PHYTOESTROGENS AND HAIR GROWTH

Research published by Ebling in 1957, demonstrates that estrogens increased the growth rate of cells in the skin, hair and reduced the size and activity of sebaceous glands.  The two main estrogens that effect hair growth are estradiol (E2) and estrone (E1).  Estradiol is a more potent activator of hair growth than estrone but must be synthesised from testosterone.  Phytoestrogens are plant derived estrogenic compounds that influence the production of growth factors that control the anagen (growth) and telogen (resting) phase of the hair follicle

WHAT ARE PHYTOESTROGENS?

Phytoestrogens are a general term for compounds of various structures originating from plant sources that mimic or modulate the action of estrogenic hormones.  The estrogenic potential of certain plants was first reported in the 1940s from an observation of sheep that suffered reproductive disorders because of a diet mostly based on clover.

Female hop-pickers suffered disturbances in their menstrual cycles during the hop harvests.  This phenomenon led to the assumption that hops exerted estrogenic activities.  The active substance 8-PN (8-prenylnaringenin), responsible for the estrogenic effect in hops, was identified in 1999 by Milligan [1].

Phytoestrogens in the body act like weak estrogens and when applied topically will not impact overall hormonal balance in the body.  Estrogens profoundly alter hair growth by binding to estrogen receptors in the hair follicle.  Besides altering estrogen dependant genes, estrogen modify hair follicle metabolism in the hair follicle and the sebaceous gland.

The most well-known phytoestrogens have been shown to modulate the hair growth cycle and clinical trials have shown that soy isoflavones help reduce the severity of alopecia areata.

ESTROGENS MODULATE HAIR GROWTH FACTORS

Hormonal alterations affect hair growth because they increase or decrease growth factors that influence hair follicle survival.  Growth factors directly control how long hair remains in anagen phase (growth phase) and when hair goes into telogen (resting phase) in preparation to be shed.

Induction of anagen phase is dependent on transforming growth factor beta, keratinocyte (keratin cell) growth factor (KGF) and fibroblast growth factor (FGF).  Maintenance of anagen phase is controlled by insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF).

The anagen-to-catagen transition involves crosstalk between keratinocyte growth factor and transforming growth factor-beta. Estrogens and estrogen receptors play an important role in the signalling pathways that regulate hair growth.  Functional crosstalk between estrogens and receptors regulate the action of growth factors that control the hair growth cycle.

HOW DOES PHYTOESTROGEN THERAPY WORK?

Two types of estrogen receptor are distinguishable in the human hair follicle.  Estrogen receptor α is involved in keeping the hair follicle in anagen (growth) phase, while estrogen receptor β is responsible for inducing telogen in preparation for hair to be shed.  In humans estrogen receptor α is the predominant estrogen receptor in hair follicles.

Due to the mixed ability of 8-PN to interact with estrogen receptor α and estrogen receptor β, this compound can exert actions that increase hair follicle growth.  Phytoestrogens can act as an anti- estrogen by temporarily binding to estrogen receptor β, thus inhibiting the telogen inducing activity of human estrogen by blocking binding sites.

This means 8-PN can prevent activation of estrogen receptor β and reduce premature telogen and extend anagen phase.

Compounds binding to an estrogen receptor usually have a preferential affinity to one receptor type. In this regard, most phytoestrogens show a preference for estrogen receptor β, while 8-PN predominantly binds to estrogen receptor α.

Phytoestrogens for hair growth
Phytoestrogens for hair growth

THE FINAL WORD

The interaction of 8-PN with estrogen receptors makes it a powerful compound for the reversal hormone dependent hair loss disorders.  Topically applied phytoestrogens are an effective component of any hair loss regime designed to reduce the severity and reverse the effects of hair loss and support adequate hair regrowth in men and women.

REFERENCES

  1. The action of testosterone on the sebaceous glands and epidermis in castrated and hypophysectomized male rats.
  2. Identification of a potent phytoestrogen in hops (Humulus lupulus L.) and beer. J. Clin. Endocrinol. Metab. 1999;84:2249. doi: 10.1210/jcem.84.6.588
  3. Administration of capsaicin and isoflavone promotes hair growth by increasing insulin-like growth factor-I production in mice and in humans with alopecia. Growth hormone & IGF research. 2007 Oct 1;17(5):408-15.
  4. Estrogens and the hair follicle: Östrogene und der Haarfollikel. JDDG: Journal der Deutschen Dermatologischen Gesellschaft. 2004 Jun;2(6):412-23.
  5. In Vitro Comparison of Estrogenic Activities of Popular Women’s Health Botanicals. Master of Science Thesis, University of Illinois. doi 10 (2015).
  6. The type of dietary fat affects the severity of autoimmune disease in NZB/NZW mice. The American journal of pathology. 1987 Apr;127(1):106.
  7. Oxidative stress and alopecia areata. Journal of Medicine and Life. 2015;8(Spec Issue):43.