Although buckwheat is not a grain, it is sometimes referred to as a pseudocereal. For processing into food, buckwheat seeds must first be dehulled. The remaining seed material, called groats, can be ground into flour. Roasted groats are known as kasha.
Buckwheat is high in protein and B vitamins and rich in phosphorus, potassium, iron, calcium, and lysine. A great source of dietary fiber, buckwheat helps lower cholesterol levels in the blood.
A one-cup serving of cooked buckwheat groats provides 17 grams of dietary fiber (68% of the daily requirement for a 2000 cal/day diet) and 22 g of protein. (About.com's Calorie Count site provides a complete nutritional analysis.)