Worldwide, the turmoil of the SARS-CoV-2 (COVID-19) pandemic has generated a burst of research efforts in search of effective prevention and treatment modalities. Current recommendations on natural supplements arise from mostly anecdotal evidence in other viral infections and expert opinion, and many clinical trials are ongoing. Here the authors review the evidence and rationale for the use of natural supplements for prevention and treatment of COVID-19, including those with potential benefit and those with potential harms. Specifically, the authors review probiotics, dietary patterns, micronutrients, antioxidants, polyphenols, melatonin, and cannabinoids. Authors critically evaluated and summarized the biomedical literature published in peer-reviewed journals, preprint servers, and current guidelines recommended by expert scientific governing bodies. Ongoing and future trials registered on clinicaltrials.gov were also recorded, appraised, and considered in conjunction with the literature findings. In light of the controversial issues surrounding the manufacturing and marketing of natural supplements and limited scientific evidence available, the authors assessed the available data and present this review to equip clinicians with the necessary information regarding the evidence for and potential harms of usage to promote open discussions with patients who are considering dietary supplements to prevent and treat COVID-19.

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Previous studies have suggested that right ventricular systolic pressure can be predicted from noninvasive estimates of the interval between pulmonary valve closure and tricuspid valve opening. To determine the basis for this relation, phonocardiograms and high fidelity right atrial and ventricular pressures were recorded in 29 patients with a right ventricular systolic pressure ranging from 20 to 149 mm Hg. In 22 patients with normal right atrial pressure (less than or equal to 8 mm Hg), both the time interval and the magnitude of pressure decrease from pulmonary valve closure to tricuspid valve opening were linearly related to systolic pressure (r = 0.89 and 0.96, respectively). Early pulmonary valve closure (decreased "hang-out" time) contributed to the greater magnitude of isovolumic pressure decrease at high systolic pressures, but correction for hang-out time did not eliminate the relation between systolic pressure and the pulmonary valve closure-tricuspid valve opening interval (n = 10). When patients with documented right coronary artery disease were excluded, the time constant for isovolumic pressure decrease also increased as a function of systolic pressure (r = 0.67, p less than 0.01, n = 24), suggesting impaired relaxation at high systolic pressures. However, the mean rate of pressure decrease (mean negative dP/dt) still was greater in patients with a high pressure because of the exponential nature of the isovolumic pressure-time relation.(ABSTRACT TRUNCATED AT 250 WORDS)