Proteins absorb onto the surface of hair, forming films which help retain moisture and also absorb additional moisture from the environment, functioning as a humectant. These films also act to smooth and flatten the hair cuticle, making the hair shiny and less prone to snarls. The presence of protein coatings on the outer layer of the hair may also provide some protection from pollutants and thermal or UV damage.

Most proteins are hydrolyzed prior to being added to a formula, a chemical process which makes them much smaller (polypeptides or even single amino acids) and more readily absorbed into the cortex of the hair shaft. This absorption can be quite profound when the cuticle layer of the hair is damaged due to chemical, thermal, and mechanical processes. The amino acids or smaller protein fragments act as patches and fill in gaps to help provide strength, elasticity, and shine to the hair. A very high percentage of the protein is retained even after rinsing and subsequent shampoos. For this reason, protein deep treatments can be very beneficial to severely damaged hair.

However, for many people (especially those whose hair may be in reasonably good condition), an undesirable effect of significant protein absorption and retention can be hair that feels dry and brittle. For this reason, use of a moisturizer or oil is often recommended in conjunction with protein deep conditioning treatments. The moisturizer or oil basically acts as a plasticizer that softens the feel of the hair. Another way to avoid this brittle protein buildup is to use protein-containing products sparingly, especially if your hair is not damaged by excessive use of permanent color, perming or relaxing, or heat-styling. I have personally found that periodic use of a good clarifying shampoo can reverse any protein buildup I may experience, and helps me enjoy the positive effects of various protein-containing products in my regimen.

Gentle surfactants in shampoos

  • Sodium cocoyl sarcosinate 
  • Sodium lauryl sulfoacetate 
  • Sodium myreth sulfate
  • Sodium Xylenesulfonate
  • Sodium methyl cocoyl taurate
  • Disodium laureth sulfosuccinate 
  • Cocamidopropyl betaine
  • Coco betaine
  • Cocoamphoacetate
  • Cocoamphodipropionate
  • Disodium cocoamphodiacetate
  • Disodium cocoamphodipropionate
  • Lauroamphoacetate
  • Sodium cocoyl isethionate
  • Decyl glucoside
  • Sorbitol

Q: How can I tell if a shampoo is gentle?

A: The first step in selecting a gentle shampoo is to avoid those containing sodium or ammonium lauryl or laureth sulfate. While it is possible for a formulator to add co-surfactants such as cocamidopropyl betaine or fatty alcohols to the product, which can diminish the harsh detergency effects of those sulfates, there are currently many choices available without them at all. Many “natural” product lines will disguise these sulfates by calling them sodium “coco” sulfate, because the surfactant is in fact derived from coconut fatty acids, but it is still a potentially moisture-stripping surfactant.

When reading labels, look for surfactants on the table we have included. Many of these are from botanical sources, and have been found to be gentle for skin and hair. Often times a combination of two or more surfactants can be even more kind to your tresses. The inclusion of proteins and amino acids, as well as moisturizers such as fatty alcohols, polyquaternium conditioners, silicones (if you shampoo regularly, buildup of these should not be a problem), natural oils, and cationic surfactants will also ensure a gentle cleansing experience.