A Crossover Clinical Trial Investigating the Effects of Geranylgeraniol (GG) Supplementation on Testosterone Levels in Healthy Men and Women Over an 18-week Period

April 29, 2026 updated by: Michael Jurgelewicz, Designs for Health

The primary purpose of this study is to investigate the effects of geranylgeraniol (GG) supplementation on testosterone levels in middle-aged (40 to 65 years) healthy men and women.

The research team hypothesizes that geranylgeraniol (GG) supplementation will enhance testosterone levels and improve self-reported health outcomes in a healthy population.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The proposed study is an 18-week crossover, placebo-controlled pilot study of GG supplementation or placebo. All study outcomes will be measured at baseline (the beginning of the first week) and at the conclusion of the first 8-week period. This will be followed by a 2-week washout period; study procedures will be repeated with the second intervention for an additional 8 weeks. Outcomes will be assessed at the beginning of this period, and the end, in the same manner as for the first 8-week block.

All participants will receive a placebo (300 mg medium chain triglycerides/daily) or gernaylgeraniol supplementation (300 mg GG/daily). Subjects will be required to fast for 8 hours with no alcohol consumption before their blood draw. Baseline blood samples will be drawn before administering one of two treatments with subsequent blood samples to be drawn in the morning (between 7 am and 8 am) at 8, 10, and 18 weeks. Each participant will take the assigned intervention daily with breakfast for the following 8 weeks. After a 14-day washout period, this process will be repeated for the remaining treatment. Self-reported height and weight will be obtained to calculate body mass index (BMI). Questionnaires on overall health (SF-36) and sexual health [PROMIS Sexual Function and Satisfaction (SexFS) v2.0 Brief Profile (Male/Female)] will be assessed at baseline, 8, 10, and 18 weeks. All laboratory testing will occur at a LabCorp patient service center. The serum samples will be analyzed for Free and Total Testosterone using liquid chromatography with tandem mass spectrometry (LC-MS-MS). LabCorp test code: 070195; Serum Sex Hormone-Binding Globulin (SHBG) will be analyzed using Electrochemiluminescence immunoassay (ECLIA). LabCorp test code: 082016. Coenzyme Q10, Total (CoQ10). LabCorp test code: 120251.

Study Type

Interventional

Enrollment (Actual)

34

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Florida
      • Palm Coast, Florida, United States, 32164
        • Designs for Health, Inc.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  1. Males and females between 40 to 65 years of age.
  2. Individuals with no significant history of inflammatory bowel disease (i.e. ulcerative colitis, Crohn's, Celiac, etc.), ulcers, liver and/or kidney disease or other any acute or chronic dis-ease.
  3. Ability to read and speak English
  4. Subject's agreement to voluntarily participate in the study
  5. Negative pregnancy test confirmed with serum HCG on initial baseline testing and baseline testing at the start of the crossover (at 10 weeks)

Exclusion Criteria:

  1. Males and females under 40 or over 65 years of age
  2. Previous (in the past 60 days) or current hormone replacement therapy
  3. Males and females with free testosterone levels over normal range
  4. History of hysterectomy, oophorectomy, or orchiectomy
  5. Current biotin supplementation >3 mg per day one week prior to the start of the study
  6. Current or history of smoking
  7. CoQ10/Ubiquinol supplementation within the past 2 weeks
  8. Current use of hormone boosting supplements (i.e. fenugreek, shilajit, tongkat ali, ashwagandha) within the past 4 weeks
  9. Current or previous use of medication - NSAIDS, statins, blood thinners, H2 blockers and PPI or blood sugar-lowering agents.
  10. Diabetes
  11. Cancer
  12. Hemophilia
  13. Disorders of heart, kidney, lung or liver function
  14. Infectious diseases
  15. Alcohol or drug abuse (>7 drinks per week for men and women)
  16. Pregnancy, lactation, or individuals planning to become pregnant in the next 6 months
  17. Failure to submit statement of consent
  18. Participant in a clinical trial in the previous 30 days.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Non-Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Placebo
Dietary supplement: Placebo
300 mg medium chain triglycerides
Experimental: Geranylgeraniol 300 mg
Dietary supplement: Geranylgeraniol 300 mg
300 mg of trans-geranylgeraniol (GG)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Serum Total Testosterone (LC/MS-MS)
Time Frame: Baseline, 8 weeks, 10 weeks, and 18 weeks
Can aid in the diagnosis of androgen dysfunction in men and women and is more specific method of measuring testosterone concentrations. Units in ng/ml.
Baseline, 8 weeks, 10 weeks, and 18 weeks
Serum Free Testosterone (Direct)
Time Frame: Baseline, 8 weeks, 10 weeks, and 18 weeks
The concentration of unbound testosterone in serum. The majority of serum total testosterone is associated with sex hormone binding globulin (SHBG) and this fraction is tightly bound and bio-logically unavailable to its target tissues. The remaining bioavailable testosterone is mostly bound to albumin, with only a small fraction circulating in the free form. Free testosterone is the form of testosterone that can diffuse into the tissues and act on receptors and is considered the active fraction. Free testosterone assessment is recommended as a primary or secondary measure of androgen activity in men and women. Units in pg/ml.
Baseline, 8 weeks, 10 weeks, and 18 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Serum Sex Hormone Binding Globulin (SHBG)
Time Frame: Baseline, 8 weeks, 10 weeks, and 18 weeks
The blood transport protein for testosterone and estradiol. SHBG binds reversibly to sexual steroids and is an important indicator of an excessive/chronic androgenic action where androgen levels are normal, but where clinical symptoms would seem to indicate androgen in excess. SHBG is a useful supplementary parameter in the determination of androgen where a high concentration of free androgen (i.e., testosterone) is suspected. Reference ranges in men: 20-49 years: 16.5-55.9 nmol/L; >49 years: 19.3-76.4 nmol/L. Reference ranges in women: 20-49 years: 24.6-122.0 nmol/L; >49 years: 17.3-125.0 nmol/L.
Baseline, 8 weeks, 10 weeks, and 18 weeks
Coenzyme Q10 (CoQ10)
Time Frame: Baseline, 8 weeks, 10 weeks, and 18 weeks
CoQ10 is endogenously synthesized via the mevalonate pathway and some is obtained in the diet from meat products. It is also a powerful lipid-soluble antioxidant protecting cell membranes and lipoproteins. Reference range: 0.37-2.20 µg/mL.
Baseline, 8 weeks, 10 weeks, and 18 weeks
SF-12- Health Survey
Time Frame: Baseline, 8 weeks, 10 weeks, and 18 weeks
The SF-12 (Short Form Health Survey) is an indicator of overall health status across eight scales: physical functioning, role physical, bodily pain, general health, vitality, social functioning, role emotional, and mental health.
Baseline, 8 weeks, 10 weeks, and 18 weeks
PROMIS- Sexual Health and Satisfaction
Time Frame: Baseline, 8 weeks, 10 weeks, and 18 weeks
Sexual health [PROMIS Sexual Function and Satisfaction (SexFS) v2.0 Brief Profile (Male) and (Female)]. The SexFS assesses interest in sexual activity. These are domains relevant to healthy individuals.
Baseline, 8 weeks, 10 weeks, and 18 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Designs for Health

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 30, 2025

Primary Completion (Actual)

September 19, 2025

Study Completion (Actual)

September 19, 2025

Study Registration Dates

First Submitted

December 18, 2024

First Submitted That Met QC Criteria

December 18, 2024

First Posted (Actual)

December 24, 2024

Study Record Updates

Last Update Posted (Actual)

May 1, 2026

Last Update Submitted That Met QC Criteria

April 29, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AR - 30040

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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