Nutricia pre Op Nutricia pre Op is designed to switch patients from a fasted to a fed state prior to surgery & has been shown to moderate metabolic responses to surgery, improve well-being, decrease post-operative insulin resistance & attenuate loss of lean body mass. Nutricia pre Op is a clear, non-carbonated, lemon flavoured, carbohydrate drink that provides 0.5kcal/ml & is safe to use up to 2 hours before surgery. Nutricia pre Op is gluten, lactose, fat, protein & fibre free.