Good is an adjective that describes a positive quality, state, or situation. For example, good health is a positive quality. An excellent teacher is someone with a high quality and quantity of health. Omega-3 fatty acids are good for the heart, and they may reduce the risk of heart attacks and strokes. Fiber, meanwhile, lowers cholesterol and makes us feel full. Some foods also contain plant sterols, which can lower cholesterol. These compounds are added to foods such as margarine and orange juice, but they also occur naturally in nuts.