Mild iron deficiency may affect female endurance and behavior.

The function of central nervous system (CNS) processes is highly dependent on iron containing enzymes and proteins. Therefore, even mild iron deficiency (ID) may result in decreased endurance, increased irritability and withdrawal behavior among women. The current study was designed to assess the effects of iron status on perceived energy level along with its electroencephalographical (EEG) correlates and cognitive capacity of young women, since this group is at particular risk of experiencing depleted iron stores and iron deficiency anemia. The study group consisted of 23 non-anemic women of reproductive age (20-32 years) during their follicular phase of menstrual cycle. All participants were moderately physically active with a mean weekly energy expenditure of 1110 ± 450 Metabolic Equivalent of Task per minute-(MET/min). The group's electroencephalographic (EEG) alpha asymmetry and psychometric data - intelligence, anxiety level and temperamental traits (activity, briskness, sensory sensitivity, emotional reactivity, perseveration and endurance) were assessed and compared between iron deficient (serum ferritin <12 μg/l) and iron sufficient (serum ferritin ≥12 μg/l) females. Participants with depleted iron stores reported lower levels of activity (p = .004; partial η = 0.34) and endurance (p = .038, partial η = 0.25), temperamental traits, and presented increased relative left EEG alpha activity in prefrontal regions (p = .004; partial η = 0.63), which is a characteristic EEG pattern for withdrawal tendencies. Iron-depleted females did not differ in anxiety and general intelligence scores from those which were iron sufficient, however needed more time (median difference: 3 min, p = .004; partial η = 0.53) to complete an administered intelligence test, which may reflect lowered endurance during a cognitive-demanding task. These data provide proof that that even mild iron deficiency may be connected with CNS function and lead to decreased endurance, or at least cognitive endurance, which may be a risk-factor for mood disorders. Therefore, more attention should be paid to preventing even mild iron deficiency, particularly among young women.