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.
According to Ayurveda (India's ancient medical science for living a long and healthy life):
1. mixing fruit juice and milk is a poor combination for the digestive system to have to sort out
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.
According to Ayurveda like increases like so one simple rule to keep healthy whatever the weather is to adopt the law of gentle opposites - it's like balancing a set of scales...