In separate saucepans, boil the swede and sweet potato in water for 15 minutes or until soft.
Drain and place back in the pans.
Add 10g butter and25ml ProZero to each pan and mash until smooth.
Season to taste.
ProZero is a food for special medical purposes and must be used under medical supervision. This recipe has been specifically designed for a low protein diet. Refer to labels for allergen and other product information.