A lignin-based conditioner may restore strands of hair

Hair conditioners typically contain dozens of ingredients, which are often sourced from petrochemicals or synthesized oils and fats. A new gel, made from a mere handful of components, looks to lignin from wood to protect and restore hair (Sci. Adv. 2025, DOI: 10.1126/sciadv.adr8372).

Heat and chemicals can damage hair, roughing up its surface and oxidizing its outer fatty acid layer so that the hair surface becomes negatively charged. Off-the-shelf hair conditioners come to the rescue with positively charged quaternary ammonium salts. These glom onto the hair’s surface and bolster its fatty acid coating. But creating these oleochemicals can require harsh chemicals or carbon-intensive processes, says Mika Sipponen, a materials chemist at Stockholm University. Additionally, conditioners often contain moisturizers, emulsifiers, antioxidants, stabilizers, fragrances, and compounds to block UV light.

But a great hair day doesn’t always require fancy products. Sipponen recalls his experiences after taking a dip in lakes filled with brown-hued water. “It’s amazing,” he says. “When you swim, you don’t need any hair conditioner.” The lake water likely contained polyphenolic compounds from the degradation of lignin-containing plant matter. It inspired him to create a simple conditioner based on lignin. Lignin has antioxidant, UV-shielding, and surface-active properties. “This is basically ticking all the boxes.”

His team whipped up conditioners containing two types of lignin, water, a salt, and either coconut oil or sunflower oil. By experimenting with various lignin and oil concentrations, they landed on a shiny, black gel. The substance contained 6% oil and resembled the thickness and spreadability of commercial conditioners. “It actually has quite a bit of oil,” says Ievgen Pylypchuk, a materials scientist at Stockholm University. “But when you touch it, it doesn’t feel greasy.” The gel stayed stable for over a year.

Scanning electron microscopy suggests that the lignin-based gel and a commercial conditioner may restore hair in similar ways. Both smoothed human hair damaged by hydrogen peroxide. With a setup that pulled wet hair through a fine-toothed comb, the team observed that the lignin gel reduced the combing force by 13% as compared with unconditioned hair—close to the benefit provided by the commercial product. In a test of antioxidant activity, hair treated with the lignin gel outperformed hair treated with store-bought conditioner. That result suggests that the wood-based product may be better able to protect hair from damaging oxidants that can arise from UV light exposure. Also, the gel washed clean from filter paper and pig skin, so it shouldn’t stain towels or skin.

“It’s an important work,” says Maria Graça Rasteiro, a chemical engineer at the University of Coimbra, noting the need for alternatives to petrochemicals and nonbiodegradable substances in cosmetics. The researchers could gain a better understanding of the lignin’s interaction with hair by studying its adsorption, she says. Rasteiro’s team is also working on lignin-based hair conditioners. In work not yet published, they have modified the lignin with amino acids to tune their conditioner’s staying power on hair, she says.

Before lignin-based hair care can reach the market, the researchers will need test it for safety and the potential to irritate skin or eyes. And Rasteiro wonders whether the public will be willing to purchase an unusual black gel to condition hair.

Sipponen sees yet more potential for lignin. Lignin has surfactant properties that are also needed for shampoo, he says. “It would be nice to see if it works as a two-in-one wash and conditioner.”