Calcium, iron, and zinc perform especially important functions for athletes. The latest calcium recommendations are based on levels of intake to promote calcium retention, maximize bone mineral density, and inhibit bone loss. Increased risk of stress fracture among athletes is associated with lower calcium intake and lower bone density compared to control athletes. Dairy products, fish with bones, broccoli, and fortified cereals and juices are good calcium sources. Iron affects oxygen transport and aerobic metabolism as a component of hemoglobin, myoglobin, and oxidative enzymes.
Immune function is dependent on iron-containing enzymes.
Consuming adequate amounts of iron is essential for optimal aerobic endurance performance. Iron depletion is the first stage of iron deficiency and the most common type of iron deficiency among athletes. Lean red meats, dark poultry, fortified cereals, whole grains, and legumes are good iron sources. Zinc is essential for protein synthesis, it aids in healing and immune function, and is present in antioxidant enzymes and enzymes involved in energy metabolism. Zinc is found in meat, poultry, seafood, and whole grains.