Iron is a fundamental element for the adequate supply of oxygen to tissues – essential for energy production routes at the cellular level – as well as an essential component for the storage and transport of proteins such as hemoglobin, myoglobin or cytochromes (Buratti et al., 2014).
This micronutrient can be found in food in two ways: heme iron (from animal sources) and non-heme iron (from other sources such as vegetables). The absorption of heme iron is more efficient, since non-heme iron can be affected, for example, by the presence of phytates and polyphenols, which are very present in foods of plant origin. However, heme iron only makes up about 10% of all the iron ingested in the diet.
Despite its biological importance, iron deficiency is a problem widely described in athletes, with a prevalence that varies between 26-31% in women and between 3-11% in men (Malczewska et al., 2001; Parks et al. ., 2017). The figures are higher in women due mainly to a higher demand for iron during menstruation and pregnancy (McClung et al., 2014). Different studies have shown lower levels of iron in the body in women athletes compared to inactive women (Spodaryk et al., 1996, Woolf et al., 2009), even though athletes ingest higher amounts of iron in the diet (Woolf et al., 2009), highlighting a possible negative effect of the exercise on the micronutrient status. Other risk factors could be an insufficient intake of iron in the diet (possibly as a result of inadequate energy intake in general); vegetarian diets, as discussed above; the post-exercise increase in interleukin-6 levels (McClung et al., 2014), which in turn will activate the expression of the hormone hepcidin, produced by the liver and with a key role in the metabolism of iron, reducing its absorption (Díaz et al., 2015).
Among the main symptoms of iron deficiency we can highlight fatigue, lack of concentration, negative mood, drowsiness and, in severe cases, iron deficiency anemia, all of them negatively affecting sports performance and quality of life.
Iron is essential for oxidative metabolism and, therefore, it is especially important for endurance athletes whose performance depends on high cardiorespiratory fitness. However, it is precisely in these where iron deficiency seems to be more prevalent (Hinton, 2014, Sim et al., 2019). The reasons for this are an increase in the metabolism and turnover of iron and the destruction of red blood cells by the tread, sweat and small gastrointestinal hemorrhages that usually occur in long distance competitions. Therefore, it is recommended that long distance runners increase iron consumption by 70%, that is to say, above the 14.8 mg / day established as a Daily Amount Recommended by the British Nutrition Foundation (Whiting and Barabash, 2006). This recommendation is especially valuable for premenopausal women with heavy menstrual bleeding.
Therefore, the prevention of iron deficiency becomes essential in order to obtain the highest possible performance, either during training or on the day of competition. In this sense, the modification of the diet is considered the main strategy for the prevention of iron deficit in women athletes (Alaunyte et al., 2015). In the case of athletes who can not get all the iron required through the diet, they can resort to nutritional supplements. Thus, as demonstrated in a study carried out by Dr. Fernando Naclerio and his research group, ingesting a beef protein drink can be an effective strategy to improve iron metabolism, since it prevents the depletion of its reserves in endurance athletes during the training periods (Naclerio et al., 2017).
In short, we observe how nutrition is a differential factor associated with performance. Success or failure in a competition may be due to inadequate nutritional intake. The control of iron levels, especially in endurance athletes, and especially in women, has become one of the main workhorses for doctors and trainers, since they combine several factors (training, iron intake often inadequate, menstrual period, …) that can lead to an iron deficiency or, more seriously, to a ferropenic anemia. Therefore, mainly women athletes should incorporate strategies focused on dietary modification, with a particular focus on the intake of iron, especially iron heme, and the consumption of supplements, such as beef protein (100% All Beef), which can enhance their metabolism.
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Javier S. Morales
Docente e Investigador en la Universidad Europea de Madrid.