As millions of Americans are currently practicing social distancing and working and studying from home, the idea of proactively strengthening your immune system often gets lost in the noise.

What recent studies have shown is that we should be focusing on consuming more vitamin D, a key nutrient for building up your immune system. Vitamin D might be best known for strengthening bones, but it can also help prevent respiratory infections or reduce the severity of them, which can be considered heartening news for people who are worried about being infected by COVID-19.

One of the chief functions of vitamin D is to help activate T cells in the body. T cells are there to detect and destroy foreign pathogens like viruses, keeping your body in tip-top shape by maintaining a robust immune system.

The recommended amount of vitamin D for adults is between 600 and 800 IU, although this can vary, and you can get it through supplements, food and direct sun exposure. Even so, medical experts have said that about 1 billion people worldwide have insufficient levels of vitamin D, which have been linked to osteoporosis, muscle weakness, cancer and depression.

Some major food sources with high levels of vitamin D are egg yolks, cheese, beef liver and fatty fish. Keep in mind that cereals and dairy and plant milks have vitamin D added to them. Despite all of these choices, experts say it is still difficult to get your recommended daily allowance of vitamin D only through food.

In an article published in the Irish Medical Journal​, one research team revealed that 47 percent of all adults over 85 are deficient in vitamin D in the winter, putting this group at extremely high risk of mortality if they are infected by COVID-19. The report also found that only 4 percent of men and 15 percent of women take a vitamin D supplement.

Medical reference: The National Interest