Not just any old vegetable curry, go for Simply Organic's Pure & Pronto Organic Thai Curry with Green Lentils, £1.88 for one serving from Tesco. It's a healthy microwave meal that contains three portions of veg. It's the ultimate easy immune booster, packed with antioxidants that help boost your defences. Also low fat and with no added salt, with only 241 calories. Spicy foods are not only warming, but can help relieve nasal congestion too.
A rich source of beta-carotene which has been found to increase the activity of natural killer cells. They are part of your body's surveillance system against viruses. Beta carotene absorption is improved if red peppers are cooked, so buy your own and stir-fry with other veg. Or try Asda Red Pepper Spiralle ready meal, £1.78 for 400g, for a quick and tasty lunch which will also bolster your protection against colds and flu.
Just one liver meal a fortnight will top up your levels of vitamin A. This is important for keeping mucus, the natural germ barrier inside your nose and throat, healthy. If you think you don't like liver, try Waitrose Easy Lamb's Liver with Shallot sandwiches instead. Liver pate's also rich in vitamin A.