Shampoo

cleans by stripping sebum from the hair. Sebum is an oil secreted by hair follicles that is readily absorbed by the strands of hair, and forms a protective layer. Sebum protects the protein structure of hair from damage, but this protection comes as a cost: it tends to collect dirt, styling products and scalp flakes. Surfactants strip the sebum from the hair shafts and thereby remove the dirt attached to it.

Shampoo is a hair care product used for the removal of oils, dirt, skin particles, environmental pollution and/or other contaminant particles that gradually build up in hair. The goal is to remove the unwanted build-up without stripping out so much as to make hair unmanageable.

While both soaps and shampoos contain surfactants, soap bonds to oils with such affinity that it removes too much if used on hair. Shampoo uses a different class of surfactants balanced to avoid removing too much oil from the hair.

The effectiveness of vitamins, amino acids and pro-vitamins to shampoo is also largely debatable. Vitamins and amino acids are the building blocks of proteins and enzymes within the body. While vitamins may be able to penetrate cells through the skin, amino acids and proteins are too large to enter a cell outside the bloodstream, and they can have no effect on dead tissue.

Proteins are constructed from amino acids following an RNA blueprint inside the cell. A strand of hair is a long protein chain continually being added to at the root. The only way for an amino acid to be of any use is to be intentionally bound to other amino acids in a specific fashion by a living cell. Hair is not alive, and there is no possibility for an amino acid or protein to have any permanent effect on the health of the strand.

The case for vitamins is not as well understood. Some have demonstrated a moderate effectiveness in improving the health of skin, but most likely the benefit is derived from the effect of vitamins on living cells below the epidermis. Extending this benefit to hair, the vitamins and minerals could improve the health of new hair growth, but the benefit to existing hair is unsubstantiated. However, the physical properties of some vitamins, like vitamin E oil or panthenol, would have a temporary cosmetic effect on the hair shaft while not having any bioactivity.

How to Choose the Suitable Shampoo for your Hair