Inside every human body, a quiet negotiation unfolds between the food we eat and the microbial communities that transform it into compounds capable of protecting or harming us. Two new studies from Ludwig Princeton have clarified, with unusual precision, how plant-based diets tip that negotiation toward health — not only through fiber, as long assumed, but through a newly recognized class of indigestible plant proteins. Perhaps more strikingly, the research reveals that our own cells are active participants in producing metabolites science had credited entirely to gut bacteria, suggesting that