You may not even think about phlegm, also referred to as mucus, until you're producing more than normal due to an illness. But phlegm does more than help you empty your tissue box. It acts as a lubricant to help food pass through your digestive system, and it traps pollen, dust and mold in your lungs to keep you healthy. Under normal circumstances, food should not make you produce more phlegm. However, if you have a food allergy or consume a food that causes your body to produce histamine, your body may react by increasing phlegm production.
In addition to hives and an upset stomach, your body may also produce more phlegm when exposed to a food allergen due to an increase in histamine production. Any food can cause an allergic reaction, according to Food Allergy Research and Education, but the most common food allergens include milk, eggs, tree nuts, fish, shellfish, wheat and soy. Other potential foods that may increase phlegm production due to an allergy include corn, gelatin, seeds, spices or meat.
Foods that are a natural source of histamine that may also cause a reaction that increases phlegm production. These foods include alcohol, anchovies, avocados, aged cheeses such as Parmesan, smoked or dried meats, sauerkraut, mushrooms, spinach and yogurt.
Certain foods also cause your body to produce more histamine because of a food intolerance. Foods that may cause your body to produce more histamine include fish, chocolate, soy sauce or processed meats.
If you don't have any food allergies or intolerance and you're producing phlegm that's causing your nose to run after you eat, you may have a condition called vasomotor rhinitis or nonallergic rhinitis. The cause of this condition is not known, but certain types of food may trigger a reaction, including spicy foods. Treatment includes avoiding the trigger, according to MedlinePlus. Keeping track of what you eat and how your body reacts may help you pinpoint foods you need to avoid.
Truth About Milk
It is commonly believed that milk increases phlegm production in the lungs, and many people may avoid drinking milk for this reason, especially when sick with a cold. However, a 2005 article published in the Journal of the American College of Nutrition reports that milk does not cause your body to make more phlegm or cause congestion. Of course, the exception is if you're allergic to milk.