Food scientists assess nutritional weapons against COVID-19

By Rod Addy

- Last updated on GMT

Scientific papers on emerging aspects of nutrition and COVID-19 continue to be published
Scientific papers on emerging aspects of nutrition and COVID-19 continue to be published

Related tags Ingredients & nutrition

Selenium, zinc, Vitamin D and a healthy gut microbiota can all help fight the effects of COVID-19, according to scientists presenting at the British Nutrition Foundation's (BNF's) virtual conference Nutrition and COVID-19.

The conference, which took place on 24 November, also highlighted stress management and reduced stigma around obesity as important ways to tackle the virus's impact.

Professor Jason Halford from the University of Leeds presented evidence that people living with obesity had an increased risk of contracting the virus, hospitalisation, intensive care admission and death from COVID-19.

Halford shared data from a survey conducted by the European Coalition for People Living with Obesity revealing that 73% of those questioned were concerned about COVID-19 due to their weight. However, 43% had been comfort or binge eating since the beginning of the pandemic; 60% were experiencing low levels of motivation; and 60% were struggling daily with their mental health.

Stigma around obesity

He emphasised the negative impact that unusual life events – such as quarantine and lockdown at home – could have on weight gain and said many weight management services had been 'deprioritised' due to the pandemic. As such, he stressed the stigma around obesity, particularly on social media and in the press, was unhelpful in improving public health. Instead, strategies for supporting good mental health were needed to help the weight loss efforts of those living with obesity.

Prof Philip Calder of the University of Southampton, said a well-functioning immune system was key to providing robust defence against infections such as COVID-19. Among the many nutrients needed for immunity, he highlighted Vitamin D, zinc and selenium as being particularly important for anti-viral immunity. 

Calder emphasised the roles zinc played in the immune system, particularly its function in preventing multiplication of single-strand RNA viruses, like the novel coronavirus, by inhibiting enzymes they needed to spread. He explained that consumption of sufficient meat, poultry, cheese, shellfish, nuts, seeds or wholegrains could provide enough zinc without the need for supplements.


He said deficiency of selenium, a nutrient found in poultry, fish, eggs, nuts, seeds and organ meats such as liver or kidney, could impair immune responses. It could also increase susceptibility to viral infection, permit viruses to mutate and allow weak viruses to become stronger.

He referenced published research suggesting selenium supplementation in humans could help prevent viral mutation, which he said was very interesting when it came to coronavirus mutations.

Calder also shared findings from a paper released by German researchers looking at the relationship between selenium status and COVID-19 mortality risk. It suggested that low selenium status could be linked to more severe COVID-19. However, he cautioned that this was a small study and more research is needed to confirm this association.

Vitamin D

He presented data suggesting low levels of Vitamin D were associated with increased risk of COVID-19 infection, as well as hospitalisation. However, he stressed this was an association and so did not provide evidence of causation and there was insufficient data to recommend vitamin D for the prevention of COVID-19.

Professor Susan Lanham-New, of the University of Surrey, who reviewed the evidence on vitamin D, concurred. But she highlighted the importance of Vitamin D for bones and muscles in the context of widespread low Vitamin D status in the UK. She emphasised that all members of the public should take the recommended daily Vitamin D supplement of ten micrograms between October and March as a precaution to ensure good bone and muscle health.

The University of Reading’s Professor Glenn Gibson said the gut microbiome was a harbouring site for COVID-19 and clinical outcomes could be governed by the type of gut microbiome the patient had. For example, if the numbers of ‘good bacteria’ in an individual's gut were low, it might be more difficult for them to fight off the virus.


Gibson shared promising results from a recent Italian study into the effect of probiotics on the recovery of patients with COVID-19. The study involved two groups of people. The first (control) group was given hydroxychloroquine, antibiotics, and tocilizumab, alone or in combination. The second was given the same treatment, but with a specific formulation of probiotics added.

Within 72 hours, nearly all patients treated with probiotics showed remission of diarrhoea and other symptoms, compared to less than half in the control group. There was also reduced admission to intensive care units and fewer deaths. However, more research was needed to confirm these findings.

“Scientific papers on emerging aspects of nutrition and COVID-19 continue to be published,"​ said BNF science director Sara Stanner. "And one thing we can be certain of is that nutrition and maintaining a healthy body weight have important roles in keeping us healthy and, in turn, help us to protect against COVID-19 and the severity of associated illness.

Healthy, balanced diet

"Maintaining a healthy, balanced diet, including foods from all the main food groups, is the best way to help ensure you get all of the nutrients you need for a healthy immune system. However, everyone should consider taking a Vitamin D supplement especially during the winter months and also during the summer months if they are spending more time indoors than usual. 

“This year we have all faced a plethora of new challenges, and mental health issues are often the silent symptom of this pandemic. It’s therefore important for us all to recognise that we are living through an extremely stressful time, not to be too hard on ourselves, to look for support in finding ways to manage stress and to eat as healthily as we can.”

A growing number of resources with information and advice on diet and COVID-19 can be found on the BNF’s website​.

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