What is Phlegm?
Sputum, also called phlegm, is produced by your lungs to help keep the airways in your breathing system clear of germs and irritants. It is a normal mucus in your mouth, nose, throat, sinuses and lungs, although it is usually so thin it is not noticeable when you are healthy. When sick or exposed to too many particles, it can thicken and become much more evident as it traps them [1, 2].
Causes of Phlegm
Several health conditions can cause the body to produce more phlegm. Viral bronchitis, gastroesophageal reflux disease (GERD), chronic obstructive pulmonary disease (COPD), and congestive heart failure are all known to generate white phlegm [3]. Infections, allergies, or dehydration can thicken mucus and clump it [2].
Excess or thick-gauge phlegm is a symptom of:
Sometimes, phlegm is just a symptom of more serious underlying conditions not directly related to the respiratory system—for instance, in cases of heart failure or other complications. This is especially true if the phlegm is accompanied by shortness of breath and chest tightness [3].
Smoking and inhaling harmful particles, gases, or microorganisms can also cause an excessive production of mucus, which manifests in chronic cough phlegm syndrome [4]. In one study, cough alone was present in 17% of subjects, phlegm alone in 12%, and cough accompanied by phlegm in 31% [5].
Risk Factors of Phlegm
Phlegm production is part of a natural defence mechanism in the respiratory system that promotes the removal of contaminants. However, the conditions of its escalation and viscosity contribute towards symptoms of discomfort and illness.
The most critical risk factor for phlegm is smoking. Current smokers’ number of cigarettes smoked daily is a crucial risk factor for chronic phlegm. But, for example, a chronic phlegm smoker of 25 or more cigarettes per day has an odds ratio of 4.21 versus those of 1-14 cigarettes per day [6].
Phlegm is also influenced by dietary habits. They found that consuming fatty food is associated with an increased risk of having phlegm, with an odds ratio of 2.36. Other nutritional habits identified to increase risk were that of barbecued food (OR = 1.68), salty food (OR = 1.44), and sweet food (OR = 1.29) [7].
Secondly, the time of going to bed and rising in the morning are risk factors. In other words, an odds ratio of 1.87 for phlegm among those sleeping before midnight and rising after 8 am and an odds ratio of 1.43 for those who follow irregular sleeping habits [7].
Household dampness during childhood increases the risk of adult phlegm [8].
Furthermore, a variety of medical conditions can result in hypersecretion of mucus: viral bronchitis, gastroesophageal reflux disease (GERD), chronic obstructive pulmonary disease (COPD) and congestive heart failure [3].
Which Food Products Can Cause Phlegm?
Certain food products can stimulate the production of phlegm and exacerbate respiratory symptoms.
Dairy products, especially milk and cheese, can increase the amount of mucus produced, increasing the amount of phlegm [9].
Processed foods, often high in salt and fried foods, can also aggravate coughs and potentially increase phlegm production [9].
A diet rich in meats, sodium, and refined carbohydrates may increase the risk of developing a cough with phlegm [10].
Certain food allergens, including:
- Milk
- Egg
- Fish
- Crustaceans
- Nuts
- Wheat
- Soy
- Peanuts
- Peas and other legumes may sometimes affect the respiratory tract by causing phlegm production [11].
Sulfites, a preservative, can aggravate asthma in specific individuals and trigger the production of mucus.
They are found in:
- Wine
- Dried fruit
- Pickles
- Maraschino cherries
- Shrimp
- Bottled lemon and lime juice [12].
What Causes Phlegm After Eating?
Phlegm after eating can have several causes. One of the most common is acid reflux, in which stomach acid moves back into your oesophagus and irritates it, often leading to a cough and phlegm [13].
Another possible cause is aspiration pneumonia, which occurs when bits of food or liquid droplets get inhaled into the lungs, exposing the area to bacteria and potentially dangerous conditions. Symptoms of aspiration pneumonia include coughing up wet-sounding, green, or bloody mucus following a meal [13].
Food allergies may be the culprit as well. Eating something you are allergic to can trigger an immune reaction that results in a cough and phlegm production. Imagine that treating a cough brings about phlegm discharge. Food allergies may be the culprit. You know that if you eat something to which you are allergic, your body launches an immunological attack that will make you cough and may cause you to produce phlegm [13].
Finally, diet can also increase phlegm production. Eating too fast, not chewing food thoroughly, or eating during a coughing spell can all generate excessive phlegm after a meal [13, 14].