The term SPINACH NUTRIENT can be solved by the four-letter word IRON. IRON is an essential mineral that is found in many foods, including spinach. It is important for a variety of bodily functions, such as transporting oxygen throughout the body and helping to form red blood cells. Spinach is a particularly good source of IRON, providing up to 6.4 milligrams per cup. Eating a diet rich in IRON can help prevent anemia and other health problems.