In recent years, some studies have shown that having regular Vitamin C intake (about 90mg daily) can help prevent people from getting the common cold, and having healthy Vitamin D levels (at least 400iu daily) can help in the event that you do get sick, by lowering the length and severity of viral infections people experience.
Vitamin C is found in most fruits, and Vitamin D can be found in fish, eggs, and your body can naturally produce it from being out in the sunlight every day.
By adding in just a couple servings of fruits, vegetables, healthy meats, and a few minutes of sunlight every day, you can help protect your body against sickness and stay healthy for the future.