Factors that can influence the thickness of the secretions

Question

Dear expert-team,

Are there conditions apart from medication that can make secretions more tenacious or more liquid? For instance type of food, weather conditions, etc?

Answer

Dear questioner,
To answer the questions whether conditions other than medication change the viscosity of the secretions, first some explanations about secretions. Secretions or mucus play an important role in our defense system. Inhaled bacteria, dust and other substances are trapped on the mucus layer on top of the airway. That mucus layer is cleared from the airways several times a day by the action of cilia so that the airway stays free of infection and noxious particles.
Mucus consists of specific proteins, fats, particles responsible for defence against disease causing organisms, ions (think of those as ‘salts’) plus water. In people with chronic infection of the airways (such as for instance CF), there is an increase in mucus production as part of the reaction of the inflamed airways. Also the composition of the mucus changes so that the mucus becomes more viscid. When there is a lot of infection, the mucociliary ladder described above is damaged or can no longer cope with the amount of secretions and it can happen that mucus from the airway is being coughed up. We then say that this person produces mucus or sputum. In case of CF the composition of the mucus is definitely abnormal. Secondary to dysfunction of the CFTR channel the mucus is more viscid (read more about this in questions on the cause of CF), some of the specific compounds that make up the natural defense in the lung are missing and more inflammatory products are present. In addition the numerous white blood cells (leucocytes) present in the secretions secondary to infection and especially the break down products of these, such as DNA will make the mucus of CF patients extremely viscid. It is very difficult to cough up this viscid sputum.
Sometimes people say that ‘milk makes you produce more secretions’. That is not correct. After drinking milk, you might have the feeling of a bit of stickiness in your mouth but milk does not influence the composition nor the production of mucus in the airway. There are really very few products that change the viscosity of the mucus. Even for medicines specifically designed to change the viscosity of the mucus such as carbocysteine there is little proof that they have a beneficial effect when the patient takes them.
Also on the influence of weather conditions little is known. In a Finnish study it was shown that people will cough up more sputum at temperatures below 5°C than at temperatures above 0°C.
In the treatment of CF we now use products that attract water and thereby make the secretions less viscid. Examples of these are strong salt solutions (hypertonic saline) and the natural sweetener mannitol. But since they are investigated in treatment, you can also consider these products medicins.
Kind regards
Dr. P. Van De Wijdeven, Dr. F. Vermeulen

24.11.2009