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3. Designing for Digestion: Protecting Proteins Through
the Gut

The gastrointestinal tract is biologically engineered for
destruction. Its job is to break down anything unfamiliar—
proteins, microbes, food particles—into inert components
before they can cross the intestinal barrier. With stomach
acid at pH ~1.5, a cocktail of proteolytic enzymes (like
pepsin, trypsin, and chymotrypsin), and a gauntlet of bile
salts and microbiota, the digestive system is a hostile
environment for fragile therapeutics.

For conventional biologics, this has always meant one
thing: avoid oral delivery at all costs. Inject the protein,
bypass the gut, and protect it from digestion entirely.

But edible biologics flip this script.

They don’t avoid digestion—they’re designed to move
through it.
They use the rules of digestion as part of the delivery
system, protecting therapeutic proteins long enough to
reach the gut’s immunologic sweet spot.

The Plant Cell Wall as a Natural Shield

At the heart of this design is a simple truth:
Human enzymes cannot efficiently break down plant
cell walls.

Unlike the animal-derived excipients used in traditional
drug delivery, plant cell walls are composed of cellulose,
hemicellulose, and lignin—complex polysaccharides that
human digestive enzymes can’t fully degrade.

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