What is the detergent in soap nuts and how does it work?

What is the soap in Soap Nuts? Soap Bubble Image

Here at PureRescue we believe that plant-based shampoos are better for your hair because they avoid some of the nasty chemicals found in cheap alternatives. They also clean just as well, if not better, than their commercial counterparts. The reason these plant-based shampoos can outclass products made by big chemical companies is because of one or two incredible plants that have soap-like properties. The most prominent and widely-used of them all is appropriately named the soap nut.

The soap nut has enriched countless generations through its ability to clean clothes, bodies and hair. But what is it about this nut that makes it such a good cleanser, if at all?

The science

First of all, we have a little confession to make: The soap nut isn’t actually a nut, it’s a berry. To be fair, this is not a naming scandal, it just that when the small black berry, approximately one inch (2-2.5 cm) in diameter, hardens it ends up looking a lot like a nut. The berry, which grows on the sapindus mukorossi tree in the Himalayas, is deseeded and dried before being used. It contains a natural soap called saponin which functions like a surfactant — i.e. the chemical that binds both with oil and water. Like all surfactants, saponin reduces the surface tension of water, making it easier to get into the fibres your hair to dislodge dirt. When this process is combined with the vigorous movement of your hand, the grime can be rinsed away.

In contrast to commercial shampoos, products containing soap nut do not foam. This can be a little confusing for some consumers because modern marketing has created a strong link in our minds between froth and cleanliness. This is simply not true however — low-foam shampoos have been shown to get rid of grime and grease as well as foamy competitors.

The sustainability

First of all the soap nuts are wild-harvested. They are picked from trees without the use of chemicals, fertilizers and pesticides. That is the fortuitous consequence of the fact that most insects don’t like the taste of saponin. Soap nuts also require very little processing and packaging which means they score really well when it comes to sustainability.

This is no small accomplishment. A carbon footprint study done by Boots in 2008 found that the “raw material extraction” phase was the second biggest contributor to greenhouse gas emissions in the shampoo production process. It contributed approximately 85g of CO2 per 23,5g bottle of shampoo. Because the soap nut eliminates many of the production steps, it allows the environment to breathe just that little bit easier.


Given that the soap nut isn’t actually a nut, even consumers with nut allergies can use it without any apprehension. Soap nuts are naturally hypoallergenic, odorless and particularly gentle on your hair. They are so soft in fact that when soap nuts are used as detergents in washing powders, there is no need for fabric softeners.

A word on aloe vera

Besides the soap nut, aloe vera is also a common addition to plant-based shampoos that deserves a mention here as well. Like its berry counterpart, aloe has a multitude of impressive cleaning properties. These arise primarily from the fact that aloe has a similar chemical composition to keratin — the protein that hair is made of. This means that it is great at rebuilding hair fibres and that it can penetrate the entire length of the hair shaft to repair it.

Aloe also contains 20 amino acids which form the building blocks of the hair and cells in the scalp. Add to that the conditioning properties inherent in aloe and you have an all-round nourishing experience that leaves your hair with a healthy glow.

Photo: Photo by Markus Spiske on Unsplash

Can Soap Be Made From Plants?

Plant Based Shampoos - SLS Free, Paraben Free

At least 75 percent of all new drugs introduced to the public in the last few decades were derived from plants. Specifically, plants have given us medications like morphine, aspirin, and ephedrine — in other words, they’re the reason why most people make it through Monday mornings. Plants also play an indispensable role in the energy industry, already accounting for between 14-18 percent of global renewable energy in the form of biofuel. Oh, and who can forget their irreplaceable service in inhaling the toxic gases we continue to emit into the atmosphere?

You get the point. Plants are and always have served us humans incredibly well. But did you know that their natural Midas touch extends to hair care as well? Below are two of the most beneficial of these plant ingredients.

Aloe, can you hear me?

The aloe plant is a fleshy shrub found in arid regions of the world. It’s packed with proteolytic enzymes which actually help repair the cells on the top of your head.

It can do this because it is made up of many of the components found in keratin (hair). These include: amino acids, oxygen, carbon, hydrogen, nitrogen and sulphur. That means that aloe nourishes hair with its own ingredients.

Aloe also acts against itching, dandruff and all sorts of other embarrassing hair conditions that would cause you to not be invited on a second date. A 1998 study found that the plant did this by reducing scalp inflammation that leads to the white flakes known among scientists as seborrheic dermatitis — this process is further aided by the fatty acids that abound in aloe vera.

Effective cleaning power is another of aloe’s benefits. Unlike some harsher chemicals, it doesn’t damage your hair follicles as it strips oil from the strands. What’s more, it contains vitamins A,C and E. Is it a coincidence that that spells ace, which is the highest card in the deck? I think not.

Going soap nuts

With the exception of a lawmaker and judge whose name is literally “Lord Judge”, there is nothing that has been more appropriately named than the soap nut… because, you know, it cleans, like soap. Used in India longer than most nation states have existed, the soap nut is a cheap, eco-friendly agent that simply does a great job of removing dirt.

When combined with water it forms mild suds that resemble soap, they’re responsible for the cleansing action. Also, beyond being anti-bacterial and anti-fungal, the nut bestow a healthy shine on your hair as a bonus.

Notably, the benefits of the soap nut are not restricted to hair. The pebble-like nuts have natural conditional properties that make them function as a moisturizer too. Many users also enjoy the essential oils contained in them which get rid of pimples and help to even out one’s skin tone.

That’s not it though. One study found that soap nuts are effective in treating the nasty symptoms associated with eczema and other skin conditions.

Bottom line

Unlike the opaque cosmetics industry, nature had nothing but pure intentions when producing these two substances. Both aloe vera and the soap nut have been used safely for many generations. There’s every reason to think they’ll work for you too.