3. Squash

There are no too many foods that would contain as many various nutrients as Butternut squash. This is a great source of calcium, potassium, copper, iron. It provides the body with zinc, manganese and magnesium. You can strengthen your immune system if you include squash in your menu. Do not throw away the seed and turn them into a snack by adding a bit of olive oil and baking the seeds until they start to pop.