Conventional wisdom states that drinking milk causes an increase in phlegm. Scientists have generally dismissed the notion, though, since experiments do not seem to bear it out. In one study, researchers noted that even people who were inoculated with the common cold virus did not show any increase in symptoms when they drank milk.
But a new report suggests that those earlier studies suffered from a critical flaw: not all milk is the same.
Certain breeds of cows produce milk containing a protein called beta-CM-7. This protein can stimulate mucus glands in both your digestive- and respiratory tracts.
Milk containing the beta-CM-7 protein could therefore very well stimulate phlegm -- particularly in people who suffer from chronic lung conditions.