Vitamin D is critical for bone and muscle health and is known to be effective in fighting depression. Deficiency in this Vitamin compromising the immune system is pretty much settled science. Known as the "sunshine vitamin," it's naturally produced by the skin when exposed to sunlight, but can also be absorbed through vitamin-D-rich foods, such as salmon and whole eggs, as well as supplements.
Researchers at Northwestern University analyzed hospital data from countries infected with Covid-19 including China, Iran, Italy, South Korea, Spain, Switzerland, UK and the USA and concluded that high death rate countries, including Italy and Spain, were more likely to have patients with Vitamin D deficiencies. Even scholars at Johns Hopkins agree Vitamin D deficiency is underdiagnosed and that it may reduce complications and help prevent death in those who are infected with Covid-19. On a more basic level our research indicates that while Vitamin D may not make us "happy" it can have a significant effect on our Mood. For most people "the proper amount of sunlight" is the best Vitamin D solution. Tom LeDuc