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Rob (PHH)

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Retinol is a derivative of vitamin A sometimes referred to as vitamin A1 and is thought of as the “active” form of vitamin A. Retinol is found in animal based foods only. In recent years, retinol has been an addition to skin and hair products that claim to support hair health and growth.

Key insights:

  • The in vitro (in cells) evidence suggests that retinol treatment could increase the proliferation (cell division) of certain cells related to the hair follicle – like keratinocytes – but not in others – like dermal papilla cells (specialized cells involved in hair follicle growth and cycling) unless it’s paired with minoxidil. In this case, it significantly enhances the cell growth of both keratinocytes and dermal papilla cells.
  • The in vivo (in mice) evidence suggests that the efficacy of retinol treatment supplemented through diet is highly variable (in some cases assisting with hair growth and in some cases contributing to hair loss) and is dependent on dose, the type of hair loss, time of diet change and type of mouse strain (some mice are bred to have genetic mutations that make them lose their hair).
  • The clinical evidence suggests that vitamin A derivatives may not affect hair growth parameters in the short term, and when combined with minoxidil do not improve hair growth outcomes more than just minoxidil alone. However, a study in 1989 found that a combination of high dose retinol and l-cysteine decreased the number of resting (telogen) hair follicles, while increasing the number of growing (anagen) hairs for patients with diffuse alopecia. Unfortunately, because the researchers didn’t include groups for individual treatment, it’s not possible to know if the effects are due to retinol or to l-cysteine.
  • Our experience tracking members: retinol by itself is not enough to improve hair loss outcomes.
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