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Microbes & Immunity Carotene and immunity to COVID-19 vaccine

the ability of vaccines to expose the immune system to abnormal cells. A well-balanced diet is widely recognized
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antigens and activate targeted immune responses, there was as crucial for optimal cellular functioning, including those
an urgent need to roll out vaccination programs to reduce in the immune system. When the immune system is
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the morbidity and mortality associated with COVID-19. activated during an infection, it requires abundant energy
Therefore, mass vaccination against SARS-CoV-2 has been for clonal expansion and the production of new proteins
widely implemented to curb the spread of the disease. and structures. Therefore, optimal nutrition is essential for
immune cells to respond to pathogens rapidly and effectively.
Vaccination offers substantial protection by generating
immunological memory against the virus, enabling Micronutrients, such as vitamins and trace elements, are
the rapid production of neutralizing antibodies upon essential to support both the innate and adaptive immune
systems. Research suggests that deficiencies or low levels
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subsequent exposure. Among the COVID-19 vaccines, of these micronutrients can weaken immune function and
the mRNA platform has garnered significant attention as reduce resistance to infections. 11
it represents the first widespread application of mRNA
vaccination in humans. Despite this advancement, the Nutritional interventions have potent effects on the
seemingly traditional inactivated virus vaccines continue to activation of host immune systems. Carotenoid supplements
be administered due to factors including public hesitancy are nutritional interventions that exhibit diverse
toward mRNA vaccines and the logistical challenges bioactivities, including antioxidant, anti-inflammatory,
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posed by the stringent storage and delivery requirements. and anticancer properties. The main carotenoids in crude
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However, inactivated virus vaccines have generally palm oil are α- and β-carotenes, which comprise 41.3%
demonstrated lower efficacy against COVID-19 than their and 41.0% of the total carotenoids in commercial red palm
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mRNA counterparts. Two to three doses of inactivated oil, respectively. Carotenes are fat-soluble Vitamin A pre-
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COVID-19 vaccines were reported to provide 90.15% cursors metabolized in the gut or liver to produce retinol,
protection against severe and critical COVID-19 cases, commonly known as Vitamin A. Vitamin A deficiency is the
even in the most vulnerable elderly population (≥60 years most common micronutrient deficiency globally, especially
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old). However, the immune response specific to SARS- in developing countries with low meat and protein intake.
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CoV-2 elicited by two doses of CoronaVac, an inactivated In addition, Vitamin A deficiency in infants and children
virus vaccine, was reported to wane significantly after has been associated with reduced immune response and
6 months. Consequently, a booster or third dose of the is a risk factor for several diseases, particularly vision
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vaccine was highly recommended. Hence, there is a need impairment. Besides animal products, Vitamin A can
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to improve and maintain the immune response to the be obtained from Vitamin A pre-cursors, such as α- and
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vaccine. Various factors affect the normal functioning of β-carotenes. Carotenoids have been reported to have
the immune system, including nutrition, lifestyle habits, immunomodulatory effects by increasing the activity
stress levels, and sleep quality. of natural killer (NK) cells and plasma interferon-
gamma (IFN-γ) levels in a xenograft model of human
The immune system comprises a repertoire of cells, breast cancer. In this model, carotene supplementation
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tissues, and molecules that work together to mediate upregulated anti-inflammatory markers (interleukin 4
resistance against infections. It is well established that B [IL-4] and IL-13) while downregulating pro-inflammatory
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cells, cluster of differentiation 4-positive (CD4 ) regulatory markers (IL-β, IL-6, and tumor necrosis factor-α) in nude
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T (Treg) cells, and CD8 cytotoxic T lymphocytes (CTLs) mice. In addition, carotene supplementation enhanced the
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are the three essential components of the adaptive immune production of peripheral blood NK cells and B cells, thus
system responsible for controlling SARS-CoV-2 infection. supporting the immunomodulatory effects of carotenes.
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Clinical trials reported that inactivated SARS-CoV-2 Numerous cellular models concluded that β-carotene
vaccination activates both innate and adaptive immunity, and its metabolites display antioxidant activity through
resulting in the upregulation of immune cells, such as the inhibition of reactive nitrogen (ONOO ) and oxygen
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CD16 monocytes, CD4 Treg cells, and CD8 CTLs, species (H O ), respectively, reducing lipid peroxidation
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along with increased levels of neutralizing antibodies. B activity. In addition, Vitamin A supplementation in
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cells play a pivotal role in antibody-mediated (humoral) porcine circovirus type 2-vaccinated pre-pubertal gilts has
immunity. Upon activation, the activated antigen-specific been reported to significantly increase circovirus antibody
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B cells differentiate into plasma cells, which produce titers compared to the control group. Although numerous
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antigen-specific antibodies, and memory B cells, which studies have demonstrated the immunomodulatory
enable a swift response upon reinfection. The T-helper potential of Vitamin A and its pre-cursors as dietary
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(Th) cells secrete cytokines that can regulate B cell supplements, their mechanism of action remains poorly
activation and CTLs, while the CTLs kill virus-infected or understood.
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Volume 2 Issue 3 (2025) 73 doi: 10.36922/MI025110021