Research shows that what you eat can be one of the most important factors to living a long, healthy life. Along with exercise, your diet can be extremely effective at preventing chronic disease and promoting health and longevity. Eating a significant portion of these 6 nutrient-dense foods every day can help you naturally strengthen your immune system and could add years to your life by boosting your health. GREEN VEGETABLES . Raw, leafy greens are packed with nutrients but are super low in calories. At only about 100 calories per pound, leafy greens are an excellent weight-loss food, since they can be eaten in virtually unlimited amounts. Greens provide protection for blood vessels, promote good eyesight, and are associated with lowering the risk for diabetes. Several of these vegetables, among them arugula, bok choy, kale, and collard greens, belong to the cruciferous family, a particular type of vegetable known for its cancer-fighting...