Several RCTs and prospective studies show lactoferrin supplementation reduces upper respiratory tract infection (URTI) frequency and duration in adults. The mechanisms operating at the nasopharyngeal mucosa — direct antiviral HSPG-blocking, bacteriostatic iron sequestration, and NK cell activation — are particularly active at the primary infection site of respiratory viruses.

Should I increase lactoferrin dose when I feel a cold coming on?

Yes. Increasing lactoferrin to 400–600 mg/day at the first sign of respiratory symptoms (within the first 24–48 hours) provides the strongest antiviral benefit by flooding mucosal surfaces with the protein during active viral replication.

Is lactoferrin better than vitamin C or zinc for colds?

Lactoferrin, vitamin C, and zinc have different mechanisms and are complementary. Lactoferrin provides direct antiviral and bacteriostatic effects; vitamin C supports immune cell function; zinc provides ionophore-mediated antiviral activity. Combining all three at symptom onset provides the broadest antiviral coverage.