Training

Iron Can Make the Difference

Iron supports oxygen transport and energy production; athletes, especially endurance athletes and women, face a higher risk of deficiency.

Date 09.08.2019

Author

maq

Topics

Iron is fundamental to an adequate oxygen supply to tissues—essential for cellular energy-production pathways—and is an indispensable component of oxygen-storing and transporting proteins such as hemoglobin, myoglobin and cytochromes (Buratti et al., 2014).

This micronutrient occurs in food in two forms: heme iron from animal sources and non-heme iron from sources such as plants. Heme iron is absorbed more efficiently, because non-heme absorption can be affected by phytates and polyphenols, which are abundant in plant foods. Heme iron nevertheless accounts for only around 10% of all dietary iron.

Despite its biological importance, iron deficiency is widely reported in athletes, with a prevalence of 26–31% in women and 3–11% in men (Malczewska et al., 2001; Parks et al., 2017). Rates are higher among women, mainly because iron demand rises during menstruation and pregnancy (McClung et al., 2014). Studies have shown lower body-iron levels in female athletes than in inactive women (Spodaryk et al., 1996; Woolf et al., 2009), even when athletes consumed more dietary iron (Woolf et al., 2009), suggesting a possible negative effect of exercise on micronutrient status. Other risk factors include insufficient dietary iron, possibly because of generally inadequate energy intake; vegetarian diets, as discussed above; and post-exercise increases in interleukin-6 (McClung et al., 2014), which activate expression of the liver-produced hormone hepcidin. Hepcidin has a key role in iron metabolism and reduces absorption (Díaz et al., 2015).

Major symptoms of iron deficiency include fatigue, poor concentration, negative mood and drowsiness and, in severe cases, iron-deficiency anemia. All negatively affect sports performance and quality of life.

Iron is essential to oxidative metabolism and is therefore especially important for endurance athletes, whose performance depends on high cardiorespiratory capacity. Iron deficiency nevertheless appears most prevalent in this population (Hinton, 2014; Sim et al., 2019). Reasons include increased iron metabolism and turnover, along with red-blood-cell destruction caused by foot strike, sweating and small gastrointestinal bleeds that commonly occur in long-distance competition. Female long-distance runners are therefore advised to increase iron intake by 70%, above the 14,8 mg/day recommended daily amount established by the British Nutrition Foundation (Whiting and Barabash, 2006). This recommendation is particularly valuable for premenopausal women with heavy menstrual bleeding.

Preventing iron deficiency is essential for achieving the best possible performance in training and competition. Dietary modification is considered the primary prevention strategy for female athletes (Alaunyte et al., 2015). Athletes unable to obtain all required iron from diet can use nutritional supplements. A study by Dr. Fernando Naclerio and his research group showed that consuming a beef-protein drink can effectively improve iron metabolism by preventing depletion of iron stores in endurance athletes during training periods (Naclerio et al., 2017).

CONCLUSIONS

Nutrition can clearly be a differentiating factor in performance, and success or failure in competition may result from inadequate intake. Monitoring iron levels, especially in endurance athletes and women, is a major challenge for doctors and coaches because several factors—training, frequently inadequate iron intake and menstruation—can combine to cause iron deficiency or, more seriously, iron-deficiency anemia. Female athletes in particular should adopt diet-modification strategies focused on iron intake, especially heme iron, and consider supplements such as beef protein that may support iron metabolism.

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REFERENCES:

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