The science of green hair care

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</p> <p class="article-info"> <h1>The science of green hair care</h1> <p class="article-subhead">A push to move away from petroleum products — plus the perception that natural is gentler — has scientists lathering up new ingredients, from wood and fungus extracts to engineered proteins</p> <p class="article-byline"> <span class="author-byline">By Carolyn Wilke</span><br /> <span class="pub-date">12.18.2025<span><br /> </span></span></p> <div class="article-content"> <div class="article-text -drop-cap"> <p>Mika Sipponen, a materials chemist at Stockholm University, went for a swim in a murky lake. Afterwards, he noticed that his hair felt smooth — even without adding any hair product. The brownish water was rich in plant matter. So Sipponen wondered if one of the organic compounds — lignin, which is found in wood — could help to condition hair.</p> <p>His team made a concoction of lignin blended with coconut oil — and it worked. Experiments showed that it <a href="https://www.science.org/doi/full/10.1126/sciadv.adr8372">smoothed the surface of hair shafts</a> and reduced the force that it took to drag a comb through hair. And because lignin can be sourced from wood waste, Sipponen reasoned, hair products made from it would be more environmentally friendly than ones made with some of the standard ingredients.</p> <div class="article-image -caption-center"></div> <p>That research, published in <em>Science Advances</em> in 2025, is just one recent example of efforts to “green” hair care products, many of which have ingredients that are derived from non-renewable petrochemicals or that don’t degrade in the environment. The hair care market is worth tens of billions of dollars, and a growing number of consumers want products that have a smaller environmental footprint and are made from ingredients they perceive as being milder on the body. “Consumer awareness and pressure has made a real impact on the hair care market,” says Alexa Friedman, an epidemiologist at the Environmental Working Group in Washington, DC.</p> <p>The result has been a hodgepodge of efforts to incorporate bio-based compounds into products, including lab-made proteins and promising molecules from plants, fungi and even insects.</p> <h2>Remodeling and repairing</h2> <p>It takes a lot of chemistry to make effective hair products — shampoos that foam and carry away dirt or conditioners that leave hair feeling smooth. An average head hosts 120,000 to 150,000 hairs. At around shoulder length, that mop top makes for some six square meters of surface area.</p> <p>When people wash, condition and style their hair, they are spreading products across that large area — much of hair care is actually surface chemistry. It influences many characteristics of hair including luster, strength, softness and even the shapes that locks take.</p> <p>Zoom in on that surface and a strand of hair looks like a shingled snake. Mechanical wear and tear from harsh brushing and chemical treatments can rough up hair’s overlapping scales and change its feel and behavior. A thin layer of lipids — fatty compounds — coats the outside of healthy hair, acting as the first line of defense and contributing to hair’s luster, while the interior is mostly protein, particularly a type of keratin.</p> <div class="article-image -caption-center"></div> <p>Bio-inspired molecules that target keratin have already found their way into some products. An early keratin-repairing molecule came from the lab of biotechnologist Artur Cavaco-Paulo, who was investigating proteins that help the lungs expand, contract and exchange oxygen during breathing. In the lung lining, his team found protein fragments, or peptides, that seemed to have the right chemistry to stick to peptides associated with keratin, making them a candidate for hair repair.</p> <p>His team ended up identifying around 1,200 promising peptides. Experiments showed that one of them finds and sticks to dangling ends of hair where bonds in the keratin have been broken. “It really reconnects those,” says Cavaco-Paulo, who works at the University of Minho in Braga, Portugal, and is CEO of Solfarcos, a company developing new applications of peptides and proteins for pharmaceuticals and cosmetics. In 2013, this peptide became part of the commercial product known today as K18; evidence suggests that it improves the strength of hair, especially before and after dyeing or other harsh treatments.</p> <p>Now the researchers are <a href="https://knowablemagazine.org/content/article/technology/2024/compostable-plastic-from-natural-materials">looking to silk</a>, skin and insects for new protein ingredients. In one effort, they designed a protein that borrows part of its structure from silk and part from elastin, a protein found in skin, and then engineered the bacterium <em>E. coli </em>to make the protein. Applying it to hair <a href="https://pubs.acs.org/doi/10.1021/acsbiomaterials.5c01233">made the hair stronger and more elastic</a> compared with untreated hair samples, the team reported in the October 2025 <em>ACS Biomaterials Science & Engineering</em>. The protein may find use in leave-in hair products or hair masks that help maintain hair health during perming. The scientists are also looking at <a href="https://www.sciencedirect.com/science/article/pii/S2666386425004990#abs0010">molecules related to resilin,</a> an elastic protein found in various insects, as a way to protect hair from heat and mechanical damage.</p> <p>Cavaco-Paulo’s team has investigated other peptides from keratin <a href="https://pubs.rsc.org/en/content/articlelanding/2017/ra/c7ra10461h">that can straighten curly hair</a> without harsh chemical treatments. And formulations based on cellulose — molecules abundant in plant cell walls — might be used to <a href="https://link.springer.com/article/10.1007/s10570-024-06020-6">more gently curl hair</a>; early research finds the effect lasts through three washes with shampoo. “We think that this might be the direction to take our research,” Cavaco-Paulo says. So far, however, the results from these biomolecules don’t match those produced by harsh chemicals like ammonium thioglycolate and lye that are traditionally used to perm or relax hair.</p> <h2>Washing and conditioning</h2> <p>Many hair care products, such as conditioners, contain long-chained molecules called polymers that smooth jagged edges on hair protein scales to reduce frizz. These polymers are often positively charged and stick to the negatively charged surface of damaged hair.</p> <p>Although existing polymers work well, many are derived from petrochemicals. These include many polyquaternium compounds, a class of ammonium-based molecules that are favored for use in conditioners due to their positive charge. But used in hair products, they go down the drain and <a href="https://pubs.acs.org/doi/10.1021/acs.estlett.5c00880">may build up in the environment</a>. And some conditioners use synthetic polymers with a backbone of silicon. They make hair feel very smooth but microbes can’t easily degrade them, Cavaco-Paulo says; naturally made materials can break down more easily.</p> <p>Lignin, which can be sourced from agricultural and lumber waste, is one such ingredient, says pharmacist Carla Varela of the University of Coimbra in Portugal. The polymer also has antibacterial activity and provides some protection from the sun’s ultraviolet rays, making it an attractive addition to hair products.</p> <div class="article-image -caption-center"></div> <p>Using lignin extracted from acacia wood, Varela and colleagues <a href="https://www.sciencedirect.com/science/article/pii/S1385894725081847">modified the natural polymer</a> to make it positively charged so that it sticks more easily to damaged hair. That also made it more soluble in water, which is key for use in conditioners. The approach, reported in <em>Chemical Engineering Journal</em> in October 2025, doesn’t entirely avoid petrochemicals, which are the source of the chemical modifier for lignin, but it’s a good step, says Varela.</p> <p>Other researchers are investigating chitosan, a material derived from the shells of crustaceans and insects and the cell walls of fungi. Chitosan is easy to work with and doesn’t require harsh chemistry — it’s already found in some hair products as a heat protection and styling agent, says Eduardo Guzmán, a physical chemist at the Universidad Complutense de Madrid in Spain. To avoid harm to animals, fungal sources of chitosan are preferable, but fungal-derived chitosan molecules are too small to deposit well on hair. So Guzmán and colleagues are working to find the <a href="https://www.mdpi.com/2313-7673/9/9/534">right formulations</a> — by varying amounts of salt, for example, or tweaking the pH of the solution — to boost chitosan deposition.</p> <p>Scientists are also looking for substitutes for sulfates, which give shampoos their sudsy foam and are key to removing sweat, oil, dirt and built-up product. The long, hydrophobic tails of these molecules are attracted to oils and form little spherical shells around dirt and oil, trapping them. The molecules’ negatively charged heads allow water to easily wash the dirt-filled shell away.</p> <p>Sulfates have a bad reputation because they can be irritants for some consumers; plenty of sulfate-free shampoos are already on drugstore shelves. These include surfactants called sophorolipids <a href="https://aiche.onlinelibrary.wiley.com/doi/abs/10.1002/btpr.2682">that are sourced from fungi</a>, which cleanse gently and are used in some baby shampoos. Other sulfate replacements include alkyl polyglucosides — starchy, fatty molecules derived from plants such as coconut and palm oils, and glucose from corn and potatoes.</p> <div id="newsletter-promo-item"> <div class="newsletter-promo" style="background-color:#fff;border-top:4px solid #3c7680;border-bottom:1px solid #3c7680;"> <div class="newsletter-promo-img" style="display: grid;"></div> <div class="newsletter-promo-content"> <p><strong>Stay in the Know</strong><br /><a href="https://knowablemagazine.org/newsletter-signup" style="border-bottom:none;"><strong>Sign up</strong></a> for the <em>Knowable Magazine</em> newsletter today</p> </div> </div> </div> <p>Shampoos and conditioners can contain dozens of ingredients, and how these interact influences how well the products work, so researchers can’t typically just swap in one molecule for another. But because hair care products are so frequently used, changes that make them better for the environment could add up. After all, Varela says, “everyone washes their hair.”</p> <p>Still, Friedman of the Environmental Working Group cautions that it’s hard to know how green a product is because there is little <a href="https://knowablemagazine.org/content/article/food-environment/2019/blizzard-sustainability-labels">accountability for claims</a> about various products. (The Environmental Working Group has a verified program for personal care products that’s trying to bring more transparency.) And even if a product uses bio-based materials from renewable sources, it might still harm the environment: Palm plantations planted where forest was clear-cut, for example, harms important habitat and can add to carbon emissions.</p> <p>Even though consumers may seek greener alternatives, the most important criterion for them is still whether a product works. “The first thing is performance,” Cavaco-Paulo says. “That’s what people look for.” Scientists, in those murky ponds, forests and fungi, are looking too.</p> </div> </div> <link rel="canonical" href="https://knowablemagazine.org/content/article/food-environment/2025/science-of-green-hair-care" /> <meta name="syndication-source" content="https://knowablemagazine.org/content/article/food-environment/2025/science-of-green-hair-care" doi="10.1146/knowable-121825-2" />

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