I swear by a glass of fresh fruit juice every morning with a teaspoon of honey. My juicer is a heavy duty one which keeps all the fibre and I love it. It may not really ward off the colds, but makes me feel better and if I do get a cold, before bed I soak a piece of ginger in boiling water, add a smigeon of whisky or dark rum, a drop of blackcurrant cordial and another spoon of honey, maybe stirring in a pinch of cinnamon and a soluble paracetamol. Maybe the placebo effect, but makes me feel better. My local chemist has packs of Rowse's honey sachets perfect for purpose.