Chinese Medicine considers that the immune system is strongly associated with the function of the internal organs, mainly the Lungs and Spleen. If these organs are well-balanced they will support the immune system (Wei Qi) and strengthen its function, which will prevent you from being easily affected by external pathogenic factors (colds, flu and other infectious or microbial diseases). For example, a group of people share a meal and some get sick, while others are more resistant; or some teachers say that when the children get the flu they will also get it. In these examples, those who get sick have lowered immunity or are deficient in Wei Qi. How is the immune system associated with the internal organs?

1. Lung
In Traditional Chinese Medicine, the Lungs dominate breathing and the skin, which is the first organ of defense. When the Lung function is deficient or compromised, the body will be more open to external pathogenic attack. In the case of Lung deficiency there are three possibilities:

the body is easily affected by wind, cold and heat;
the body is easily affected by external environmental seasonal changes;
the body is easily affected by others who are sick with the flu or a cold.
Common symptoms of lowered immunity due to Lung deficiency include sneezing, sore throat, runny nose, headaches, cough. These people are easily affected by the following conditions: hay fever, flu, cold, viral infections, asthma and pneumonia.

2. Spleen & Liver
In Traditional Chinese Medicine, the Spleen and Liver are the major organs that dominate our digestive system.  Where there is disorder of the Spleen or Liver, it can affect the transportation, digestion and absorption of the food.  This can leave the body prone to illness relating to the food we eat. In my clinical treatment, people with Spleen or Liver deficiency have a long list (up to 20 foods) that they just can't eat without experiencing adverse side effects. After strengthening the organs, they find that they are able to eat many of these foods again.

Common symptoms of Spleen and Liver deficiency that occur after eating certain foods include nausea, diarrhea, pain, uncomfortable or bloating sensation around abdominal area and headache. These people are prone to the following disorders: irritable bowel syndrome, gastro and food allergies.

Suggestions to boost your immune system and avoid illness:
avoid eating frozen or cold foods;
keep energy up and avoid exhausting yourself;
be sure to get enough sleep and rest;
avoid stress and emotional issues;
when you go out into a windy and cold environment, keep warm and protect yourself with clothing such as a scarf;
after washing your hair, make sure it is dry before going outside or before going to bed;
balance your body with natural medicine (such as acupuncture) before the change of weather so that your body can keep up with the seasonal changes without getting sick.