Can Lactoferrin, a Natural Mammalian Milk Protein, Assist in the Battle against COVID-19?

Abstract

Notwithstanding mass vaccination against specific SARS-CoV-2 variants, there is still a demand for complementary nutritional intervention strategies to fight COVID-19. The bovine milk protein lactoferrin (LF) has attracted interest of nutraceutical, food and dairy industries for its numerous properties-ranging from anti-viral and anti-microbial to immunological-making it a potential functional ingredient in a wide variety of food applications to maintain health. Importantly, bovine LF was found to exert anti-viral activities against several types of viruses, including certain SARS-CoV-2 variants. LF's potential effect on COVID-19 patients has seen a rapid increase of in vitro and in vivo studies published, resulting in a model on how LF might play a role during different phases of SARS-CoV-2 infection. Aim of this narrative review is two-fold: (1) to highlight the most relevant findings concerning LF's anti-viral, anti-microbial, iron-binding, immunomodulatory, microbiota-modulatory and intestinal barrier properties that support health of the two most affected organs in COVID-19 patients (lungs and gut), and (2) to explore the possible underlying mechanisms governing its mode of action. Thanks to its potential effects on health, bovine LF can be considered a good candidate for nutritional interventions counteracting SARS-CoV-2 infection and related COVID-19 pathogenesis.

Keywords: COVID-19; SARS-CoV-2; anti-viral; coronavirus; dairy; food; immunomodulation; iron-binding; lactoferrin; nutraceutical.

Figure 1

With age, the human body becomes less resilient and more vulnerable to (severe) disease due to inflammaging and gut dysbiosis. In healthy adults the immune system is fit, with the pro- and anti-inflammatory processes in balance, and the beneficial and pathogenic microorganisms in balance. The body is resilient to disease. During aging, the body has to respond to all kinds of harmful stimuli including viruses, pathogenic bacteria, a poor diet, toxins, and drugs, leading to inflammaging and gut dysbiosis; shifting the balance towards higher vulnerability to diseases like COVID-19, heart disease, diabetes, cognitive decline and frailty.

Figure 2

Physiological effects of LF (Blue) that support health of the 2 most affected organs in COVID-19 patients (Green).

Figure 3

Model illustrating the different stages of a SARS-CoV-2 infection in un-supplemented (left panel) and in LF-supplemented (right panel) COVID-19 patients. Based on the here presented data, LF protects the host from viral infections by prevention of binding and entry of SARS-CoV-2, and sequestering iron needed for viral replication. Furthermore, it indirectly affects virus attacks by having anti-oxidant effects and immune-, microbiome-, and intestinal barrier-modulatory characteristics.