Should you get sulphate free shampoo?

Should you get sulphate free shampoo? 

Sulphates are a real buzz word in the shampoo industry at the moment. There are a lot of brands going 'sulphate free' but when speaking to a lot of our customers, understanding of what sulphates are and why they might want to go 'sulphate free' was quite muddled! So in this blog we're going to try and clear up some of the confusion based on the science that is actually out there and answer the following questions:

 

To answer these questions, we first must understand what a surfactant is, why we need to wash our hair, what sulphates are and a little bit about the protective layers of lipids present in our hair.

 All shampoos have cleansers in them known as surfactants, (surface active agent). If you have some dirt in your hair mixed with oil it can be difficult to remove with water alone. You need something to bind with the oil making it easier to rise off. Enter surfactants.

 Surfactants look like tadpoles with a large hydrophilic (water loving) head and a thin hydrophobic (water hating) tail. The tail attracts oil and dirt, when there are enough surfactants in your solution, they group together with the heads pointing out wards and the tails (containing the dirt) at the centre, looking like a spherical ball. This is known as a micelle. The micelles are easily washed away when you rinse your hair so removing the dirt and oil with it.

There is a strong school of through that thinks it is essential to remove the excess dirt and sebum as a build-up of this along with dead skin cells, bacteria and viruses causes blocked pores, itchy skin and dull oily looking hair. Sebum also begins to be chemically altered as soon as it reaches the scalp surface; the longer it sits on the scalp, the greater these modifications. Specifically, modified sebum contains free fatty acids and oxidized lipids, which are known to be irritating to skin (1). Against this school of thought are those who practice the no-poo method - more of that in a later blog.

 

Without surfactants it would be difficult to wash away the dirt and oil from your hair, so most conventional shampoos contain some type of surfactant.

 

There are many different types of surfactants, some stronger than others. One group of surfactants that are well known are called sulphates.

Anything with the word sulphate at the end means that the molecule has been combined in some way through the process of sulfonication, in other words adding a salt of sulphate molecule. Say for example you want to use coconut oil as the base of your cleanser, coconut oil is too oily to work well as a cleanser on its own, however if it is sulphated then it becomes much more soluble. Further combining   this with say sodium or ammonium - again something very soluble , and you have a cleanser that cleans and foams very well in water.

 

Sulphates are everywhere that likes to foam, toothpaste, cleansers, body washes and shampoos as well as some household cleansers such as washing up liquid.

 

Within the sulphate groups there are two well-known types, SLS (sodium lauryl sulphate) and SLeS (sodium laureth sulphate).

Both these sulphates, while being very good cleansers have differing degrees of strength and skin irritation. SLS and SLeS have been shown to be more irritating on the skin than other gentler surfactants. SLS has also been shown to irritate young skin more than old skin. (2)

 

Less well talked about (and gentler) sulphates are alkyl ether sulphates and amide ether sulphates. These sulphates have been shown to be gentler than SLS and SLeS and also some other surfactants out there. The overall formulation of the product is also important, rather than relying on the presence of a single ingredient, the mildness and general safety of a cosmetic product is always highly reliant on the total formulation as well as the clinical and safety testing preformed on the product.

So is gentler always better? Well to answer that its good to have a basic understanding of how surfactants work. In a nutshell (and as described above) surfactants remove oils, dirt and dead skin cells from the hair. They also remove lipids. This is where it gets a bit tricky. 

 

 

Hair lipids can be found both outside the hair shaft derived from sebum and within the hair shaft derived from the hair matrix cells. (3)

Only one layer of lipids called the 18 MEA layer is bonded to the outer cuticle.

 

Lipids have been shown to be essential in protecting the hair against damage and for the maintenance of healthy hair. Removal of lipids decreases tensile strength, shine and fineness of hair while increasing permeability. (3)

Shampoos containing surfactants remove some of these lipids to greater or lesser extent. Some shampoos containing  sulphates can remove too much of the protective lipid layer rendering the hair shaft more vulnerable to penetration from foreign matter and to leaching out  of internal hair colour. It is important to note that the more the sulphate quantity within the formula the more pronounced this effect.

Because of their excellent cleansing properties SLS and SLeS can remove too much of the good lipids from your hair. This is particularly relevant with coloured hair - as the good lipids  help protect the leaching of colour from your hair. (3)

Most hair dyes work by penetrating the cuticle then stripping the cortex of its natural colour. Once this is achieved, they undergo  a process of oxidation which  adds its own colour. This oxidative process makes the coloured hair particles larger so trapping them within the cortex  beneath the cuticle.

However, during the colouring process, in penetrating the cuticle the outer layer of lipids including the 18 MEA layer is damaged. If the chemical process has removed the 18 MEA layer - this is permanent - it won’t recover until new hair is grown in. (4). This means at each wash the cuticle is more permeable than usual allowing colour to leach out.

So even washing with water alone, over time, causes a leaching of the colour. This is accentuated by washing with strong surfactants which include SLS and SLeS - as, without the protective 18 MEA layer you are relying on the protective outer layer of  lipids from sebum and if they are all stripped away your protection is gone. You can substitute this protective layer with an externally applied topical layer i.e. conditioner which is why it is essential to condition coloured hair.

 

So, in summary, our hair is protected by a healthy layer of lipids made both by sebaceous glands, sebum (5 & 6) and hair shaft itself. One of these layers known 18 MEA  is bonded to the outer cuticle layer.

To a greater and lesser extent, hair colouring removes the 18 MEA layer - an effect  which once it has happened is permanent.

Shampooing removes excess sebum (lipids) as well as dirt and other foreign particles.

If you have coloured, dry, damaged or curly hair, if you are a child (2) or you have sensitive skin or a skin condition such as rosacea or eczema and your shampoo contains sulphates formulated at a high level then too much of the protective lipids will be removed and there is a potential for skin irritation. In the case of coloured hair this will accentuate the rate of leaching of the colour. A gentle shampoo containing gentle surfactants would be a safer option.

But it’s fair to say, however gentle your shampoo, you should always condition if you have coloured hair.

 

There have been contradictory findings regarding the safety of the compound, indicating its potential toxicity, and various regulatory bodies, including the Environmental  Protection Agency, National Institute for Occupational Safety and Health, and Environmental Defence Fund having contrasting decisions regarding the regulation of SLS, with some indicating environmental risk and others stating it is less hazardous. An article in Science Direct (7) summarised that ‘exposure to SLS can elicit changes to various organismic processes and environmental equilibrium. Hence further study on SLS in various environmental compartments is recommended to monitor the level of SLS pollution’.

 

There is no scientific evidence supporting some claims that sulphates can cause cancer. These claims appear to be misinterpretations of scientific literature. SLS is not listed as a carcinogen by the International Agency for Research on Cancer (IARC), US national toxicology program, EU and US Environmental Protection Agency.

So as always, the answer is more nuanced than some google searches may suggest. Many people can tolerate a degree of sulphates within their shampoo, especially well formulated shampoos with lower levels of sulphates and the gentler types of sulphates. They are however, known skin irritants and it is wise to consider a sulphate free shampoo if you fall into any of the categories below:

- coloured hair

- dry hair

- damaged hair

- curly hair

- you are a child

- you have sensitive skin

- you have a skin condition such as rosacea or eczema.

 

We are all different and there is no one size fits all.

As always, due to our differences, it is important to choose which shampoo is right for you.

 

All of An’du’s shampoos contain gentle cleansers and are sulphate free. They have additional grapeseed oil to help moisturise the hair shaft and their main cleanser based on is coconut oil. Because of this they are safe to use on coloured hair and will not cause increased leaching of the colour.

 

 

 

 

References

 

1. The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions

Supriya Punyani,a Antonella Tosti,b Maria Hordinsky,c Dawn Yeomans,d and James Schwartzd,*

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8138261/

 

3.Hair Lipid Structure: Effect of Surfactants

by Luisa Coderch *, Cristina Alonso, M. Teresa García, Lourdes Pérez and Meritxell Martí

Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), Jordi Girona, 18-26, 08034 Barcelona, Spain

 

4. https://www.dermatologytimes.com/view/poor-condition-dermatologist-disagrees-products-claiming-replenish-hair-shaft-component

 

5. https://dermnetnz.org/topics/sebum

 

6. Dermatoendocrinol. 2009 Mar-Apr; 1(2): 68–71.

doi: 10.4161/derm.1.2.847 Sebaceous gland lipids

Mauro Picardo, Monica Ottaviani, Emanuela Camera, and Arianna Mastrofrancesco

  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2835893/

 

 

7. Sodium lauryl sulfate and its potential impacts on organisms and the environment: A thematic analysis

Author links open overlay panel

Johannes Reiner G. Asio a 1, Janice S. Garcia a, Charalabos Antonatos b, Janice B. Sevilla-Nastor a, Lorele C. Trinidad c

The photograph for this blog was taken by Jannah from @lovelunalight_photography