Lemon oil is cold-pressed from the peel rather than distilled, and it carries the citric acid and limonene that make citrus such an effective natural cleaner. On feet those same properties break down the built-up dead skin of a callus and lighten the discolouration that comes with it.
It is also astringent and antibacterial, which handles odour, and mildly anti-inflammatory, which is why the book reaches for it against gout and swollen feet as well as calluses.
There is one thing about lemon oil that genuinely matters and is easy to miss: it is phototoxic. Lemon oil on skin that then goes into sunlight can produce a serious burn.
