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.

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.

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.