Immunity

The immune system plays an important role to protect the host from invading pathogenic organisms like bacteria, viruses, fungi, parasites etc. There are numerous kinds of specialized cell types, communicating molecules and functional responses that help the immune system to carry out its function smoothly. Although the immune system remains active all the time, its activity becomes times fold if the host catches an infection, which further demands an increased rate of metabolism, more energy sources, a greater amount of substrates for biosynthesis and regulatory molecules, which all ultimately are derived from the nutritious diet. 

A great variety of vitamins like A, B6, B12, folate, C, D and E, and trace elements like zinc, copper, selenium, iron are being known to play a key role in supporting the human immune system and reducing the risk of infections. Additionally, amino acids and fatty acids too help in strengthening the immune system. These molecules render the body the defence for antibacterial and antiviral activity, with zinc and selenium particularly important for the latter. Thus its reasonable for individuals to consume sufficient amounts of essential nutrients to support their immune system to fight pathogens that infected them. 

The immune system can be best supported by consuming a diet consisting of diverse and varied plant-based and animal-based foods that are consistent with current healthy eating guidelines. Human trials have reported increased intake of some micronutrients like vitamins C, D and E and zinc and selenium is needed to optimally support the immune system. This can be fulfilled through diet alone or supplementation too might be considered. 

Gut microbiota has shown an important role in educating and regulating the immune system. Gut dysbiosis remains an important feature of many diseases like infectious diseases and also COVID-19. Achieving a healthy microbiota via Dietary approaches has proven beneficial for the immune system. 

Evidence suggests that probiotic bacteria, particularly some lactobacilli and bifidobacteria, have the potential to modify the microbiota, modulate the immune response and protect against infections (including of the respiratory tract). Varieties of plant-based foods, fiber and fermented foods help in creating and maintaining healthy gut microbiota and thus supporting the immune system. Interestingly, no published nutrition studies exist in the context of SARS-CoV-2 or COVID-19, but the Chinese researchers report dysbiosis in patients with severe COVID-19 and thus recommend treatment with probiotics. But its success in improving clinical outcomes remains unclear. 

Acute respiratory distress syndrome (ARDS), caused by severe infection of the respiratory epithelium that features excessive and damaging host inflammation is termed a cytokine storm. This is evident in the severe cases of COVID-19. There exists evidence from ARDS in other settings that the cytokine storm is benefitted and controlled by consuming omega-3 fatty acids. This action may be due to their metabolism to specialised pro-resolving mediators. However, this therapeutic approach still warrants investigation in severe COVID-19.

Source-

Calder PC. Nutrition, immunity and COVID-19. BMJ Nutrition, Prevention & Health 2020;3:doi: 10.1136/bmjnph-2020-000085