COVID-19 is the major health concern in the world. In this unprecedented time of crisis, the preventive measures taken to combat COVID-19 pandemic is the improvement of nutritional pattern and lifestyle modifications. The severity of COVID‐19 infection varies widely and the manifestations varies widely from asymptomatic disease to severe acute respiratory tract infection. Fever, dry cough, chest tightness, myalgia, fatigue, loss of appetite, hearing and taste sensation dysfunction are the most prominent symptoms .
The COVID-19 epidemic primarily induces pro-inflammatory cytokines (e.g., IL-1 and IL- 6) and lung inflammation. This virus can also damage other vital organs of the host body through the expression of the angiotensin-converting enzyme 2 (ACE2) receptor .
Sufficient drop in immune cells such as natural killer (NK) cells, cytotoxic, regulatory, helper T cells, and macrophages/monocytes have been pointed out during COVID-19 infection. Organosulphur compounds in garlic mediate immune functions.
The beneficial effects of Allium sativum (garlic) on health have been reported for centuries. Garlic contains numerous phytochemical compounds that have the potential to regulate immunity and decreases the expression of proinflammatory cytokines and to reverse the immunological anomalies to more reasonable range .
Garlic does not cure the novel COVID-19 but has the potential to decrease the expression of pro-inflammatory cytokines and can boost the immune system too. Allicin is the main organosulfur compound in garlic that is involved in the suppression of pro-inflammatory cytokines and also modulate immune functions.
The presence of other sulfur-containing phytochemicals in garlic (Allium sativum) exhibits sufficient anti-oxidant, immunomodulatory, anti-inflammatory, antitumor, anti-hyperglycemic, anti-microbial, and cardio-protective properties.
In the case of COVID-19, entry of the virus (SARS-CoV-2) is facilitated by glycosylated spike (S) proteins, which cover the surface of the SARS-CoV-2 virus and attach to the host cell receptor. A protein type called serine protease located on the host cell membrane promotes the entry of the virus into the cell. Once the virus gets entry into the cell, the viral RNA is replicated and structural proteins are synthesized, assembled and packaged in the host cell, after which more new viral particles are released. Recent molecular screening suggests that allice, the main component in the garlic may inhibit the host’s protease activity and thus may prevent virus penetration and replication.
Organosulfur (e.g., allicin) and flavonoid (e.g., quercetin) compounds in the garlic may help in decreasing the viral replication of SARS-CoV-2 by interacting with serine proteases .
T cell-mediated immunity plays an important role in fighting against foreign antigen. Decreased numbers of regulatory T cells observed in COVID-19 infection. Regulatory T cells also exhibit anti-inflammatory properties.
The helper T cells (CD4 + T cells) and the cytotoxic T cells (CD8 + T cells) are two major types of T cells. Helper T cells ‘help’ other cells of the immune system, while cytotoxic T cells kill virally infected cells and tumours. Both are important soldiers of the immune system. Natural killer cells are a group of immune cells possessing cytolytic activity against virus-infected and tumor cells.
In patients with COVID-19 infection, reduction of these cells were noted.
Garlic supplementation causes significant increases in CD4 + and CD8 + cells. These cells help in boosting immune function.
Researchers showed that healthy lifestyle modifications and nutritional foods help in combating COVID-19.
Organo-sulfur and flavonoids constituents present in garlic are involved in immunomodulatory, antioxidant, and antimicrobial activities and may also be able to pre-and post-exposure prophylaxis by increasing the activity and number of cytokine suppressors, lymphocytes, natural killer cells, and macrophages. Therefore, garlic helps in decreasing the adverse impacts of antivirals by reducing the used dose and synergically improves the remedy and outcomes by decreasing the inflammation and respiratory symptoms.
Garlic and its phytochemicals are well known for prevention and treatment of cardiovascular diseases (CVD). Garlic intake has significant effects on lowering blood pressure, prevention of atherosclerosis, reduction of serum cholesterol and triglyceride, inhibition of platelet aggregation.
Sufficient garlic intake promotes antioxidant activities and reduces oxidative stress either by increasing the endogenous antioxidant synthesis or reducing the production of reactive oxygen species (ROS).
Garlic and its phytochemical derivatives have anti hyperglycemic effect. The main anti-hyperglycemic activity of garlic is attributed to sulfur containing compound allicin. It has also been reported to be effective in reducing insulin resistance .
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