Dr Nidia Rodríguez-Sánchez, Lecturer in Physiology and Nutrition, Faculty of Health Sciences and Sport, University of Stirling

What role does nutrition play in supporting our immune system, and what impact is the current pandemic having on our nutrition? Dr Nidia Rodríguez-Sánchez explores some of the key issues in our COVID-19 bite-sized lecture available to watch online, and transcribed below.

Hello, I am Nidia Rodríguez-Sánchez, I am a lecturer in Physiology and Nutrition at the University of Stirling and today we will talk about Nutrition and COVID-19. I wrote and recorded this talk on May 16th, 2020, I used the information that was available at the time. It is also important to highlight that I am not intending to cover everything related with this topic.

We will talk about what coronaviruses are, the factors that will be affecting our immune system, the relation of nutrition and COVID-19. What might be the long-term impact of the pandemic in the health and nutrition status, and we will talk about some recommendations.

What are coronaviruses?

Coronaviruses are large family of viruses that usually cause mild to moderate upper respiratory tract illnesses like the common cold. However, three new coronaviruses have emerged from animal reservoirs over the past two decades to cause serious and widespread illness and death. There are hundreds of coronaviruses with most of which circulate among such animals as pigs, camels, bats and cats. The third novel coronavirus to emerge in this century is called SARS-CoV-2 and it causes Coronavirus disease 2019 which emerged from China in December 2019, and was declared a global pandemic by the World Health Organization on March 11th, 2020.

Factors affecting our immune system

There are many factors that will be affecting our immune system, and in this talk we will focus on these four: the nutrition or the diet, the gut microbiome, obesity, and age. Age will be related to COVID-19. There is an effect called immunosenescence that is related with changes in the immune system associated with ageing. It has been observed that older adults can have weakened immune systems and these will be translated in a higher rate of infections and a higher number of illness, a higher number of admissions to the hospital, and increased use of antibiotics and that will be translated into antibiotic resistance, a worst or an impaired outcome from interventions and surgeries and also in an increased number of deaths.

It has been observed that obesity is a risk factor for COVID-19. Some of the increased risk of severe COVID-19 associated with obesity could be due to people having other chronic conditions and the chronic state of inflammation that can impair the immune system of patients. We are presenting some data from a research done in France and just as a reminder, the BMI or the body mass index is a person’s weight in kilograms divided by the square of their height in meters.

In this study, they observed that the need for mechanical ventilation increased with increasing BMI. So, the fact that the patients were obese increased the need of having a mechanical ventilator. We don’t know exactly what role obesity plays in the severity of COVID-19 symptoms, but the mechanisms are likely to be multi-faceted since obesity is a result of a complex interaction between hormonal, behavioural, social and environmental factors.

If we have an appropriate nutrient supply, an appropriate or adequate nutrition status and also an adequate immune function, that will be improving the defence against pathogens. We also need to highlight that no food, or nutritional supplement will be preventing someone getting coronavirus. It is important that we are providing our body with the nutrients that are needed to keep a healthy or a well-functioning immune system.

Now, the gut microbiome is very important for our immune system as well. The microbiome are all the microorganisms that normally are living in our body. When we talk about the gut microbiome, they are the microorganisms that are living in our intestine. And it is important to ingest probiotics that will be providing lactobacilli or bifidobacterial. It has been observed that this will be improving the immune responses. It will be increasing the response to seasonal influenza vaccination. It will be reducing the incidence and duration of diarrhoea in children and also the intake of probiotics reduced the incidence and severity of respiratory tract infections, mainly in children.

The importance of nutrition

There are some nutrients that are related with well-functioning immune system and we will talk about some of them. Vitamin D: it has been observed that a low status of vitamin D is associated with reduced immune response. Our main source of vitamin D is from sunlight on our skin. Food sources include oily fish, eggs, and fortified cereals. Also, some ethnic groups can have a deficiency in this nutrient. Such as the people with a darker skin, and the groups that do not eat fish, or do not eat Vitamin D food sources. In those cases, it might be recommended to have a supplement of vitamin D. Also, when people are self-isolating or when they are staying at home because of the lockdown, it is important to consider the use of a vitamin D supplement.

Vitamin A will be also playing an important role in our immune system. It will be found in foods such as liver, whole milk, and cheese, and some fruits and vegetables, for example, in carrots or in yellow peppers and in darker green leaves.

Vitamin C will be helping with the immune cells to attack pathogens and it also enables us to clear away old immune cells from the site of infection. We can find it in citrus fruits, green vegetables, peppers, and tomatoes. Vitamin C supplementation can be an option to prevent and support the immune system and to help us in case of being at risk of COVID-19.

Selenium is fundamental to produce new immune cells, and it can help to strengthen response to infection, and we can find it in nuts and seeds, and in sunflower seeds. Zinc will be also important because it will improve the immune function related to viral responses. We can find it in meat and poultry.

The impact of COVID-19

After the coronavirus lockdown measures that that were put in place, most of the people changed their eating and cooking behaviours. It has been observed that people started baking more and cooking more at home. Some surveys have observed that people are willing to have a better or a healthier lifestyle after COVID-19. But these will also depend on the sociodemographic status of the people. For example, in the middle upper class, it is expected that people will be embracing and keeping this active nutrition, meaning that they will be active, they will be exercising, they will be including different food to boost their health and it is believed that this trend will be continued in 2020. Also, there will be an increase in the ingestion of organic food and in protein that is coming from the plants instead of animal-based protein.

Another study was undertaken in the Netherlands had 1030 Dutch participants, and reported that 10% of the respondents said they started eating healthier. Also, they reported that hygiene habits were improved. Some of them reported that they were drinking less alcohol than before the coronavirus measurements started. Some of also them reported to be eating unhealthier due to the situation. 20% of the respondents reported that they were snacking more, and a third of the participants also reported that they were paying more attention to their weight while 5% percent of the respondents indicated that they have started to lose weight. We need to keep in mind that just because people are eating at home, this doesn’t mean that they are eating healthier.

Now, what is happening in the lower socio-economic groups? There are consequences of the pandemic that are having an important impact on their health. For example, the unemployment, the deprivation of education and inadequate nutrition and mental health issues that are widening their health inequalities.

COVID-19 does not treat us equally. Undernourished people have weaker immune systems and may be at greater risk of severe illness due to coronavirus. At the same time, poor metabolic health, including obesity and diabetes, is strongly linked to worse COVID-19 outcomes, including a higher risk of hospitalisation and death. COVID-19 has also tested our food systems and they have exposed their vulnerability and weaknesses as well. Good nutrition is an essential part of the individual’s defence against COVID-19 and this is highlighted with the nutrition resilience. Resilience is not just about is resistance to change and going back to how things were.  It can involve making adjustments to respond to new stressors or even making considerable changes to a system, be it the household, community or a country. And there will be three capacities on this transformation or this process, so it’s the absorptive coping capacity, the adaptive capacity, and the transformative capacity. Resilience is the result of not just one, but all of these capacities, and will be responding at different degrees depending on the changes or shocks.

Recommendations

Some recommendations: keep a healthy diet, balance food intake, try to include food from all food groups: fruit, vegetables, nuts, seeds, pulses and also some animal based foods such as oily fish, and some meat. Try to keep active, keep your exercise habits, try to reduce the alcohol intake. The idea is to improve your eating behaviour and therefore your lifestyle.

Remember, there are no foods or supplements that can prevent you getting infected with coronavirus. Each micronutrient will have a very important role in the immune system. Supplements cannot substitute a healthy diet, it is something that we need to be doing day after day to keep ourselves healthy and to keep our immune systems in an optimal condition.

Thank you very much for your attention.

Dr Nidia Rodríguez-Sánchez, May 2020