Last updated on May 28th, 2024
We all want natural, affordable alternatives to everyday products, and it creates a bias within ourselves to want to believe they work. One such product is soap nuts, also known as soap berries or soapberries, a natural soap alternative used for centuries. But are soap nuts truly an effective replacement for traditional washing detergents? As much as we’d like it to be a yes, the answer, unfortunately, is mostly no. However, there is a silver lining that reveals a free and even more sustainable way to wash our clothes – using water only. Let’s dive in!
What Are Soap Nuts?
Soap nuts, also known as soapberries, are the fruit of the Sapindus mukorossi tree, commonly found in India and Nepal. The fruit contains saponin, a natural surfactant that has been used for centuries as a cleaning agent. When soaked in water, soap nuts release saponin, creating a soapy solution that can clean clothes. Soap nuts were a valuable resource in regions where they grew naturally. They were used not only for laundry but also for cleaning jewelry and even as a natural remedy for certain skin conditions.
- Sapindus mukorossi, often referred to as the Himalayan soapberry, is found extensively in the foothills of the Himalayas, ranging from Nepal to northern India and into parts of China. This species is particularly valued for its high saponin content, making its nuts ideal for use as a natural detergent.
- Sapindus trifoliatus, known as the South Indian soapberry, is native to warmer southern parts of India. It thrives in coastal areas and is also used for its cleaning properties, though its nuts are generally smaller and slightly less saponin-rich compared to those of Sapindus mukorossi.
Traditional Use
Traditionally, soap nuts were used to wash clothes. Here’s how it was typically done:
- Collecting Soap Nuts: Fresh soap nuts were harvested.
- Preparation: The soap nuts were de-seeded and sometimes crushed to enhance saponin release.
- Soaking: The soap nuts were soaked in water to release the saponin, creating a soapy solution. Fresh, high-quality soap nuts require about 10-15 minutes of soaking, but those stored for a longer time or of lower quality might need half an hour or more.
- Washing: Clothes were scrubbed directly in this soapy water, often in rivers or streams, using hands or wooden paddles.
- Rinsing: The clothes were then thoroughly rinsed in clean water to remove the soap solution.
Modern Research on Soap Nuts
Recent studies testing the cleaning power of soap nuts have been less than encouraging. It seems that the effectiveness of soap nuts in these traditional contexts does not translate to the expectations and demands of modern laundry. Every scientific study we found on the topic indicated that soap nuts performed the same or worse than water.
- A 2013 study in the journal Tenside Surfactants Detergents found that soap nuts performed no better than water alone, noting that using half the amount of regular detergent yielded a washing result almost as good as using the recommended amount.
- A 2012 study in Household and Personal Care Today found that soap nuts performed no better than water alone in the washing machine.
- Tests by the consumer advocacy group Choice found that soap nuts are less effective than plain water. Worse than using water alone. Yikes.
Tradition VS Science
On the one hand, soap nuts have been used as a traditional laundry staple; on the other, the science says no. Here’s what we think is happening, and it’s all down to context. If you are handwashing your clothes in the Himalayan foothills by a river with fresh soap nuts, they’re likely to help with washing. However, if you’re throwing soap nuts into a muslin bag and pressing go on your washer, it’s not going to work well for a few reasons.
Firstly, as we touched on earlier, soap nuts need time to soak to release their saponin. If you haven’t picked them fresh on your way to the river to do your washing, it’s probably a good guess that your soap nuts, which have come halfway across the world via a container ship are not fresh. Their quality will be degraded. You need to soak them for at least 30 minutes to give them their best chance. Many washing machines do have a soak option you could use for this purpose. Next—the hotter the water, the better—up to 90 degrees Celsius. More saponin is released in hotter water. However, using hot water contradicts the environmental benefits supposed by using soap nuts, unless one has access to environmentally friendly heating methods like solar or heatpump hot water systems.
If you’re not doing this vital preparation and just want to conveniently throw the soap nuts into your washer and press go on a short cold wash, soap nuts might give you a worse result than if you used water alone. Saponin can make water a less effective cleaner in two ways:
- Surfactant Interference: Saponins act as surfactants, but if they don’t fully dissolve or disperse, they can create a barrier that prevents water from effectively penetrating and cleaning fabrics.
- Residue Build-Up: Incomplete dissolution of saponins might leave a sticky residue on fabrics, which could attract dirt and hinder the cleaning process.
Simply throwing soap nuts in a muslin bag and popping it in the washer is unlikely to get a result better than just washing with water, and may even yield a worse result, as Choice demonstrated in their results. Usually, this is how soap nuts are marketed as well—a convenient and easy alternative to laundry detergent. This is why in scientific studies, that appears to be what has taken place—the soap nuts are popped in a muslin bag and tossed in the washer. Complaints from the soap nut industry about unfair testing conditions are valid—but the industry has also reaped what it has sowed. You can’t on the one hand provide a set of instructions to make soap nuts appear as convenient and easy to use as laundry detergent, and then cry foul when studies following those instructions yield poor results. Further studies are needed to determine the efficacy of soap nuts when prepared correctly, but even so, their performance is unlikely to approach that of modern detergents—and at best—be a slight improvement when compared to water only.
Environmental Impact
The relatively poor washing performance of soap nuts is further complicated by their actual environmental impact. Soap nuts are biodegradable, chemical-free, and renewable, making them an appealing option for those seeking environmentally friendly alternatives. However, these benefits are significantly undermined by the fact that they are imported from regions like India and Nepal, involving considerable product miles and high embodied energy.
Moreover, the rising demand for soap nuts in Western markets can adversely affect the local economies and ecosystems in the regions where they are harvested. Often, this leads locals to switch to modern detergents, now cheaper than soap nuts as a result of the increased demand. Consequently, the use of soap nuts in the West has a high risk of shifting the environmental burden of detergent use to areas likely lacking support from robust sanitation and sewage systems, overall exacerbating the impact of detergent use.
If all this wasn’t enough, soap nuts pose a risk as an environmental weed in many parts of the world. A single viable seed escaping into a non-native ecosystem can have severe ecological repercussions. Given these considerations, the environmental benefits of using soap nuts are extremely debatable. Their efficacy in washing clothes remains uncertain, with no solid scientific evidence supporting their performance. On balance, the purported environmental advantages of soap nuts are questionable, and they probably don’t represent a better alternative to traditional detergents.
A Silver Lining
The silver lining is for those of you who have been using soap nuts all along and have been happy with the results. You’ve demonstrated to yourself that washing with effectively no detergent is good enough to clean your clothes. Not only do you not need detergent much of the time, but neither do you need soap nuts! Don’t believe me? Try a blind test at home and have someone else do one load of laundry with soap nuts, and one load with water only—you won’t be able to tell the difference!
Soap Nuts are Not an Alternative to Laundry Detergent
While soap nuts are a fascinating natural product with historical significance, their effectiveness as a modern laundry detergent alternative is unproven and likely limited at best. The complications around their sourcing, transportation as well as exporting pollution in a context where no scientific study has found them to be a viable alternative to laundry detergent is more than enough to bring into question their cleaning potential in a modern washing machine. The bright ray of sustainability sunshine in this exploration is that there is an eco friendly alternative – just wash with water only, and use washing detergent sparingly where water alone can’t do the job!