An Updated Etiology of Hair Loss and the New Cosmeceutical Paradigm in Therapy: Clearing ‘the Big Eight Strikes’

In this current review, research spanning the last decade (such as transcriptomic studies, phenotypic observations, and confirmed comorbidities) has been synthesized into an updated etiology of hair loss and applied to the new cosmeceutical paradigm of hair rejuvenation. The major etiological components in scalps with hair loss are denoted as the ‘big eight strikes’, which include the following: androgens, prostaglandins, overactive aerobic metabolism of glucose, bacterial or fungal over-colonization, inflammation, fibrosis, metabolism or circulation problems, and malnutrition. The relevance of the ‘big eight’ to nine categories of hair loss is explained. In cases of androgenetic alopecia or female pattern hair loss, both elevated DHT and increased frequency of androgen receptors lead to problems with the metabolism of glucose (sugar), redox imbalance, disruption to the electron transport chain, and PPAR-γ overactivity (the latter is unique to androgenetic alopecia, where the reverse occurs in other types of hair loss). These etiological factors and others from ‘the big eight’ are the focal point of our hypothetical narrative of the attenuative mechanisms of commercial cosmeceutical hair serums. We conclude that cosmeceuticals with the potential to improve all eight strikes (according to published in vitro or clinical data) utilize bioactive peptides and plant compounds that are either flavonoids (isoflavones, procyanidins, flavanols, and flavonols) or sterols/triterpenes. It is noteworthy that many therapeutic interventions are generic to the multiple types of hair loss. Lastly, suggestions are made on how scalp and hair health can be improved by following the cosmeceutical approach.