Which vitamin's intake, when below the RDA, can lead to physical performance impairment?

Iron plays a crucial role in various physiological processes, particularly in oxygen transport and energy metabolism, making it vital for optimal physical performance. When iron intake falls below the recommended dietary allowance (RDA), individuals, especially athletes, may experience diminished aerobic capacity, increased fatigue, and overall reduced performance levels. This is because iron is a key component of hemoglobin, which carries oxygen in the blood. Insufficient iron can lead to anemia, characterized by low hemoglobin levels and deterioration in endurance and strength.

Furthermore, athletes and individuals who engage in intense physical activities frequently have higher iron requirements due to increased losses from sweat, gastrointestinal bleeding, and the breakdown of red blood cells. Maintaining adequate iron levels is essential not only for the prevention of performance impairments but also for supporting overall health, immune function, and recovery.

While vitamin C, vitamin D, and vitamin B12 are important for various functions in the body, deficiencies in these nutrients do not typically lead to immediate physical performance impairments in the same direct way that iron deficiency does. Thus, the significance of iron in relation to physical performance is well-established, particularly for those with high activity levels, making it the correct choice in this scenario.