Growth Hormone administration via injection, has among other anabolic anti-aging effects, the remarkable and reliable stimulation of scalp hair growth in areas affected by Androgenetic Alopecia. The mechanism underlying this effect has never been elucidated, perhaps until now. 

      Growth Hormone increases levels of Insulin Growth Factor 1 (IGF-1). In prior studies it has been shown that the oral combination of Soy Isoflavones Extract and Capsaicin, in the form of Cayenne Pepper, stimulated hair growth in 90% of both men and women with both hormone driven and autoimmune hair loss. The author found this effect in rats as well, and also discovered that this particular combination dramatically increased levels of IGF- 1 in the dermal papillae.

A study summation with photos is here:

Substance P

      Another study found that the FDA approved hair loss treatment finasteride, (Propecia, Proscar) also increases IGF-1 in the follicular dermal papillae, in those that have a positive hair growth response to the drug. 

Cutaneous Levels of IGF-1, a Therapeutic Target for MPB

      This recently published study lends credence to the prior studies on hair growth stimulation and cutaneous IGF-1, by conclusively demonstrating that Dihydrotestosterone, (DHT) inhibits hair growth by inhibiting IGF-1 production in dermal papillae. 

Growth Horm IGF Res. 2011 Oct;21(5):260-7. Epub 2011 Aug 11.

Dihydrotestosterone inhibits hair growth in mice by inhibiting insulin-like growth factor-I production in dermal papillae.

Zhao J, Harada N, Okajima K.


We demonstrated that insulin-like growth factor-I (IGF-I) production in dermal papillae was increased and hair growth was promoted after sensory neuron stimulation in mice. Although the androgen metabolite dihydrotestosterone (DHT) inhibits hair growth by negatively modulating growth-regulatory effects of dermal papillae, relationship between androgen metabolism and IGF-I production in dermal papillae is not fully understood. We examined whether DHT inhibits IGF-I production by inhibiting sensory neuron stimulation, thereby preventing hair growth in mice. Effect of DHT on sensory neuron stimulation was examined using cultured dorsal root ganglion (DRG) neurons isolated from mice. DHT inhibits calcitonin gene-related peptide (CGRP) release from cultured DRG neurons. The non-steroidal androgen-receptor antagonist flutamide reversed DHT-induced inhibition of CGRP release. Dermal levels of IGF-I and IGF-I mRNA, and the number of IGF-I-positive fibroblasts around hair follicles were increased at 6h after CGRP administration. DHT administration for 3weeks decreased dermal levels of CGRP, IGF-I, and IGF-I mRNA in mice. Immunohistochemical expression of IGF-I and the number of proliferating cells in hair follicles were decreased and hair re-growth was inhibited in animals administered DHT. Co-administration of flutamide and CGRP reversed these changes induced by DHT administration. These observations suggest that DHT may decrease IGF-I production in dermal papillae by inhibiting sensory neuron stimulation through interaction with the androgen receptor, thereby inhibiting hair growth in mice.

The question then becomes how to increase levels of IGF 1 in the dermal papillae to stimulate hair growth in men and women without having to resort to cost prohibitive growth hormone injections?

      As mentioned finasteride, (Proscar/ Propecia) readily accomplishes this, however the side effect price tag is just too steep for many, including myself. Body fat accumulation, sexual side effects, gynecomastia, (breast enlargement in men) are only part of the problem. Finasteride also has been established to cause depression and anxiety due to its specific effects on the neurosteroid, Pregnenolone. Depression is now listed in the Physician’s Desk Reference as an “official” side effect of finasteride. 

      In this particular study, Flutamide reversed DHT mediated changes in the dermal papillae, however Flutamide is a powerful anti-androgen (much stronger than finasteride), used in advanced Prostate Cancer and Gender re-assignment protocols that is simply too feminizing for any practical male use. Even topical versions of this drug used experimentally in MPB have induced gynecomastia in men. 

      Fortunately, Dr Harada, who co-authored this study, has already found that the simple, health promoting- combination of Soy Isoflavones and Capsaicin significantly increased dermal IGF-1 and hair growth in humans. 

Cayenne, Soy Combo for Hairloss