This study evaluates the effect of L. reuteri ATCC PTA 6475 supplementation on testosterone in men.

The probiotic Lactobacillus reuteri ATCC PTA 6475 has been shown to modulate testosterone levels in mice. It is not known if these effects are seen in humans and this trial is intended to study this.

The aim of this study is to investigate if L. reuteri ATCC PTA 6475 will effect blood testosterone levels in in healthy male subjects 50-65 years of age.

Inclusion Criteria:

• Willing and able to give signed informed consent for participation in the study.
• Healthy males aged between 50-65 with no known underlying medical conditions
• Subjects who are capable of taking themselves to testing centre at 3 separate timepoints (Baseline, week 6 and week 12).
• Subjects who are available to give fasting blood samples before 10am on day of blood sample collection
• No history of androgen or testosterone supplementation within 6 months prior to study start.
• Subjects who have not been taking antibiotics or probiotic supplements 4 weeks prior to study start 8. Able and willing to comply with the restirictions defined for the study period
• Ability to understand and comply with the requirements of the study, as judged by the investigator physician

Exclusion Criteria:

• Subjects who presently have or have had cardiovascular issues in the past 2 years.
• Subjects who have a Body Mass Index of < 18 or > 30
• Known elevated Prostate Specific Antigen levels.
• History of prostate or testicular cancer.
• Nicotine abuse
• Alcohol abuse