fitness measures in male soccer players more than taking either alone.
- The authors suggest that soccer players add probiotic and casein supplements to their diets to help with endurance performance.
How it was done
Soccer involves intense running and matches lasting over 90 minutes, so nutrition matters for performance and recovery. The authors wanted to see if gut bacteria supplements combined with casein protein could improve players' aerobic fitness.
They studied 44 male soccer players for four weeks. Players took either a probiotic capsule, 20 grams of casein powder before bed, both together, or a starch placebo, three times a week on training days. They ran treadmill tests before and after to measure their aerobic capacity.
What it can’t tell you
- This trial only included young male soccer players, so the results might not apply to women, older adults, or people who do not play sports.
- The study lasted four weeks, so scientists do not yet know what happens if someone takes these supplements for months or years.
- Because the researchers could not give a separate placebo for the casein powder, it is harder to be certain about the effects of casein taken by itself.
Who paid
- Conflicts
- No potential conflict of interest was reported by the author(s).
- Authors work at
- Shiraz University, Iran
The paper
- Title
- The effect of probiotics and casein supplementation on aerobic capacity parameters of male soccer players
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Imanian B, Hemmatinafar M, Daryanoosh F, et al (2024). The effect of probiotics and casein supplementation on aerobic capacity parameters of male soccer players. Journal of the International Society of Sports Nutrition. doi:10.1080/15502783.2024.2382165Free full textPubMed 39039903DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error