Spinach may not give you superhuman strength to fight off villains like Popeye's nemesis Bluto, but this leafy green and other foods containing iron can help you fight a different type of enemy -- iron-deficiency anemia.

Iron-deficiency anemia, the most common form of anemia, is a decrease in the number of red blood cells caused by too little iron. Without sufficient iron, your body can't produce enough hemoglobin, a substance in red blood cells that makes it possible for them to carry oxygen to the body's tissues. As a result, you may feel weak, tired, and irritable.

About 20% of women, 50% of pregnant women, and 3% of men do not have enough iron in their body. The solution, in many cases, is to consume more foods high in iron.