If you grew up in a home with a smoker, eat two apples a day. A study of 35,000 people by the National Institutes of Health found that it reduces lung irritation and helps prevent respiratory problems caused by secondhand smoke in childhood. So why do apples help protect and repair the lungs? Fruit-based fiber. So, a cup of raw blackberries or raspberries could get the same results. Or an apple and a pear. It turns out, the fiber in fruit benefits the lungs by reducing inflammation, and improving the body’s ability to process antioxidants.