Hair Growth-Promoting Effects of Lavender Oil in C57BL/6 Mice

Hair plays important roles in the body, such as protecting the skin from excess heat and providing various communicative expressions during sudden shocks. Besides, hair acts as a sensory reception for touch feelings that activates the nervous system. In addition, previous studies explain that many people, especially women, regard long hair as an ingredient for beauty. However, there are significant causes of hair loss among individuals due to old age and adverse implications of chronic diseases and medical procedures such as chemotherapy. Although there are several remedies for hair growth, Giray suggests that the lavender oil obtained from plants can boost hair growth. (1) In this article, “Hair Growth-Promoting Effects of Lavender Oil in C57BL/6 Mice,” Lee et al. investigated the impact of Lavender oil on hair growth. (2) While the study produced significant results demonstrating the efficacy in hair growth, the study findings cannot be entirely relied on due to several limitations, including sample size and the generalizability of the results.

Lee et al. included 90 mice purchased from Dae Han Biolink Co (Korea). The animals were purchased a week before the beginning of the experiment to allow them to adapt to the laboratory environment. After the one week, the researchers shaved the backs of each mouse a day before the beginning of the experiment and then divided the female C57BL/6 mice into five groups of 18 mice each; normal group receiving saline treatment, vehicle control group receiving jojoba oil treatment, positive control group under MXD treatment, the first experimental group receiving 3% lavender oil treatment and finally the second experimental group receiving 5% lavender oil treatment. Besides, they took photographs of the mice’s backs to obtain the skin color and the periodic growth of hair alongside the micropipettes, recorded once a day, five times a week, for five weeks. Next, six mice were sacrificed in the first, third and fourth week for skinning with diethyl ether to extract skin tissue samples that were fixed in 10% buffered formalin for 24 hours for further examination. The following findings were obtained; the PC, E1 and E2 groups had increased HF number. After four weeks, the mice in the E1 and E2 groups had a higher hair growth rate than those in the normal group. On the other hand, the dermal thickness, HF number and depth were deepest in the normal group, and there were no significant thymus and hair weight differences across the groups. Lee et al. further obtained that the hair cycle is closely related to HF, so when the growth stage begins, the epidermal layer become thick, and the next stage begins where the epidermal layer becomes thicker, and MCs are distributed around HF.

During the experimentation period, notable shortcomings were evident relating to a small sample and the generalization of findings. To begin with, the researchers used a sample size of 6 mice, which is relatively small, provided the study’s general nature. For the accuracy of results, a researcher ought to use an adequate sample size in the study. Inadequate sample size, characterized by too small or excessive sample sizes, interferes with the overall findings. A small sample size provides a significant probability of study errors, while too much sample may exemplify the study’s conclusions. As outlined by Kim and Seo, the sample size is significant in proving the research hypothesis and effectively reduces study costs. (3) Although lee et al. achieved the aim of the study by producing the intended result, the findings are unreliable due to the small sample size used. While there may be arguments that sample size and generalizability do not affect the overall findings, the sample provided a higher probability of unnoticed errors. Thus, it cannot be concluded that the results are reliable. Secondly, the researchers made it challenging to generalize the results since they used female subjects and did not include male subjects. According to Teresa et al., female and male mice respond differently to doses due to varying immune systems. (4) Although Lee et al. outlined convincing results, the researchers’ exclusion of male mice demonstrated ignorance of these differences, which could have provided better results. Also, the inclusion of male subjects could have identified the possibility of side effects and the duration of the hair to grow. As such, the findings are unreliable to generalize the Lavender oil effect for all. According to Hallberg, the generalization of results is a significant factor to be considered in research. (5) As such, the presence of possible errors and inaccurate measures limited the generalization of findings.

In conclusion, the research focused on a significant subject on the impact of Lavender oil on hair growth. The study produced substantial results, which established that lavender oil could significantly promote hair growth. Nevertheless, the findings were limited by the small sample size and unreliable generalization of results. The number of female C57BL/6 mice enrolled in this study was relatively small, limiting the evaluation of all possible effects of lavender oil on hair growth. Besides, the generalization of findings faced significant hindrance since the effect of lavender oil in the female C57BL/6 mice may vary from the actual reaction in human hair. As such, further studies are needed to investigate the efficiency of lavender oil using human samples. In addition, more studies should evaluate the short and long term adverse effects of lavender oil to prevent future hair damage.

References

1. Giray FH. An analysis of world lavender oil markets and lessons for Turkey. [Internet]. Journal of Essential Oil Bearing Plants. 2018 Nov 2. [Cited 2021 Oct 30]. Available at: https://www.tandfonline.com/doi/abs/10.1080/0972060X.2019.1574612
2. Lee BH, Lee JS, Kim YC. Hair growth-promoting effects of lavender oil in C57BL/6 mice. [Internet].Toxicological research. 2016 Apr. [Cited 2021 Oct 30]. Available at: https://link.springer.com/article/10.5487/TR.2016.32.2.103
3. Hallberg L. Quality criteria and generalization of results from qualitative studies. [Internet]. International journal of qualitative studies on health and well-being. 2013 [Cited 2021 Oct 30]. Available at: https://search.proquest.com/openview/13a9be084dac4fc2cce502e0c9883bbc/1?pq-origsite=gscholar&cbl=2030016
4. Kim J, Seo BS. How to calculate sample size and why. [Internet]. Clinics in orthopaedic surgery. 2013 Sep 1. [Cited 2021 Oct 30]. Available at: https://synapse.koreamed.org/articles/1050195
5. Terres G, Morrison SL, Habicht GS. A quantitative difference in the immune response between male and female mice. [Internet]. Proceedings of the Society for Experimental Biology and Medicine. 1968 Mar. [Cited 2021 Oct 30]. Available at: https://journals.sagepub.com/doi/abs/10.3181/00379727-127-32768