You Are What You Eat
Silk has been prized for over 4,000 years as a luxury material — lightweight, strong, and biocompatible, used in everything from haute couture to surgical sutures. But conventional silk has a glaring weakness: it shrinks and loses its shape after repeated exposure to moisture.
Now, researchers at Tohoku University have solved this problem not by chemically treating the fibers, but by changing what silkworms eat.
By adding plant-derived cellulose nanofibers (CNFs) to silkworm feed, the team produced silk fibers with 50% greater tensile strength and shrinkage after wetting and drying reduced to less than one-quarter of untreated silk. Even more importantly, these improvements persisted when the fibers were spun into yarn and woven into fabric — meaning the "super silk" can be used in real products.
A Simple, Sustainable Fix
"Our goal was to improve silk while preserving its natural advantages," said Associate Professor Hiroki Kurita of Tohoku University. "We were excited to find that simply changing the silkworms' diet produced silk that is both stronger and much more dimensionally stable in wet environments."
Other methods to improve silk's wet performance require toxic chemical treatments or extensive changes to production. In contrast, adding CNF to silkworm feed is practical and environmentally friendly. The CNFs themselves are derived from plant matter, making the entire process sustainable.
The findings were published June 25 in the Journal of Industrial Textiles.
Beyond Fashion
"Silk is not just for fashion — it is also used in a plethora of different industries you might not initially think of," Kurita noted. "For example, silk can be used in a medical setting as surgical sutures or a biomaterial to promote wound healing."
The team's previous work had shown that CNF-enriched diets could strengthen individual silk fibers, but they were unsure whether these benefits would survive the spinning, weaving, and finishing processes. The new results confirm that the structural improvements carry through to finished textiles.
The Road Ahead
The super silk retains silk's natural biocompatibility, breathability, and comfort while adding durability and wet stability. The researchers hope this sustainable approach will contribute to next-generation functional textiles — from medical materials that stay reliable after sterilization to outdoor gear that doesn't deform in rain.
In an era of fast fashion and synthetic fiber pollution, a simple dietary change for silkworms could help one of humanity's oldest textiles compete with modern synthetics on performance while remaining fully biodegradable.
