So… About Iron Again

Covering client concerns from nutrient sourcing to nutrient timing

From Fitness Trainer January/February

So… About Iron Again

So… About Iron Again

we know iron is a factor in oxygen transport success, but as fitness trainers do we know why? You can easily tell a winded client that they may want to consider iron supplementation. Telling them why, and how, a daily dose of Fe (iron) could impact their training results may be a bit harder. Fortunately, there has been extended efforts towards the scientific understanding and supplementation techniques for athletes during the past decade. Whether the athlete is anemic, iron deficient (ID) to begin, or is coming into a sport with normal Fe ranges – diagnosis, treatment and timing have new findings.


Iron is required for the production of red blood cells also known as haematopoiesis, but it’s also part of haemoglobin binding to the oxygen and thus facilitating its transport from the lungs via the arteries to all cells throughout the body. The body requires iron for the synthesis of its oxygen transport proteins, in particular hemoglobin and myoglobin, and for the formation of heme enzymes and other ironcontaining enzymes involved in electron transfer and oxidation-reductions. Almost two-thirds of the body’s iron is found in the hemoglobin present in circulating erythrocytes, 25% is contained in a readily mobilizable iron store, and the remaining 15% is bound to myoglobin in muscle tissue and in a variety of enzymes involved in the oxidative metabolism and many other cell functions. We see this statistic of 25% and realize that building up the iron stores has become a starting point for our bodies. Absorption from diet can vary but seems to be a lower percentage, though can vary person to person, compared to other sources.


The most recent key I have discovered, with research as current as 2014, is the hepcidin factor as the circulating peptide hormone secreted by the liver that plays a central role in the regulation of iron homeostasis. Hepcidin acts by binding to ferroportin, an iron transporter present on the cells of the intestinal duodenum and macrophages. Binding of hepcidin induces ferroportin internalization and degradation. It is important to understand that dietary iron comes in two forms, heme and non heme.

 Heme iron
  • from consumption of meat, poultry, and fish.
Nonheme iron
  • From consumption of cereals, legumes, fruits, and vegetables.


Decreased iron entry into plasma results in low transferrin saturation and less iron is delivered to the developing erythroblast. This directly affects oxygen transport and the efficiency of the red blood cells. Serum ferritin is a good indicator of body iron stores under most circumstances. When the concentration of serum ferritin is ≥15 μg/L iron stores are present; higher concentrations reflect the size of the iron store; when the concentration is low (<12 μg/L for <5 years of age and <15 μg/L for >5 years of age) iron stores are depleted. A simple blood test at your physician’s office can provide this information within a blood panel.


Major inhibitors of iron absorption are phytic acid, polyphenols, calcium, and peptides from partially digested proteins.

  • has been shown to have negative effects on non heme and heme iron absorption, which makes it different from other inhibitors that affect nonheme iron absorption only.
Vitamin C
  • The oxidation of ascorbic acid, or Vitamin C, also showed some inhibiting factors on a biochemical level exhibited in an article by Weissberger and Santhirapala.
  • Their point that iron-citrate complexes within mucosal lining cells (fluids within the body) enhance the oxidation process should be taken into consideration. This

suggested that changes be made to having the presence of Vitamin C and Iron together. In the past that was always advised, so it was interesting to read a different opinion on supplementation.

  • My inquiry would be though – what if the vitamin c was in a different form? That is to say, if you didn’t take the iron pills with orange juice would ascorbic acid

from vegetables still conflict? Their main points were that the two items together (Fe and Ascorbic Acid) cause gastrointestinal issues.


The amount of supplementation should be suggested by a doctor and stem from the patient/client’s test results from their blood test. Supplementation should

also be approached carefully as the liquid forms can be better absorbed by some and oral iron supplementation can be tolerated best by others. The decision is

to be decided between client and doctor or registered dietitian. If tests numbers do not improve with one method, options should be explored to others. Diet should be enhanced from all angles though. A registered dietitian should be referred to

plan for adequate amounts of iron and what foods are appropriate in what desired amounts.

Training and Timing

Training modalities and timing of supplementation are of utmost importance. Avoiding the peak periods of hepcidin, that are elevated post- exercise, increases the chances of optimal iron absorption. Hepcidin is always responding to maintain iron homeostasis, in one study they determined this can maintain up to three hours post exercise. There is a fine line and it varies between individuals when after exercise your optimal iron absorption can occur postexercise. Other international studies, more specifically, Auersperger – showed that iron stores could possibly not regain even ten days post exertive exercise. In my personal experience with working with dietitians, training, coaches, and other athletes – many times you are relying on trial and error. Each athlete or client will be different but taking into account the array of numbers that you can obtain from a blood serum ferritin panel will assist with the layout of that journey. You can also rely on those ranges as pinpoints of progress and a baseline. Combinations of timing and different methods of supplementation in conjunction with dietary additions/changes will improve iron absorption and exercise progress. If you do not see any changes after most combinations have been assessed, consider any underlying diseases the client or athlete may have and pursue counsel from a M.D.


  1. Abbaspour N, Hurrell R, Kelishadi R. Review on iron and its importance for human health. Journal of Research in Medical Sciences : The Official Journal of Isfahan University of Medical Sciences. 2014;19(2):164-174.
  1. Peeling P, Sim M, Badenhorst CE, Dawson B, Govus AD, et al. (2014) Iron Status and the Acute Post-Exercise Hepcidin Response in Athletes. PLOS ONE 9(3): e93002.
  2. Weissberger A, LuValle JE, Thomas DS: Oxidation processes. XVI The autoxidation of ascorbic acid. J Amer Chem Soc. 1943, 65: 1934-1939.
  3. Auersperger I, Škof B, Leskošek B, Knap B, Jerin A, et al. (2013) Exercise-InducedChanges in Iron Status and Hepcidin Response in Female Runners. PLOS ONE 8(3): e58090.
  1. Santhirapala V, Williams LC, Tighe HC, Jackson JE, Shovlin CL (2014) Arterial Oxygen Content Is Precisely Maintained by Graded Erythrocytic Responses in Settings of High/Normal Serum Iron Levels, and Predicts Exercise Capacity: An Observational Study of Hypoxaemic Patients with Pulmonary Arteriovenous Malformations. PLOS ONE 9(3): e90777.
  1. Anna EO Fisher and Declan P Naughton. Iron supplements: the quick fix with long-term consequences. Nutrition Journal 20043:2. Fisher and Naughton; licensee BioMed Central Ltd. 2004

Ciara Delgado is a nationally certified A.C.E. Personal Trainer and Exercise Physiologist residing in Charlotte, NC. She is degreed in Exercise Science from UNC Charlotte and has a dual master’s (Sports Science & Sport’s Studies) from U.S.S.A, Southeast U.S.A Olympic Training Center. With 13 years of training experience, leadership, and international speaking. Ciara is the 2016 & 2017 winner of Elevate Magazine’s #1 Female Trainer of Charlotte, Men’s Fitness Top 21 Trainers, and the Co-Owner of STAG Human Performance.

Photo Credit: J. Lindsay Photography, Charlotte NC.