Ginger's active compounds — gingerols and shogaols — are vasodilators. They widen blood vessels near the skin surface, which is why a ginger soak produces a genuine, spreading warmth rather than the sensory illusion menthol creates. For cold feet that is the difference between feeling warmer and being warmer.
It is also a real anti-inflammatory, well enough established that it turns up in the medical literature on arthritis rather than only in folk medicine. That is why the book reaches for it against arthritis, gout and swollen feet — three problems where inflammation is the actual mechanism.
Fresh root is more potent than dried powder, and the difference is worth the extra minute of grating.
