Cystine is the essential nutrient to promote hair regrowth and protect hair from external attacks. [i]

We can all be affected by unexpected hair loss during our lives. Stress, hormonal changes, or seasonal change may impact the physiology of the hair by reducing its resistance and slowing down its growth.

The good news? Cystine is the key component of keratin, that will nourish the hair directly at the root and reactivate the hair growth cycle."

Why does hair fall?

There are two main types of hair loss:

Persistent hair loss or androgenetic alopecia, which is characterized by baldness, and receding hairline and accounts for 80% of persistent hair loss. It affects primarily men (50% are affected within the age of 50), but also 15-20% of women, including 30-40% of menopausal women. [iii, iv]

Temporary hair loss or effluvium, which is characterized by a sudden and significant increase in the amount of hair lost every day. It can be caused by several factors such as childbirth, menopause, change of season, fatigue extreme, a very strict diet, emotional shock, depression, medication, after surgery. [ii]

During pregnancy, for example, estrogen hormones delay the hair loss phase, while after childbirth, the decrease in hormones causes the growth cycle to stop and the premature fall of hair. Similarly, in menopause, the hormonal changes lead to a reduction in the hair growth phase.

On the other hand, the stress triggers our body to produce aggressive particles called free radicals, these components decrease the growth phase and weaken the hair follicle by generating oxidative stress.

Cystine: the essential nutrient for hair growth

The visible part of the hair, the hair shaft, is made of alpha keratin (fibrous protein), with a high sulfur content due to the amino-acid cystine.[v] Cystine is the key component of keratin, its disulfide bridges ensure the stability and strength of keratin in hair.

Cystine is the “raw material”, the elementary part that is used to form keratin and therefore to build the hair. Some scientific studies demonstrate that Cystine, at high doses, increases: [i]

  • Follicle growth rate
  • Hair fiber diameter

Laboratoires Bailleul: Your Life, our priority

[i] Matheson HB et al. Nutrition and metabolism in isolated human hair follicles. Exp Dermatol 1999; 8 (4) : 319-20.
[ii] AAD – American Academy of Dermatology Association, Do You Have Hair Loss or Hair Shedding? Referring to Cheng AS, Bayliss SJ, “The genetics of hair shaft disorders.” J Am Acad Dermatol 2008;59(1):1-22. Available at:'s%20normal%20to%20shed%20between,this%20condition%20is%20telogen%20effluvium, Last access on June 2022
[iii] Mounsey AL, Reed SW. Am Fam Physician. 2009;80(4):356-362.
[iv] Matard Bet Reygagne P. Thérapeutique Dermatologique. Flammarion Médecine Sciences 2001.
[v] Popescu, C. and Höcker, H., Hair-the most sophisticated biological composite material. ChemSoc Rev, 2007, 36, 1282-1291

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