‘Healthy diet plays vital role in keeping Covid-19 at bay’

A researcher at the School of Human Development and Health, Faculty of Medicine, University of Southampton, has carried out a study to understand the role played by nutrition in boosting the immune system against Covid-19 infection.

The study, published in BMJ Nutrition, Prevention & Health, stated that many factors could alter the body's immune response. Ageing can be tied to a loss of immune system competence, called immunosenescence.

Philip C Calder, Faculty of Medicine, University of Southampton, Southampton, UK, noted that immunosenescence is characterised by reduced immune cells. This includes T lymphocytes, B lymphocytes, dendritic cells, neutrophils, monocytes, macrophages, and natural killer cells.

One factor associated with immunosenescence is a reduction of immune cells from the bone marrow, where these cells originate. All these processes that occur in old age could predispose older people to more severe Covid-19.

He further noted that obesity is also tied to a reduced immune response. Also, obese people experience impairments in the activity of helper T lymphocytes, cytotoxic T lymphocytes, B lymphocytes, and natural killer cells. They also have reduced antibody and interferon-gamma (IFN-y) production. This predisposes them to develop severe Covid-19.

Also, obese people may have a poorer response to vaccination. Obesity has also been linked to increased blood concentrations of many inflammatory mediators, a state of chronic low-grade inflammation.

Nutrition and immunity

The researcher wrote in his study that the immune system functions at all times, but specific cells become activated by the presence of pathogens. The activation leads to a marked increase in the immune system's demand for energy-yielding substrates, including fatty acids, glucose, and amino acids.

Calder believes that some nutrients, including vitamin A and D, are direct regulators of gene expression in immune cells. They play important roles in the maturation, differentiation, and responsiveness of immune cells.

He mentioned that antioxidants also play critical roles in protecting the body against oxidative stress. Classic antioxidant vitamins include vitamin C and E, including antioxidant enzymes such as catalase, glutathione peroxidase, and superoxide dismutase.

Vitamin A, B6, folate, C, D, and E, including trace elements such as zinc, copper, iron, and selenium, have been demonstrated to play key roles in supporting the immune system and reducing the risk of infections, he said.

"It would seem prudent for individuals to consume sufficient amounts of essential nutrients to support their immune system to help them to deal with pathogens should they become infected," Calder explained.

"Consumption of a diet of diverse and varied plant-based and animal-based foods that are consistent with current healthy eating guidelines would be best to support the immune system," he encouraged.