Smokers can reduce the risk of bronchitis by drinking milk. This is because the vitamin A in milk can protect the walls of the trachea, reducing the chance of inflammation. Correspondingly, doctors advise workers exposed to dust to drink more milk, as the protein, vitamin A, and C in milk have a protective effect on the respiratory mucous membrane cells. Moreover, milk can detoxify and lubricate the intestines, reducing the damage to the gastrointestinal tract from certain factors.