The phrase "plenty of dietary fiber" refers to consuming a large amount or an adequate quantity of dietary fiber in one's daily food intake. Dietary fiber is essential for maintaining good health, as it promotes proper digestion and helps regulate bowel movements. It also plays a role in reducing the risk of certain diseases such as heart disease, diabetes, and obesity. Therefore, when someone says they have "plenty of dietary fiber," it means that their diet contains an adequate amount of this important nutrient.