Ways to decrease SHBG and increase your Free Testosterone

Sex Hormone Binding Globulin (SHBG) binds to testosterone in the blood. When SHBG is high, less testosterone is “free” (biologically active). Lowering SHBG can increase free testosterone — but only if total testosterone is adequate to begin with.

Below are nutritional supplements that have evidence for helping reduce SHBG or increase free testosterone.

1. Boron (Most Direct Evidence)

• Dose: 3–10 mg daily

  • Evidence: Strongest human evidence for lowering SHBG

• Studies show 6–10 mg/day can:

  • Decrease SHBG

  • Increase free testosterone

  • Lower estradiol

• Effects observed within 1–2 weeks

• Best form: Boron glycinate or citrate
  Caution: Stay under 20 mg/day (upper safety limit)

2. Vitamin D3

• Dose: 2,000–5,000 IU daily (based on blood levels)

  • Low vitamin D correlates with higher SHBG and lower testosterone.

  • Supplementation in deficient men increases total and free testosterone.

  • Optimal blood level: 40–60 ng/mL

  • Tip: Take with magnesium for better utilization.

3. Magnesium

• Dose: 200–400 mg daily (glycinate or malate preferred)

  • Magnesium reduces SHBG binding affinity.

  • Can increase free testosterone without raising total T.

  • Especially effective in physically active men.

4. Zinc

• Dose: 15–30 mg daily (avoid >40 mg long-term)

  • Zinc deficiency increases SHBG.

  • Supplementation raises testosterone in deficient men.

  • Also reduces aromatase (less T → estrogen conversion).

Below are natural supplements that have evidence for helping reduce SHBG or increase free testosterone. IMPORTANT: Before taking natural supplements, it’s first important to consult with your doctor to make sure that there are no interactions with medications you may be taking.

5. Tongkat Ali (Eurycoma longifolia)

• Dose: 200–400 mg standardized extract daily

  • May reduce SHBG

  • Increases free testosterone

  • Reduces cortisol (high cortisol can increase SHBG

  • Evidence is moderate but promising.

6. Ashwagandha

• Dose: 600 mg daily (KSM-66 or Sensoril)

  • Reduces cortisol (high cortisol can increase SHBG)

  • Increases total and free testosterone in stressed men

  • Indirect SHBG effects

7. Nettle Root Extract

• Dose: 300–600 mg daily

  • Contains lignans that may bind to SHBG

  • Potentially reduces SHBG binding to testosterone

  • Evidence is mostly mechanistic and limited in humans

Important: What Raises SHBG (and Should Be Addressed First)

Before supplements, address root causes:

• Low insulin (very low-carb dieting can raise SHBG)

• Calorie restriction

• Overtraining

• Hyperthyroidism

• Liver issues

• Aging

• High estrogen

• Low body fat (<10%)

Sometimes increasing calories and carbohydrates lowers SHBG more effectively than supplements.

Most Effective Stack for Lowering SHBG

If someone wanted a simple evidence-based approach:

• Boron – 6 mg

• Magnesium glycinate – 300 mg

• Zinc – 25 mg

• Vitamin D3 – dose based on labs

When Lowering SHBG Won’t Help

If total testosterone is low, lowering SHBG may not significantly increase free T. In that case, you need to increase total testosterone production first (sleep, strength training, body fat optimization, etc.).