Supplements that contain higher than federally recommended levels of vitamins C and D may be a safe, effective, and low-cost way of helping your immune system fight coronavirus disease 2019 (COVID-19), according to a study published in Nutrients.

The COVID-19 pandemic has caused more than 800,000 deaths with over 23.3 million cases reported worldwide, according to the World Health Organization. Acute respiratory tract infections kill more than 2.5 million people every year, according to the study.

Vitamins C and D, zinc, and omega-3 fatty acids are critical for immune function. Not eating enough of these essential nutrients can affect resistance to infection, increase disease severity, and burdens associated with the disease.

Researchers from Oregon State University (OSU) are urging the use of a daily multivitamin, but also vitamin C and vitamin D supplements much higher than federally recommended guidelines. The study authors recommended 200 milligrams or more of vitamin C and 2000 international units of vitamin D.