DHT (dihydrotestosterone) is the hormone directly responsible for androgenetic alopecia in men. Understanding the biological mechanism behind DHT-driven hair loss explains why certain foods and supplements can slow it, and why they have limits. This guide covers the science step by step.
What Is DHT and Why Does It Cause Hair Loss?
Testosterone, the primary male sex hormone, circulates through your bloodstream. An enzyme called 5-alpha reductase converts a portion of that testosterone into DHT. DHT is 2.5 to 10 times more potent than testosterone at binding to androgen receptors.
In men with androgenetic alopecia, the hair follicles on the top and front of the scalp have androgen receptors that are genetically sensitive to DHT. When DHT binds to these receptors, it triggers a process called follicle miniaturization.
The Miniaturization Process
Follicle miniaturization happens in stages:
- DHT binds to the androgen receptor on a genetically susceptible follicle
- The growth (anagen) phase shortens from its normal 2-6 years to progressively shorter cycles
- The follicle shrinks with each cycle, producing thinner, shorter, less pigmented hairs
- Terminal hairs become vellus hairs (fine, nearly invisible peach fuzz)
- Eventually the follicle stops producing visible hair entirely
This process does not happen overnight. A single follicle can take 5 to 15 years to go from a healthy terminal hair to a dormant state. That gradual timeline is why early intervention with DHT blockers is effective: you are slowing a years-long process, not trying to reverse an overnight event.
How 5-Alpha Reductase Inhibitors Work
Every DHT blocker, natural or pharmaceutical, targets the same enzyme: 5-alpha reductase. This enzyme exists in two forms:
| Type | Location | Role in Hair Loss |
|---|---|---|
| Type I | Skin, liver, sebaceous glands | Minor contributor |
| Type II | Hair follicles, prostate | Primary driver of scalp DHT |
Finasteride (prescription) blocks primarily Type II 5-alpha reductase, reducing scalp DHT levels by 60-70%. It halts further hair loss in 80-90% of men and produces visible regrowth in roughly 65%. Side effects occur in 2-4% of users.
Dutasteride (prescription, off-label for hair) blocks both Type I and Type II, reducing DHT by up to 90%. It is more effective than finasteride but carries a higher side effect profile.
Natural DHT blockers target the same enzyme but with less potency. Their advantage is a milder side effect profile, which makes them attractive to men at early Norwood stages who want to slow progression without prescription medication.
How Natural DHT Blockers Target 5-Alpha Reductase
Saw Palmetto
Saw palmetto extract contains fatty acids and phytosterols that inhibit both Type I and Type II 5-alpha reductase. A 2012 study measured a roughly 32% reduction in DHT levels among men taking 320 mg daily.
The mechanism is competitive inhibition: saw palmetto compounds compete with testosterone for binding sites on the 5-alpha reductase enzyme, reducing the amount of testosterone that gets converted to DHT.
EGCG (Green Tea Extract)
Epigallocatechin gallate (EGCG) inhibits 5-alpha reductase through a different pathway. Laboratory studies show it directly binds to the enzyme and reduces its catalytic activity. EGCG also has anti-inflammatory properties that may reduce the chronic inflammation around miniaturizing follicles.
The limitation: most human studies on EGCG and hair loss are small. The mechanism is well-understood in vitro, but the clinical dosing required for meaningful scalp DHT reduction in humans is still being refined.
Pumpkin Seed Oil
Pumpkin seed oil contains delta-7-stearine, a compound that competes with DHT for binding at androgen receptors on follicles. Rather than reducing DHT production (like saw palmetto), pumpkin seed oil works downstream by blocking DHT from attaching to the follicle.
A 2014 randomized trial showed 400 mg daily increased hair count by 40% over 24 weeks. The dual mechanism (partial 5-alpha reductase inhibition plus receptor-level competition) may explain why it performs well in studies despite being a single compound.
Zinc
Zinc plays a regulatory role in 5-alpha reductase activity. When zinc levels are adequate, the enzyme functions normally. When zinc is deficient, 5-alpha reductase activity can increase, accelerating DHT conversion.
Supplementing zinc only helps if you are deficient. Men with adequate zinc levels will not see additional DHT reduction from supplementation.
Why Natural Blockers Have Limits
The fundamental limitation of natural DHT blockers is potency. Here is a direct comparison:
| Compound | DHT Reduction | Mechanism |
|---|---|---|
| Finasteride (Rx) | 60-70% | Type II 5AR inhibitor |
| Dutasteride (Rx) | Up to 90% | Type I + II 5AR inhibitor |
| Saw palmetto | ~32% | Type I + II 5AR inhibitor (weak) |
| Pumpkin seed oil | Unknown (partial) | 5AR inhibitor + receptor blocker |
| EGCG | Unknown (partial) | 5AR inhibitor + anti-inflammatory |
At Norwood 2 (800-1,500 grafts if surgical), a 32% DHT reduction may be enough to slow miniaturization for years. At Norwood 4+ (2,500-3,500 grafts), where miniaturization is aggressive and widespread, a 32% reduction is unlikely to keep pace with the rate of loss.
Only 40% of men with pattern baldness are eligible for medication monotherapy. Your Norwood stage determines whether natural DHT blockers are sufficient or need to be combined with stronger interventions.
Putting the Mechanism Into Practice
Understanding the mechanism helps you make smarter choices:
- Stack supplements that work through different pathways (saw palmetto for enzyme inhibition + pumpkin seed oil for receptor blocking) rather than doubling up on the same mechanism
- Do not expect natural blockers to reverse advanced loss. They slow a process; they do not undo years of miniaturization
- Use your Norwood stage as the decision filter. Early stages respond better to mild interventions
Identify your current stage with the free AI assessment at myhairline.ai/analyze, then match your treatment intensity to your level of loss. For a broader overview, read our complete DHT-blocking guide.
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. The biological mechanisms described here are based on published research, but individual responses to supplements vary. Consult a qualified healthcare provider before starting any DHT-blocking protocol.