Spinach contains large amounts of minerals and vitamins, especially vitamin A, calcium, phosphorus, iron and potassium. Spinach also has high levels of protein. Ninety-one percent of spinach weight is water. A serving of spinach contains 3.2 grams of protein, 4.3 grams of carbohydrates, and 0.3 grams of fat. It also contains Vitamin A, and C, thiamin, riboflavin, and niacin. Calcium, phosphorus, iron, sodium, and potassium are also found in spinach greens.