TOKYO -- July 15, 2025 -- Why do we have hair? How does it grow? And how can we keep it healthy? Aderans Co., Ltd., a global leader in hair, beauty, health and medical wellness, asked a certified Hair Adviser® to share expert insights into the structure, functions, and care of hair -- answering everyday questions and offering tips for healthy growth.
How Hair Works
Hair is made mostly of protein and consists of three layers:
● Cortex: The thick, central layer that holds moisture and gives hair strength.
● Cuticle: The outer protective layer made of overlapping hard protein scales that repel water and bind with oils.
● Medulla: A hollow core, often absent in fine hair, thought to insulate the scalp from temperature changes.
Hair begins forming in the fourth month of fetal development, with the number of follicles determined at birth -- about 100,000 to 120,000 for the average Japanese person. Each follicle produces two to three hairs, which grow for 2-6 years, fall out, and regrow in a repeating cycle. About 80-100 hairs are shed naturally each day. Hair grows roughly 1 cm per month, with the visible shaft made up of "dead" keratinized cells. Once damaged, hair cannot repair itself naturally.
The Purposes of Hair
Hair serves several important roles:
● Temperature regulation: Insulates the scalp from heat and cold.
● Impact protection: Cushions the head from pressure and blows.
● UV protection: Melanin in dark hair absorbs ultraviolet rays, helping shield the scalp -- though both hair and scalp still require UV protection.
Hair Q&A
● Can you tell someone's nutritional status from their hair?
Not completely, but hair can reveal mineral, lipid, and hormone levels, and can be used for DNA and drug testing.
● Does hair get sunburned?
Yes -- UV rays can discolor hair and shorten the life of hair color treatments.
● How long can hair grow?
Growth phases last 2-6 years, allowing hair to reach up to about 72 cm, depending on genetics and health.
● Why does hair grow faster for some people?
Blood circulation, nutrition, sleep quality, stress, seasonal changes, and age all affect growth speed.
Expert Tips
● Protect from UV: Use hair and scalp sunscreens like BeauStage UV Protect Premium Beautiful & Sports to prevent dryness, breakage, and loss of shine.
● Encourage growth: Medicated lotions like HairRepro Medicated Hair Growth Tonic Scalp Grow EX F contain active ingredients to promote growth and prevent hair loss.
About the Expert
Keigo Sugimoto, certified Hair Adviser® (JHSA), researches hair structure and function at Aderans. His work using proteome analysis*1 has identified proteins linked to male and female pattern hair loss, with findings presented at major domestic and international conferences*2,*3.
*1 Analyzing the structure and functions of all proteins in a biological sample (e.g., hair)
*2 The 121st Annual Meeting of the Japanese Dermatological Association
*3 The 12th World Congress for Hair Research (WCHR 2022)
Aderans News -- Summer Campaign
The Aderans Official Online Store is running a Summer Campaign through July 31, offering up to 10% off selected scalp care products, including AD&F Ice Shampoo Sparkling Foam and AD&F Ice Shampoo.
https://www.aderans-shop.jp/shop/r/r25summer/ (Japanese only)
Media Contact:
Aderans Co., Ltd.
Group CSR and Corporate Communications Office
TEL: +81-3-6895-9615
e-mail: pr@aderans.com
Aderans website: https://www.aderans.co.jp/corporate/english/