Dr. Simin Meidani, leader of the nutritional immunology team at Tufts University in America, said: Vitamins C, D, B and zinc help in strengthening the immune system.

The immune system is the first line of defense that sends antibodies to fight diseases, and the younger the body and the healthier the body, the better the immunity is.

"Meidani" explained to the American "CNN" website that the best way to strengthen immunity is to eat a large variety of fresh fruits and vegetables every day, with some high-quality whole grains, a few lean proteins and a few healthy oils.

And she said: During the winter season, and in case you want to increase the effect of food on the immune system; The body needs to increase the amount of fruits and vegetables every day.

Diets rich in fruits and vegetables have been linked to a reduced risk of heart attacks, strokes, cancer and early death.

In the United States, current dietary guidelines recommend eating up to two cups of fruit and two to three servings of vegetables per day.