Iron

USE: Iron is a metal that is essential for life. It is a part of proteins and enzymes found throughout your body (including hemoglobin and myoglobin), and is critical for Hemoglobin formation in red blood cells, and carrying oxygen around the body for energy utilisation.  Iron is an important component of your muscles, and it helps regulate the growth of cells. It comes from foods you eat and any excess iron is stored for future use. Vitamin C aids the absorption of iron in the body significantly. Next time you eat Spinach, squeeze lemon juice on it (the Vitamin C in the lemon will amplify the absorption of the iron in the spinach).  
SOURCE: Great sources are meat, fish, poultry, eggs, legumes, dark green vegetables like spinach and broccoli, dried fruits and fortified cereals. While you can get iron from animal and plant sources, the body absorbs iron far more readily from animal sources.