Anti-influenza virus activity of blackcurrant — A natural remedy for COVID-19?

With the current outbreak of coronavirus disease, it’s not surprising people are looking for ways to boost their immune system, and since there is no vaccine yet, it’s all we can do (besides minimising risks of contamination). I came across a number of studies conducted that might make your search of natural foods to boost your immune system a bit easier:

In one study the Department of Microbiology, at the Medical University School of Medicine, in Fukushima, Japan has researched the inhibitory effect of extracts of blackcurrant from New Zealand and Poland on 4 strains of influenza virus (IFV) by the inhibition of virus adsorption; pandemic flu 2009–2010, Hong Kong flu, Russian flu and influenza virus type B.

The inhibitory effect of the extracts of blackcurrant or blueberry on the infectivity of the virion were evaluated by the inhibition of virus adsorption on the cell surface (adsorption-inhibitory assay). Three percent solutions of the blackcurrant extracts from New Zealand and Poland were enough to disinfect more than half of pandemic flu and influenza virus type B, and 10% solutions from both regions disinfected all IFV strains completely.

Their previous study showed that the antiviral effect of the blackcurrant differed according to viral species. Here they showed that although the antiviral effect of Blackcurrant was slightly different within viral strains from one species, the extract of Blackcurrant could disinfect all of 4 IFV strains they examined. The extracts of blackcurrant showed definite potential for use as a disinfectant and antiseptic agent to prevent IFV infection. Check out the full study here.

A study in mice found that consumption of blackcurrant extract reduced virus accumulation and as a result mortality was greatly improved. Read more here.

This study showed that treatment of cultured cells with blackcurrant extract in the laboratory protected them from infection by influenza virus. Fractionation of blackcurrant extract has found that polyphenols are responsible for the observed antiviral activity. The compounds act by inhibiting haemagglutinin function. Haemagglutinin is the molecule on the surface of viral particles that binds the virus to cells it is infecting