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How SHBG and Your Genetics Affect Free Testosterone

Testosterone plays a central role in male health. It influences libido, mood, muscle mass, bone strength, and fertility. But total testosterone on a lab report is only part of the story. Sex hormone binding globulin, or SHBG, is a liver-produced protein that binds testosterone in the blood. The amount of SHBG determines how much testosterone is tied up and how much remains free and biologically active.

Variants in the SHBG gene can raise or lower SHBG levels. Higher SHBG generally means less free testosterone even if total testosterone looks normal. Knowing your genotype at rs12150660 can help explain symptoms and guide lifestyle, diet, testing, and supplement choices to support healthy testosterone balance.

How to read this page

  • The accordion below explains what each rs12150660 genotype commonly means for SHBG and free testosterone.
  • After the genetic interpretations you will find clear, practical recommendations for diet, supplements, lifestyle, and tests you can discuss with your healthcare provider.
  • PlexusDx does not provide medical advice. Always consult your healthcare provider before making changes to medications, supplements, or treatment plans.

Genetic interpretations

GG — Two effect alleles (higher SHBG, lower free testosterone)

Having the GG genotype at rs12150660 is associated with higher SHBG levels. Higher SHBG binds more circulating testosterone, which lowers the amount of free, active testosterone available to tissues. This can lead to signs of reduced testosterone activity such as lower libido, decreased energy, reduced muscle mass, changes in mood, and potential impacts to bone density and fertility, even if total testosterone measures in the “normal” lab range.

Practical takeaways:

  • Consider focused lifestyle strategies to maximize free testosterone (see recommendations below).
  • If you have symptoms, discuss with your provider the value of measuring free testosterone or calculated free testosterone in addition to total testosterone.
  • Work with your provider before starting any hormones or prescription therapies.
GT — One effect allele (intermediate SHBG, possible modest reduction in free testosterone)

With the GT genotype you carry one copy of the effect allele. This often corresponds to a moderate increase in SHBG compared to the non-effect genotype. The result can be a mild to moderate reduction in free testosterone. Symptoms may be subtle or may appear under stressors such as weight gain, poor sleep, or high alcohol intake.

Practical takeaways:

  • Early attention to lifestyle factors like sleep, weight, and alcohol can help prevent symptoms from emerging.
  • If symptomatic, ask your provider about testing free testosterone and reviewing medications or exposures that raise SHBG.
TT — Two non-effect alleles (typical SHBG, generally healthier free testosterone availability)

The TT genotype is associated with typical or lower SHBG levels compared to carriers of the G allele. This generally supports greater availability of free, active testosterone for tissues that rely on it. People with TT tend to have a genetic advantage for maintaining free testosterone, though lifestyle and health conditions still matter.

Practical takeaways:

  • Continue healthy lifestyle habits that support testosterone and overall health.
  • Even with favorable genetics, monitor for changes with age, weight gain, or illness that can reduce free testosterone.

Diet and nutrition recommendations

Diet plays an important role in hormone balance. Aim to support liver function, stable blood sugar, and healthy body composition.

  • Prioritize protein: Aim for high-quality protein at each meal to support muscle mass and hormone production. Include lean meats, fish, eggs, dairy, legumes, and nuts.
  • Healthy fats: Include sources of monounsaturated and omega-3 fats such as olive oil, avocados, fatty fish, and walnuts. Dietary fat supports hormone synthesis.
  • Anti-inflammatory choices: Emphasize vegetables, berries, whole grains, and foods rich in antioxidants to reduce chronic inflammation that can disrupt hormone balance.
  • Limit refined carbs and added sugars: Excess sugar and spikes in insulin can negatively affect hormone signaling and fat distribution.
  • Moderate alcohol: Alcohol can raise SHBG and reduce free testosterone. Keep intake low to moderate or avoid if you have symptoms consistent with low free testosterone.
  • Avoid exposure to endocrine-disrupting chemicals: Reduce contact with BPA and phthalates by limiting use of certain plastics, using glass or stainless steel containers, and avoiding microwaving plastic.

Supplement considerations

Supplements may provide support but should be used thoughtfully and under the guidance of your healthcare provider.

  • Zinc: Adequate zinc status is important for testosterone production and reproductive health. Consider testing levels before supplementing long term.
  • Boron: Small studies suggest boron can increase free testosterone and lower SHBG in some men, but dosing and safety should be discussed with your provider.
  • Ashwagandha: An adaptogen that may reduce stress and support healthy testosterone and libido in some men.
  • Shilajit: Traditional mineral-rich resin that has been associated with improved testosterone markers in some studies.
  • Vitamin D: Low vitamin D status is linked to lower testosterone. Consider testing 25(OH)D and supplementing to reach optimal levels if deficient.
  • Do not start or stop prescription hormones or make major supplement changes without medical supervision.

Exercise, sleep and lifestyle

  • Strength training: Regular resistance exercise preserves and builds muscle mass and supports testosterone signaling. Aim for 2 to 4 sessions per week.
  • Moderate aerobic activity: Cardio helps with weight management and cardiovascular health. Combine with strength training for best hormone benefits.
  • Sleep: Prioritize 7 to 8 hours of quality sleep nightly. Poor sleep raises stress hormones and can reduce free testosterone.
  • Weight management: Maintaining a healthy body fat percentage helps keep SHBG and insulin in favorable ranges. Even modest weight loss can improve free testosterone.
  • Stress reduction: Chronic stress raises cortisol which can suppress reproductive hormones. Use relaxation strategies such as breathing exercises, mindfulness, or regular physical activity.

Blood tests and when to see a provider

If you have symptoms that suggest low free testosterone such as persistent low libido, fatigue, loss of muscle mass, mood changes, or fertility concerns, discuss the following with your provider:

  • Total testosterone and free testosterone or calculated free testosterone (free T gives clearer insight when SHBG is altered).
  • SHBG level to understand how much testosterone may be bound and unavailable.
  • LH and FSH to assess pituitary function if there are signs of low testosterone.
  • Vitamin D, zinc, fasting glucose or HbA1c, and lipid profile to check metabolic and micronutrient status.
  • Review medications and exposures that can raise SHBG or lower testosterone.

Important disclaimers

This educational content is provided by PlexusDx to help explain how SHBG genetics can influence free testosterone and practical ways to support hormone health. This is not medical advice. Always consult your healthcare provider before making changes to medicines, supplements, or treatment plans, and before starting a new exercise or nutrition program. Your healthcare provider can interpret genetic findings in the context of your personal health history and recommend appropriate testing or treatments.