Mastitis, which causes breast tissue to become sore and inflamed, is most common in breastfeeding women. Despite patchy scientific evidence, mums all over the world swear that slipping cabbage leaves in the bra can work wonders. Furthermore, a recent study at a Cairo maternity hospital suggests that cold leaves reduce the engorgement that can lead to mastitis. Most advocates agree that the leaves need to be chilled, and some recommend cooking them first to release chemicals from the cells. So how do the leaves work? The cold helps, especially when alternated with a warm compress. But the key may lie in the fact that cabbages contain glucosinolates. Enzyme action converts these to pungent isothiocyanates, collectively referred to as mustard oil. And mustard oil has long been used as a home remedy for swelling.