Scientist found that daily consumption of 10g dark chocolate (minimally 70% cacao) significantly increased heart rate variability (HRV). (1) This effect of dark chocolate may indicate that it can decrease the cytokine storm induced by COVID-19 infection. The fatal consequences of COVID-19 are prognostized by the persistent elevation of the cytokine Il-6. (2) HRV is inversely correlated with inflammatory cytokines and particularly with Il-6. (3)
Harvard scientist discovered that areas polluted with particulate matter have up to 20 times higher mortality rates than areas with low air polution. (4)
Particulate matter air polution decreases HRV and severely impairs brain functions. (5) (6)
Air pollution harms vagus nerve functions and so damages the vagus nerve dependent cholinergic anti inflammatory pathway and so the ability of it to prevent cytokine storm and may cause arrythmia. (7)
The central regulation of vagus nerve of mice exposed to prolonged air polution is impaired and the inflammatory markers of these animals are elevated, however chocolate administration mitigates the inflammatory damages. (8)

It is imprortant to note that the risk groups of COVID-19 infection with the most severe symptoms have low HRV, they are aged and/or have cardiovascular problems, hypertension, diabetes, COPD and are smokers. The support of the cholinergic anti inflammatory pathway by inceasing HRV may be a life saving intervention. Dark chocolate administration beside central proinsulin C-peptide may be an easy way to support damaged vagus nerve functions and incease HRV. (9) (10)

1. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-52732016000600765
2. https://www.sciencedirect.com/science/article/pii/S1568997220300926
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4476948/
4. https://www.medrxiv.org/content/10.1101/2020.04.05.20054502v1.full.pdf
5. https://www.frontiersin.org/articles/10.3389/fenvs.2018.00002/full
6. https://pubmed.ncbi.nlm.nih.gov/31746986/
7. https://particleandfibretoxicology.biomedcentral.com/articles/10.1186/s12989-017-0196-2
8. https://pubmed.ncbi.nlm.nih.gov/21030725/
9. https://pubmed.ncbi.nlm.nih.gov/8781764/
10. https://pubmed.ncbi.nlm.nih.gov/11151760/