Caffeine stimulates hair follicle growth and counteracts the negative effects of testosterone

In this study at the Friedrich Schiller University Jena, the effectiveness of caffeine on hair follicles in men with androgenetic alopecia was investigated. The examinations in the hair organ culture model demonstrate that caffeine stimulates hair growth, increases the lifespan of hair follicles, and counteracts the negative effects of testosterone that lead to hair loss.

These results support the use of caffeine as a long-term treatment option against hereditary hair loss.

Hereditary hormonal hair loss (androgenetic alopecia) in men is still a problem that remains unsatisfactorily resolved for many affected individuals. The currently available cosmetic and pharmaceutical products exhibit varying efficacies and side effect profiles.

Since the genetic predisposition to hereditary hormonal hair loss cannot be corrected, effective substances must prevent the impact of the genetic predisposition on the hair root. Thus, the treatment of androgenetic hair loss has a long-term perspective, where the safety and tolerability of the products used must be considered.

Against this background, substances that have few side effects and exert their effect independently of hormonal mechanisms can be a promising alternative.

Since testosterone is a significant factor in the development of androgenetic alopecia, the situation of testosterone's effect on hair was simulated in the so-called hair organ culture model (HOKM).

For the investigations, hairs were obtained from human scalp tissue samples and cultured under laboratory conditions for 6 to 10 days. By selecting young men with early-stage hereditary hormonal hair loss for sample and hair root extraction, the transferability of the results from the lab culture was oriented as closely as possible to the real patient situation. Approximately 20 to 30 hair follicles were extracted from the skin tissue samples. In total, about 600 hair follicles were available for the study.

It was shown that the growth of hair roots under the influence of testosterone was significantly less pronounced than in the control without testosterone (see Diagram 1) and the hair root lost its activity earlier than normal.

This finding correlates with the knowledge that testosterone or its metabolite transfers the hair root into a premature resting phase (telogen). The degree of growth inhibition in the study ranged between 17 and 40 % compared to the control value with pure nutrient medium.

In the search for new active principles against androgenetic alopecia, results on the effectiveness of caffeine against the undesirable effects of testosterone in the skin were surprising. The findings showed that in addition to the generally assumed promotion of blood circulation, there must be other previously undiscovered properties of caffeine. Therefore, caffeine was also investigated on hair follicles from men with early-stage hereditary hormonal hair loss.

It was shown that caffeine could achieve a significant increase in growth in the hair root, which in some cases was as high as +46 %. The promotion of blood circulation by caffeine does not play a role in the model, as the hair organ culture model operates without vascular connection, indicating that caffeine must have a direct influence on the metabolism of the hair root.

Another indication that caffeine specifically improves the vitality of the hair root was provided by measuring the total culture time of the hair follicles in the HOKM. In the presence of caffeine, the lifespan of the hairs in culture increased by 37 % compared to the control.

After the growth-suppressing effect of testosterone and the growth stimulation by caffeine were demonstrated in individual experiments with the respective substances, a mixed model containing both testosterone and caffeine, and testosterone in combination, was finally used to investigate whether caffeine could counteract the suppression by testosterone.

As a result, it was shown that caffeine was able to counteract the suppression of hair growth induced by testosterone and even stimulate hair growth beyond the norm. Thus, it was confirmed in the HOKM that caffeine can neutralise the undesirable effects of testosterone, which are responsible for the deterioration of hair follicles in androgenetic alopecia, and establish a balanced state in the hair root that corresponds to that in untreated control hair follicles.

It should be noted that caffeine could represent a potent growth stimulant for long-term treatment as a preventive measure in androgenetic alopecia, because under laboratory conditions that mimic hair growth in men with hereditary hormonal hair loss, a significant effectiveness on follicle growth is demonstrated compared to controls.