Parsnips are very nutritious so they are a great a addition to a healthy diet. The nutrition information for one cup of sliced parsnips is roughly 100 calories, 24 grams carbohydrates, 7 grams of fiber and 6 grams of sugar. They are an excellent source of potassium, Vitamins C and K and folate. They are also a good source of Vitamins B6, E and riboflavin, and minerals such as manganese, magnesium and phosphorus. If you're following a low carb diet, be sure to talk to your doctor to determine if parsnips are right for you.