We all need iron, but many of us don’t get enough of it. The primary role of iron is to make haemoglobin, the molecule responsible for delivering oxygen to the tissues of the body including the muscles and the brain, so you don’t have to be a sports scientist to understand why it is so vital. Yet you may not be aware that many of our daily habits like drinking tea or coffee, exercising, and what we eat can all affect our ability to absorb iron.
With this in mind, we caught up with Professor Carlo Brugnara of Harvard Medical School, a world research leader in haematology (the study of the physiology of the blood), to discuss the importance of iron. Carlo is a scientific advisor to Orreco and has been publishing haematological studies for over 30 years. With him were Orreco scientists Dr Charlie Pedlar and Georgie Bruinvels.
Why do you feel iron is so important?
Carlo: “Iron is the fourth most abundant element in the earth’s crust, but only a few grams of this essential metal are present in the human body. Crucially for sport and critically for normal physiological function, oxygen transport depends on the iron-containing protein haemoglobin, and many other key biological processes depend on enzymes and proteins that contain iron.”
For Charlie Pedlar, the importance of iron for sport cannot be understated. “Without it we cannot produce haemoglobin and therefore aerobic power may be compromised. Interestingly we’ve seen iron deficiency at some point in every sport we’ve worked in. We know that where an athlete is truly iron deficient, giving them a supplement to normalise iron status has a dramatic effect on haemoglobin mass and therefore on exercise capacity [1]. On the other hand, if there is no iron deficiency, consuming extra iron has no effect beyond a placebo.”
Why may those who exercise have an increased likelihood of being iron deficient?
Carlo: “Competitive female athletes seem to have a greater risk of developing iron deficiency due to iron loss in menstrual flow, gastrointestinal bleeding, urinary loss due to red cell rupture (cells can be crushed or damaged in sport) and inadequate dietary iron intake. Male athletes can also develop iron deficiency, but it is far less common. Exercise training, particularly endurance training, causes a greater production of red blood cells packed with haemoglobin and that causes a greater need for iron.”
Picking up on Carlo’s reference to female athletes, Georgie Bruinvels adds that “Regardless of exercise, menstruating women are at an increased risk of iron deficiency compared to men. This risk is greater in those with heavy menstrual bleeding, which surprisingly is a significant issue amongst athletes at all levels, from recreational to elite. More than a third of both elite athletes and marathon runners have a history of heavy menstrual bleeding [2]. It is important to consider this when working with female athletes.”
Who is at an increased risk of iron deficiency?
Carlo: “Blood loss is an important cause of iron deficiency and menstruating women of a reproductive age are particularly susceptible to iron deficiency. Any other cause of chronic blood loss ultimately will produce iron deficiency. In developing countries, intestinal parasites (hookworm, whipworm) are also a major cause of iron deficiency. It is estimated that more than 1 billion people may carry these parasites and be at risk.
Iron deficiency is also quite common in toddlers and in the first years of life due to rapid growth and insufficient dietary intake. Cows-milk contributes to iron deficiency and therefore is not indicated in the first year of life. (But, of course, athletes should not abstain from drinking milk because of other important benefits such as calcium and Vitamin D.) Iron deficiency in infants and toddlers is associated with measurable reductions in cognitive capabilities, suggesting that iron is key for proper brain development. Pregnancy is another condition in which iron intake is often insufficient due to rapid growth.”
For Charlie, context is everything. “For example, heavy training leads to a greater iron turnover, as does going to altitude where erythropoiesis (the production of new red blood cells) is increased. Regular data points on athletes is highly recommended so that these phases of training can be evaluated against baseline data for each athlete. Reducing training load after a competition or descending from altitude allows iron status to be restored, having the same effect as supplementing with iron [3]. This is often overlooked.”
Are there any particular warning signs associated with iron deficiency?
Carlo: “Symptoms associated with anaemia (pallor, fatigue, weakness, raised heart rate) are the most common manifestation of iron deficiency. Less common, but quite indicative of iron deficiency, is pica, the compulsive consumption of non-nutritious substances like soil, ice, starch or clay. This is believed to be caused by lack of iron in the central nervous system. Athletes, however, would notice a loss in performance before getting to this stage.”
What are the best food sources of iron for both meat eaters and vegetarians?
Carlo: “The most readily absorbable form of iron is haem iron derived from animal meat, especially red meat. Poultry and seafood also contain reasonable amounts of heme iron. Legumes/vegetables such as beans, spinach and lentils are also good sources of iron. Rice, on the other hand, is a very poor source of iron. Vitamin C (ascorbic acid) promotes absorption of iron, and is recommended in conjunction with iron supplements.”
Is there any specific advice you would give people about timing iron intake and what other foods to eat or avoid?
Carlo: “Iron supplements are best taken on an empty stomach, away from meals to avoid interferences with iron absorption. Phenolic acids (tannins) present in tea, wine and some fruits reduce iron absorption. Polyphenols contained in coffee are also known to inhibit iron absorption. Bran and other wheat products contain phytates (organic polyphosphates),which bind to iron and reduce its absorption. Antacid therapy [like Gaviscon™ or TUMS™] increases gastric pH and reduces iron absorption.”
Professor Carlo Brugnara (pictured above in conversation with Georgie Bruinvels at the Orreco Science Summit, Ireland) is a world leader in haematology and iron. He is Director of the Hematology Laboratory in the Department of Laboratory Medicine at Boston Children’s Hospital, Professor of Pathology at Harvard Medical School, and Editor in Chief of the American Journal of Hematology.
