This winter, doctors are seeing a particularly persistent strain of flu circulating, driven by a mutated H3N2 virus - "subclade K" - a type of seasonal influenza A virus. Some are calling it "super flu" - hospital admissions have risen, and respiratory infections are lingering longer than many of us expect.

But viruses don’t overwhelm the body all at once. They meet us at our boundaries.

 

Why the respiratory barrier matters

Every breath passes through a finely balanced system lining the airways. This respiratory barrier is made up of cells, protective mucus, and immune proteins that work together to filter what gets through.

When it’s functioning well, it allows oxygen in, supports normal immune signalling, and limits access to the viruses and particles we inhale every day. During winter, factors like stress, poor sleep, pollution, and nutrient gaps can place extra strain on this system, making consistent support more important.

Where Lactoferrin comes in

Lactoferrin is a natural protein found in milk and in our own immune secretions, including saliva and the respiratory tract. It plays a role right at the surface of the airways, before infection is established.

Research shows lactoferrin can:

 

1. Interfere with flu viruses at the point they try to enter cells (block viruses from entering healthy cells)

2. Act early, before a virus can gain a foothold (give the body time to mobilise)

3. Support the structure and signalling of the respiratory barrier (bolster the respiratory barrier)

Rather than ‘boosting’ the immune system, lactoferrin helps the body do what it already does well, by supporting the barrier where exposure happens first.

 

 

Think of Lactoferrin acts like your body’s bouncer, supporting your defences this winter.

Regular lactoferrin intake has been linked in studies to fewer respiratory infections and shorter symptom duration. A study from 2019 found that lactoferrin can inhibit Influenza A virus infection (1) and another found lactoferrin to be a promising avenue to address viral infections:

"Lactoferrin, a vital component of the mucosal defense system, plays a crucial role in inhibiting viral infection by binding to both host cells and viral particles...This interaction enables Lactoferrin to keep viral particles away from their target cells, emphasizing its significance as a fundamental element of mucosal defense against viral infections.(2)"

For those looking to support their respiratory defences consistently through the season, options such as Leapfrog IMMUNE provide a daily source of lactoferrin alongside established measures like vaccination, rest, hydration, and good hygiene.

This winter we engage the systems that protect us every day - support the barrier, and let the body do the rest.

 

 

References

(1) Superti F. et al. (2019) 'Bovine Lactoferrin Prevents Influenza A Virus Infection by Interfering with the Fusogenic Function of Viral Hemagglutinin'. doi: 10.3390/v11010051.

(2) Shafqat A.(2025) 'A comprehensive review of research advances in the study of lactoferrin to treat viral infections' doi: 10.1016/j.lfs.2024.123340.