This review summarizes the scientific knowledge concerning the impact of vitamins, magnesium, and trace elements on various mechanisms contributing to the possible treatment and prevention of COVID-19, including its delayed consequences. A search was conducted in various databases, including PubMed, Scopus, ClinicalTrials.- gov, and Web of Science. Among the main mechanisms involved in the effects of the studied micronutrients, immune-boosting, antioxidant and anti-inflammatory effects were also highlighted. The analyzed clinical trials confirmed that supplementation with higher daily doses of some micronutrients can reduce SARS-CoV-2 viral load and hospitalization time. The potential role of most known vitamins in preventing, treating COVID-19, and rehabilitating patients was considered. The most promising agents for combating COVID-19 and its consequences might be the following vitamins: vitamin D, ascorbic acid, polyunsaturated fatty acids (PUFAs), and some B complex vitamins. Inorganic elements deserving attention include magnesium and trace elements, such as zinc, selenium, copper, and iron. Some associations were found between micronutrient deficiencies and COVID-19 severity in children, adults, and older people. Patients can obtain the aforementioned micronutrients from natural food sources or as supplements/- drugs in various dosage forms. The reviewed micronutrients might be considered adjunctive treatment strategies for COVID-19 patients.

Polyphenols (PPs) are a large group of phytochemicals containing phenolic rings with two or more hydroxyl groups. They possess powerful antioxidant properties, multiple therapeutic effects, and possible health benefits in vivo and in vitro, as well as reported clinical studies. Considering their free-radical scavenging and anti-inflammatory properties, these substances can be used to treat different kinds of conditions associated with metabolic disorders. Many symptoms of metabolic syndrome (MtS), including obesity, dyslipidemia, atherosclerosis, elevated blood sugar, accelerating aging, liver intoxication, hypertension, as well as cancer and neurodegenerative disorders, are substantially relieved by dietary PPs. The present study explores the bioprotective properties and associated underlying mechanisms of PPs. A detailed understanding of these natural compounds will open up new opportunities for producing unique natural PP-rich dietary and medicinal plans, ultimately affirming their health benefits.

Aging is characterized by an imbalance between damage inflicted by reactive oxygen species (ROS) and the antioxidative defenses of the organism. As a significant nutritional factor, the trace element selenium (Se) may remodel gradual and spontaneous physiological changes caused by oxidative stress, potentially leading to disease prevention and healthy aging. Se is involved in improving antioxidant defense, immune functions, and metabolic homeostasis. An inadequate Se status may reduce human life expectancy by accelerating the aging process or increasing vulnerability to various disorders, including immunity dysfunction, and cancer risk. This review highlights the available studies on the effective role of Se in aging mechanisms and shows the potential clinical implications related to its consumption. The main sources of organic Se and the advantages of its nanoformulations were also discussed.