Researchers have produced vegetables from human hair

The keratin-based substrate is biodegradable, eco-friendly, sustainable, and could revolutionize urban farming.
Deena Theresa
Scientists at NTU, Singapore, grew crops from discarded clumps of hair.
Scientists at NTU, Singapore, grew crops from discarded clumps of hair.

NTU 

  • Scientists at NTU grew crops from discarded clumps of hair.
  • Hair served as the growth medium instead of soil.
  • The research is crucial to a more sustainable form of urban farming.

In a lab at Nanyang Technological University (NTU), Singapore, scientists have been growing crops — leafy vegetables, micro greens, rocket leaves, and the Chinese cabbage bok choy — using discarded hair collected from salon floors.

Doesn't sound too appetizing, does it?

Allow us to explain. Researchers created the growth medium used in their urban farming —known as hydroponics substrates—using keratin extracted from the human hair.

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In hydroponics, crops are grown without soil. Instead, a substrate, such as coir or rock wool, that acts as a support structure and reservoir for water and nutrients is used to help grow crops for human consumption.

Why is this research important?

Current commercial hydroponic offerings such as those made from rock wool, polyurethane, and phenolic foams are not sustainable and do not provide nutrition to plants.

"People have tried natural options such as cellulose. But, the key difference here is that we're using a protein that becomes part of the nutrient mix when it degrades. This is something that other material platforms do not provide, even if they're degradable," Professor Ng Kee Woei, associate chair at NTU's School of Materials Science and Engineering (MSE), who led the research, tells Interesting Engineering (IE) in an interview. "That's essentially the most critical difference."

Researchers have produced vegetables from human hair
(From left to right) Dr. Pan Xiaoyong, Research Fellow, Professor Hu Xiao, Professor Ng Kee Woei, and Dr. Zhao Zhitong, Research Fellow, NTU School of Materials Science and Engineering, holding up various raw materials (such as human hair and keratin solution) and their keratin-based hydroponics substrate.
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Their findings were published in the scientific journal ACS Sustainable Chemistry & Engineering.

IE had a ton of questions about the fascinating project. And Professor Ng was eager to delve into the nitty-gritty of the research, which could someday help alleviate global hunger and add to a robust food security system.

This interview has been lightly edited for clarity.

Interesting Engineering: Your background lies in mechanical engineering and medicine. How did that translate into agricultural systems and food security?

Ng Kee Woei: I had been working with different types of biomaterials for biomedical applications - looking for novel materials that can be used in the human body. My focus was to find sustainable materials that can satisfy all the classical criteria of biomaterials - compatibility, and evoking minimum immunological reactions. I found hair keratin interesting, so I did a lot of work extracting substances from hair and using them for various medical purposes.

In the last few years, I started to realize the impacts of climate change, and the issue of food shortage. I wanted to use my knowledge in the biomedical space to solve some of the apparent problems that we're facing. On a fairly serendipitous occasion, I had a chance to visit an urban farm in Singapore wherein the manager spoke about problems with substrate materials used for seed germination. I felt it was a problem that material scientists and engineers could solve.

Researchers have produced vegetables from human hair
An urban farm in Singapore.

So I started looking into the literature and realized that even though some work had been done in terms of creating alternative forms of sustainable substrates, not much has been done in terms of creating something smarter in nature. Smarter in the sense that it can respond to the environment, release nutrients, and be degradable at the same time. It follows the concept of what we have been traditionally doing in the biomedical space - an implant that can potentially release drugs, a platform that cells can grow on and mature, and form tissue.

At the time, there was a collaborative program on sustainable nanotechnology between NTU and Harvard. I made use of that platform to start this work on hydroponic substrates.

Researchers have produced vegetables from human hair
A graphical representation of the process.

IE: Can you walk us through the process?

NKW: My students and staff members collected discarded hair from hair salons in the neighborhood. In the lab, we mechanically cut them down to smaller strands of hair and thoroughly washed them. Once clean, we begin the first step, called delipidization in which the lipids and the natural sebum coating on the hair are removed. Once done, we introduced chemicals to dissolve the hair structure which can extract the keratin out of them. After the process, the keratin is left behind in soluble form. This is the starting material that we use to start making the substrates.

However, keratin is not strong enough by itself to form a substrate. So we mixed it with cellulose fibers (extracted from softwood pulp) to strengthen its structure and improve its water-swelling capabilities. Later we dried the substance, which solidifies the material and forms it into the sponge (the base). There are a lot of things within that process that can be tweaked to make sponges with a range of different physical-mechanical properties, chemical compositions, and nutrient content as well.

Researchers have produced vegetables from human hair
The researchers collected discarded clumps of hair from salons.

IE: Were there unexpected outcomes?

NKW: The plant response to the substrate was unexpected. Now, I'm not a plant expert, and I'm working with plant biologists who can hopefully help us look more into the mechanism of what's happening. But we noticed that every plant responded differently when cultivated in these sponges. I thought that the general nutrition for some of the plants was similar, at the earliest stage. But now, I think there's much more to it in terms of how different plant species respond to what is provided to them in the sponges.

There are a lot of things to study. And obviously, this also means that there is good potential for us to develop different types of sponges to suit different needs of different plants and different crop types. That's what's exciting for me moving forward. Because it's not going to be a one-size-fits-all solution, but a potential multi-varied product line that can be used for different crop types.

Researchers have produced vegetables from human hair
The team grew crops such as microgreens and leafy vegetables, including the Chinese cabbage bok choy and arugula leaves, from the keratin substrate.

IE: The substrate is sustainable, biodegradable, eco-friendly, and becomes a source of nutrients for the plants as it degrades. What are the drawbacks?

NKW: I think the current drawback would be the lack of a sustainable supply of keratin as raw material. Of course, somebody can set up a factory and start to extract keratin, from hair or feathers and supply them to companies that can make these substrates. But it is a case of not having an industry to support the case of setting up such a factory. And therefore, it's a chicken and egg problem. Even if the material works very well, if you can't get a sustainable supply, or somebody to supply the raw material consistently, then it's still not going to take off, from the commercial aspect. We can also think about setting up such a plant ourselves, and assuming that we have the investment and commercial interest, this is of course possible. But essentially, not having a consistent and good quality supply of keratin is probably the largest limitation of making this technology more widespread.

Researchers have produced vegetables from human hair
A farmer at a hydroponic farm.

IE: How did your peers or colleagues react to the study?

NKW: Since my colleagues are scientists, they appreciate the rationale and potential usefulness of this approach. But when I talk to external people, my friends, family, or even other professionals, their comments are along the lines of how we are eating our hair. It's probably an issue of psychological acceptance because we normally associate waste hair with something dirty, yucky, and gross.

But I always try to clarify that we are not using the original hair structure. We're completely dissolving that structure and extracting only the proteins out of them. That's one important, differentiating fact that needs to be understood. The other rationale that I quote is that, for the longest time ever, we have been putting all kinds of waste material in fertilizers. So I think it's an issue of perception. Eventually, if this technology picks up and gains commercial interest, we will have to be very clear in how we communicate to the public.

Researchers have produced vegetables from human hair
The scientists believe their study could make urban farming sustainable.

IE: To what extent can this research help urban agriculture?

NKW: Urban farms that are primarily based on hydroponics culture are of great interest in modern cities. And I think hydroponics could be one of the most important ways for us to increase food production at a scale that is needed without using vast land areas that traditional agriculture requires. But, the waste generation from hydroponic-based urban farms is a concerning area.

After talking to these farmers, I realized that these substrates that are being used are a significant source of solid waste that urban farms produce, as urban farmers mostly go for very cheap options - and tend to fall back on materials like polyurethane foams. There is a significant waste stream that is unsustainable for urban farming. And so, if we can replace that with something smarter and more sustainable, I think that's one way to reduce the carbon footprint of these urban farms, especially if we think about trying to upscale this research.

IE: What is the next step? What are you currently working on?

NKW: I'm trying to come up with different versions of these sponges - ranging from various physical properties to tuning the degradation time needed to suit different crop types. Some crops have very short growth cycles, lasting four to six weeks or less, while others have longer growth cycles, lasting, say, six to eight weeks or more. For crops that may be harvested often, you may want to have a sponge that can last a lot longer. I'm currently working on those.

Simultaneously, with the most basic version that we have, I'm hoping to start testing out the feasibility of using those for some existing crops on a commercial farm. I'm in touch with some interested industry farmers; We will, of course, start testing on a smaller scale. The point is to use these in a real atmosphere inside the farm, not within a laboratory setting. I want to subject the sponges to outside elements and see how they behave. I'll then have a better idea of the ways to tweak the sponges.

Professor Woei adds that we need to think broadly, beyond our comfort zone. "Only then we can further exploit resources around us that we're not thinking of, or reading about. We haven't really looked at the other waste streams that we've been producing as a society. It would be helpful if everyone could look into our own lives and check what we can reuse and recycle to achieve greater sustainability in all aspects of life."