I've just read an article on a popular health content web site that is offering a diet to beat colds and flu.
It recommended orange juice, fortified cold milk and cereal for breakfast as a good and immune boosting start to the day.
and 2. you don't eat cold things (especially dairy things) if you want to avoid a cold.
It's very simple really - cold increases cold and heat increases heat.
If the weather's cold and you don't want a cold - eat warm, light, easy to digest, nourishing foods like soups, dahls, rice and vegetables, add a little ginger, cumin and turmeric to your cooking to boost immunity, aid digestion and warm the body.
If you're steaming your way through a hot summer, lay off the chillies to reduce the risk of skin irritations and allergies, or just general overheating.
Another home remedy for cold: Boil eucalyptus leaves or ginger in a quart of water and inhale steam.