Unless you live in a bubble, you are being exposed to sneezing, bacteria-covered doorknobs, and germ-infested work environments. The old phrase, “what you can’t see won’t hurt you”, isn’t necessarily true when it comes to viruses. Finish up this winter season sickness-free by taking good care of yourself. Washing your hands often is one line of defense. Another is loading up your diet with foods that will help fight off illness.

Here are the best nutrients for keeping your immune system strong:

Vitamin D, also known as the sunshine vitamin, helps regulate the immune system. According to a 2009 study published in the Archives of Internal Medicine, people with low levels of Vitamin D are more susceptible to catching colds. Eat regular food sources of vitamin D, including, salmon, fortified milk and yogurt, and eggs.