New York, Supplements containing vitamins C and D and other micronutrients are a safe, effective and low-cost means of helping your immune system fight off COVID-19 and other acute respiratory tract diseases, say researchers.

According to the study, published in the journal Nutrients, public health officials should issue a clear set of nutritional recommendations to complement messages about the role of handwashing and vaccinations in preventing the spread of infections.

"There's a wealth of data that shows the role that good nutrition plays in supporting the immune system. As a society, we need to be doing a better job of getting that message across along with the other important, more common messages," said study researcher Adrian Gombart from Oregon State University in the US.

Specific vitamins, minerals and fatty acids have key jobs to play in helping your immune system, Gombart said. In particular vitamin C, vitamin D, zinc, and an omega-3 fatty acid found in fish, docosahexaenoic acid, also known as DHA, are critical for immune function.

The roles that vitamins C and D play in immunity are particularly well known.

According to the researchers, vitamin C has roles in several aspects of immunity, including the growth and function of immune cells and antibody production.

"Vitamin D receptors on immune cells also affect their function. This means that vitamin D profoundly influences your response to infections," Gombart said.

"The problem is that people simply aren't eating enough of these nutrients. This could destroy your resistance to infections. Consequently, we will see an increase in disease and all of the extra burdens that go along with that increase," he added.

That's why the researchers are urging not only a daily multivitamin, but doses of 200 milligrams or more of vitamin C (higher than the suggested federal guidelines of 75 milligrams for men and 50 for women) and 2,000 international units of vitamin D, rather than the 400 to 800 recommended depending on age.

There is no doubt that vaccines, when available, can be effective, but they're not foolproof, Athe researchers noted.The other collaborators of the study were the University of Southampton (United Kingdom), the University of Otago (New Zealand) and University Medical Center (The Netherlands).