Cassava is a calorie-rich vegetable that contains plenty of carbohydrates and key vitamins and minerals.Cassava is a good source of vitamin C, thiamine, riboflavin, and niacin. The leaves, which are also edible if a person cooks them or dries them in the sun, can contain up to 25% protein.Cassava is a source of resistant starch, which scientists suggest can boost a personâs gut health by helping nurture beneficial gut bacteria. Resistant starches remain relatively unchanged as they pass through the digestive tract.