Could a daily probiotic boost sperm health in men over 40?
NCT ID NCT06544278
First seen Aug 03, 2026 · Last updated Aug 07, 2026 · Updated 2 times
Summary
This trial tests whether a daily probiotic supplement containing Bifidobacterium longum BL21 can improve sperm quality in men aged 40 to 59. Over 8 weeks, participants take either the probiotic or a placebo, and researchers measure changes in sperm motility, hormone levels, and other markers. The goal is to see if this simple supplement could support male fertility in middle age.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- probiotic product containing Bifidobacterium longum subsp. longum BL21
- What this could lead to
- If effective, this probiotic could offer a simple, non-prescription option to support sperm health in middle-aged men.
- What could go wrong
- This is a small, early-stage trial with only 40 participants, so results may not apply broadly. Probiotics are generally safe, but individual responses can vary.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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40 people
The number who actually took part.
- Started
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Aug 2024
- Finished
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Jun 2025
- Lead sponsor
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A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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40 to 59 years
- Sex
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Male participants only
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 1. Subjects aged 40-59 years old. 2. Normal levels of gonadotropins, testosterone, and serum prolactin. 3. No use of other traditional Chinese and Western medicines for oligoasthenoteratozoospermia treatment in the past 3 months. 4. Patients who can understand the clinical study and commit to complying with the study requirements and procedures. 5. Patients who have signed the informed consent form and are able to complete the study as per the trial protocol. Exclusion Criteria: 1. Organic lesions of the reproductive system; 2. Use of antibiotics in the two weeks prior to recruitment; 3. Sexual dysfunctions such as erectile dysfunction, ejaculatory abnormalities, preventing completion of sexual intercourse; 4. Genitourinary infections, such as Chlamydia or Mycoplasma infections; 5. Abnormal sex hormone levels; 6. Obesity (BMI greater than 28); 7. History of allergies to the probiotic preparations used in this study; 8. Severe cardiovascular or cerebrovascular diseases, liver or kidney dysfunction, hematologic disorders, psychiatric illnesses, or other severe comorbidities; 9. Use of medications in the past 3 months that may affect the trial; 10. According to the investigator's judgment, the subject's condition does not qualify them for participation in the study.
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As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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Qilu Hospital of Shangdong University
Jinan, Shangdong, 250012, China
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