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Ferritin (Iron)

When an athlete begins to struggle in workouts and races, experiences excessive fatigue, or has a sense of no reserves for hard efforts and their performance drops, iron deficiency should be among the first issues considered.   Endurance sport coaches have long known about the perils of low iron but have often been stymied by a lack of understanding in the medical community for the enhanced need that the serious athlete's body has for replenishing this and other minerals due to higher work output and a variety of other factors.  Iron deficiency is common in athletes, due to increased metabolic effort, sweating, foot strike hemolysis (blood cells crushed underfoot during exercise) and especially in females who have to contend with iron loss associated with their monthly cycles. It is normal for men to have higher levels of iron than women.  


Iron deficiency impedes the body's ability to manufacture red blood cells and can lead to anemia. It has long been acknowledged that hampered performance and safety of training and racing occur with iron deficiency anemia.  However, low iron levels alone have been shown to increase fatigue at numbers well within the normal standard reference ranges on many lab tests and even without the presence of anemia, with normal hemoglobin levels. Recent research supports earlier studies showing that ferritin levels should be at least 40-50 ng/ml, and that lower levels can contribute to restless leg syndrome, infertility, hair loss, fatigue, and immune dysfunction, cold intolerance, decreased thyroid function, and poor memory, again, even in the absence of anemia.  


Vegetarian athletes can also struggle with low iron levels as the form of iron present in vegetables and fruits is not as efficiently absorbed as the type of iron present in meat. Note it is normal for men generally, to have higher levels of iron than women.


All that said, there may be no benefit from iron supplementation to performance or health unless a deficiency or inadequacy is present. Studies have shown that there is no athletic performance benefit to increasing iron stores once levels are adequate.  What has been debated, and what new research has shown is that the adequate level needs to be elevated above the standard lab reference range minimums still in use. Hence our optimum range recommendation.




Iron is the most critical mineral with regards to its effects on sports performance and endurance. Iron deficiency is the world’s most common nutritional disorder and is the most frequently observed nutritional disorder among athletes performing aerobic exercise and resistance training (1,2). Nearly one fifth of recreational athletes have anemia and a third are iron deficient and this can significantly decrease their physical performance (3).  Women (4,5) and adolescents (2,6) are affected most by this, however it is an issue for some male athletes as well.


Iron is required to produce hemoglobin and myoglobin, the metalloproteins responsible for oxygen transport in the blood and muscles.  It is also a constituent of cytochromes and multiple enzymes found in muscle cells which are also critical to oxygen metabolism. Iron further plays a role in the electron transport chain in the body as well as in DNA synthesis.  As such, iron deficiency compromises oxygen transport and metabolism and can trigger a cascade of secondary effects that could decrease sports performance.


Iron reserves in the body exist primarily as bound to the protein ferritin.  Ferritin, this stored form of iron, provides an excellent measure of the body’s iron status as its’ concentration is easily measured with an inexpensive blood test.

Studies have shown athletes to have generally lower ferritin concentrations and hemoglobin than non-athletes (7). Some 11% of male athletes and 35% of female athletes have been found to be iron deficient (8,9). Significant variations in iron status have also been reported during the course of a sports season (10).   A study of high school cross country runners reported 8% of male and 34% of female runners had serum ferritin levels below the standard clinically low level of 12 ng/mL (11). Another study of high school cross country runners found 3% of boys and 40% of girls to be iron deficient at the start of a season increasing to 17% of boys and 45% of girls by the end of the season (12).  A Swiss study found that 28% of female marathon runners were iron deficient (13).


Iron depletion reduces athletic performance capacity and can cause fatigue, exercise intolerance, altered immune function, attention loss, irritability, diminished visual perception, impaired temperature regulation in cold, and reduced ability to adapt to high altitudes (14,15,16,17,18). One of the reasons athletes tend to be more susceptible to low iron is that certain exercise promotes the release of hepcidin.  This hormone, released by the liver, is the main regulator of the body’s iron reserves. It acts by inhibiting iron recycling and absorption. Hepcidin increases due to exercise are dependent on a minimum intensity of around 65% VO2max with maximal hormone levels at 90% to 95% of VO2max and are also affected by exercise duration and load (19).


Other reasons for athletic iron depletion include a small loss with foot strike hemolysis, the loss of some blood cells that get crushed by the pounding of feet to the ground in running, and by training-induced gastrointestinal blood loss.  A German study used radio-labeled iron to evaluate iron turnover in athletes and found a 3-6 fold increase in gastrointestinal blood loss associated with intensive training and racing (20). Among reasons female athletes are more affected than males include low intake of dietary iron (11) and monthly loss of menstrual blood during childbearing years.  


If iron levels stay low, anemia can develop as less red blood cells and  hemoglobin are produced, leading to impaired oxygen transport. An anemia is simply when the number of red blood cells or hemoglobin in a blood sample falls below a certain threshold.  However, the presence of anemia is not necessary for low iron to impact athletic performance and endurance. A condition called iron deficient non anemic (IDNA) has been thoroughly studied and shown to impact performance.  In 2000, a Cornell study followed two groups of iron deficient, non anemic female athletes, one supplemented with iron, the other with placebo, over a 6 week period. The study included athletes with ferritin levels below the standard clinical low value of 12 ng/mL,  spanned 4 weeks of aerobic training and used a 15 Km time trial on a cycle ergometer to assess for performance changes. Results showed significantly increased ferritin levels in the supplemented group. This was accompanied by greater improvement in time to finish the time trial, with greatest benefit to the second and third 5K segments, suggesting significantly increased endurance capacity.  Linear regression analysis was used to show that this benefit was in part due to the increase in serum ferritin level and to a lesser extent, hemoglobin (21). This finding was consistent with the significant, positive association between change in endurance time and serum ferritin levels in runners maintaining their regular training habits as reported by a previous study (22).


Another Cornell study, in 2011, showed that impacts to athletic performance can occur at ferritin levels substantially higher than the current accepted lowest normal level of 12 ng/mL.  A group of 165 female collegiate rowers were assessed for ferritin levels and recent personal bests in a maximal effort 2Km row. Results showed significantly slower 2Km row times (21 seconds slower for a typical 8 minute event) for those athletes whose ferritin levels were below 20ng/mL and that decreased performance was associated with ferritin levels as high as 25ng/mL (23).  In 2014, British Journal of Medicine published a meta-analysis that reviewed some 17 prior studies on iron supplementation in athletes with low ferritin but normal hemoglobin. The conclusion of this study showed a marked benefit from iron supplementation in its’ ability to increase both serum ferritin and aerobic capacity (24). Other iron repletion studies in iron deficient athletes have shown reductions in fat mass and increases in lactate threshold, improved exercise economy, and a 7.4 % increase in VO2max (25, 26, 27).

All of this makes it abundantly clear that there exists a need for a more optimized athletic ferritin range to suit the requirements of competitive athletes.  Evidence shows us that athletic performance is impeded even at double the standard reference range low value. There is an additional complication to the measurement of stored iron and that is the problem of variability of ferritin levels on a day to day basis.  A Penn State University study found day-to-day ferritin levels can vary by as much as 15% in men and up to 27% in women(28). Any meaningful attempt to develop an optimized athletic range for serum ferritin values would need to recognize this.  RunTheLabs factors in the results of the above mentioned research and the proven daily ferritin level fluctuations into our recommended optimal ranges for ferritin.  Our recommended optimal ranges are disclosed in your results.



  1. Beard J, Tobin B. Iron status and exercise. Am J Clin Nutr 2000;72:594-597.  

  2. Zoller H, Vogel W. Iron supplementation in athletes-- First do no harm. Nutrition 2004;20:615-619.  

  3. Manuela Di Santolo, Giuliana Stel, Giuseppe Banfi, Fabio Gonano, Sabina Cauci, 2007, 'Anemia and iron status in young fertile non-professional female athletes', European Journal of Applied Physiology, vol. 102, no. 6, pp. 703-709

  4. Auersperger I, Knap B, Jerin A, Blagus R, Lainscak M, Skitek M, Skof B.The effects of 8 weeks of endurance running on hepcidin concentrations, in ammatory parameters, and iron status in female runners. Int J Sports Nutr & Exerc Metab 2012;22:55-63.  

  5. Auersperger I, Skof B, Leskosek B, Knap B, Jerin A, Lainscak M. Exercise- induced changes in iron status and hepcidin response in female runners. PLoS ONE 2013;8:3.

  6. Anttila R, Cook JD, Siimes MA. Body iron stores decrease in boys during pubertal development: the transferrin receptor-ferritin ratio as an indicator of iron status. Pediatric Res 1991;41:224-228.

  7. Roecker L, Hinz K, Holla K, Gunga HC, Vogelgesang J, Kiesewetter H. Infuence of endurance exercise (triathlon) on circulating transferrin receptors and other indicators of iron status in female athletes. Clil Lab 2002;48:307-312.

  8. Malczewska J, Raczynski, G, Stupnicki R. Iron status in female and endurance athletes and in non-athletes.  Int J Sport Nutr & Exerc Metab 2000:10:260-276 

  9. Malczewska J, Szczepanska B, Stupnicki R, Sendecki W. The assessment of frequency of iron deficiency in athletes from the transferrin receptor-ferritin index.  Int J Sport Nutr & Exerc Metab 2001;11:42-52

  10. Reinke S, Taylor WR, Duda GM, Von Haehling S, Reinke P, Volk HD. Anker SD, Doehner W. Absolute and functional iron deficiency in professional athletes during training and recovery. Int J Cardiol 2012;156:186-191.

  11. Nickerson, H. J.; Holubets, M. C.; Weiler, B. R.; Haas, R. G.; Schwartz, S.; Ellefson, M. E., Causes of iron deficiency in adolescent athletes. The Journal of pediatrics 1989, 114 (4), 657-663.

  12. Rowland, T. W.; Black, S. A.; Kelleher, J. F., Iron deficiency in adolescent endurance athletes. Journal of Adolescent Health Care 1987, 8 (4), 322-326.

  13. Mettler, S.; Zimmermann, M., Iron excess in recreational marathon runners. European Journal of Clinical Nutrition 2010, 64 (5), 490-494.

  14. Deakin V. Iron depletion in athletes. In: Burke L, Deakin V. Clinical Sports Nutrition. Sydney: McGraw-Hill; 2006. P. 174-199.

  15. Murray-KolbLE,BeardJL. Iron treatment normalizes cognitive functioning in young women. Am J Clin Nutr 2007;85:778-787.

  16. Schumacher YO, Chmid A, Granthwohl D, Bültermann D, Berg A. Hematological indices and iron status in athletes of various sports and performance. Med & Sci Sports Exerc. 2012;34:869-875.

  17. Stray-GundersenJ,HochssteinA,deLemosD,LevineBD. Failure of red cell volume to increase to altitude exposure in iron deficient runners. Med & Sci Sport & Exerc 2002;24:90.

  18. WilliamsMH.Dietary supplements and sports performance, minerals. JInt Society Sport Nutr 2005;2:43-49.

  19. Domínguez, Raúl & Vicente-Campos, Davinia & Chicharro, José. (2014). Hepcidin Response to Exercise: A Review. Turkish Journal of Endocrinology and Metabolism. 18. 84-91. 10.4274/tjem.2438.

  20. Nachtigall, D.; Nielsen, P.; Fischer, R.; Engelhardt, R.; Gabbe, E., Iron deficiency in distance runners a reinvestigation using 59Fe-labelling and non-invasive liver iron quantification. International Journal of Sports Medicine 1996, 17 (07), 473-479.

  21. Hinton, Pamela S., Christina Giordano, Thomas Brownlie, Jere D. Haas, Iron supplementation improves endurance after training in iron-depleted, nonanemic women. Journal of Applied Physiology Published 1 March 2000 Vol. 88 no. 3, 1103-1111

  22. Rowland, T. W., M. B. Deisroth, G. M. Green, and J. F. Kelleher. The effect of iron therapy on the exercise capacity of non-anemic iron-deficient adolescent runner. Am. J. Dis. Child. 142: 165-168, 1988.

  23. Dellavalle, D. M.; Haas, J. D., Impact of Iron Depletion Without Anemia on Performance in Trained Endurance Athletes at the Beginning of a Training  Season: A Study of Female Collegiate Rowers. International Journal of Sport Nutrition and Exercise Metabolism 2011, 21, 501-506.

  24. Burden RJ, Morton K, Richards T, et al Is iron treatment beneficial in, iron-deficient but non-anaemic (IDNA) endurance athletes? A systematic review and meta-analysis Br J Sports Med 2015;49:1389-1397.

  25. Hinton, P.S., Sinclair, L.M.  Iron Supplementation Maintains Ventilatory Threshold and Improves Energetic Efficiency in Iron-Deficient Nonanemic Athletes. Eur J Clin Nutr. 2007 Jan:61(1):30-9. Epub 2006 July 12.

  26. DellaValle, D.M., Haas, J.D. Iron Supplementation Improves Energetic Efficiency in Iron-Depleated Female Rowers. Med Sci Sports Exerc. 2014 Jun;46(6):1204-15.

  27. Wachsmuth, N.B., Aigner, T., Volzke, C., Zapf, J., Schmidt, W.F., Monitoring Recovery From Iron Deficiency Using Total Hemoglobin Mass. Med Sci Sports Exerc. 2015 Feb;47(2):419-27.

  28. Borel, M. J.; Smith, S. M.; Derr, J.; Beard, J. L., Day-to-day variation in iron-status indices in healthy men and women. The American journal of clinical nutrition 1991, 54 (4), 729-735.


How we assess Iron status:


Serum Ferritin = protein used to store iron= early indicator of iron deficiency or overload  


Ferritin is the body's mechanism for storing iron.  It is a protein that stores a reserve of iron in excess of the body's immediate daily needs, which is roughly 30 percent of the body's iron (in healthy individuals).  Ferritin is also perhaps, the best early indicator of issues with one's iron status, capable of detecting subtle deficiencies or excesses. Serum ferritin, a common and easily performed lab test,  provides a reliable albeit indirect measure of iron stored in organs and other soft tissues of the body. Generally, for healthy individuals, it is accepted that the amount of ferritin found in a blood test is an accurate and reliable measure of iron status throughout the entire body.  When your ferritin levels are in the optimal range, you have enough, but not too much, iron in your body. If ferritin levels are too low, you are short on iron. Because ferritin is what is known as an "acute phase reactant," it's number can be elevated in the body due to infection or other disruptions to good health.  It is therefore important to time this test during periods of good general health for purposes of accuracy. Standard normal reference ranges assigned by labs often run from about 10 to 200 ng/ml for females and 20 to 300 ng/ml for males. Laboratory ranges do vary, however most are close to these values. Standard reference ranges are merely statistical approaches to populations being tested in a given region.  They are designed to capture 90-95 percent of the results in a given region being tested as "normal." Therefore the athlete putting in 40-70 miles per week is looked at the same as someone in the end stages of a chronic disease with regards to where their numbers should be. With exception for the lowest part of normal ranges, which can be associated with clinical issues like anemia in this case, the standard ranges do not equate to optimal or even healthy iron levels for an athlete. The RunTheLabs recommended optimal range for serum ferritin is 60-190 ng/ml for males and 50-150 for females.

Dietary Recommendations for Optimal Iron Status:


There are two forms of iron present in food,  heme iron and non-heme iron. Heme iron is found in meats, fish, poultry. Estimates vary but there are good indications that  roughly 25% of heme iron ingested is absorbed ()though some studies suggest this number to be a good bit higher. The iron present in fruits, vegetables and most supplements is non-heme iron.  Non-heme iron is absorbed at a much lower rate, thought to be somewhere between 2-20%, with many studies indicating the lower portion of this range to be more accurate(). People with severe iron deficiencies absorb heme and non-heme iron more efficiently and are more sensitive to dietary enhancing factors than people with better iron status(). Iron absorption is subject to influence by other dietary variables as well.  For instance, the presence of Vitamin C in the same meal can boost non-heme iron absorption by two to ten times. Studies have shown a single 100 mg dose of vitamin C to increase iron absorption by over 4 times(). Alcohol also enhances iron absorption. The presence of calcium reduces heme and non-heme iron absorption by half or more. As little as 300 mg of calcium, or roughly the amount in a cup of milk, is all that is required for this inhibitory effect.  Therefore food and or supplementation combinations must be considered. Significantly less iron will be absorbed if an iron supplement were consumed with a calcium supplement, and the same goes for eating a cheeseburger versus a plain hamburger (F). Some dietary factors chelate with or bind to non-heme iron, inhibiting absorption of iron as well as other minerals. These "antinutrients" include: the phytates and fibers in whole grains, cereals and nuts, beans and soy;  polyphenols, such as those found in cocoa, coffee, black, green and herbal teas, apples, walnuts and berries; the EDTA in food additives; tannic acid present in tea, coffee, nuts, and some fruits and vegetables; and oxalates which are high in foods such as spinach, kale, beets, nuts, chocolate, tea, wheat bran, rhubarb, straw berries and herbs such as basil, parsley and oregano. A single cup of coffee within an hour or two of an iron rich meal, can inhibit iron absorption by as much as 60% and tea by up to 90%.  Beta-Carotine, a yellow-red pigment contained in foods such as tomatoes, beets and beet greens, carrots, red peppers, corn, yellow squash, oranges, peaches, prunes, collard greens, spinach, sweet potatoes, apricots, turnip greens and red grapes, has been shown to significantly increase the absorption of iron and in the presence of phytates or tannic acid, beta-carotene can overcome the inhibitory effects of both compounds depending on their concentrations. Studies have also shown higher absorption of iron supplements when they are consumed with fruit, leading some to recommend small doses of nutrient dense sugars such as honey, black strap molasses or antioxidant rich fruit to iron rich meals.  


So, to recap, Iron is most readily absorbed from meats, especially red meat, since it is the best source of heme iron, the most biologically-available form and most easily absorbed.  Of the iron in meat, about 40-45 percent is in heme iron form. People with normal iron absorption pull in about 20-25 percent of the heme iron consumed. Consuming meat also significantly improves the absorption of non-heme iron present in the same meal. There are many powerful nutritional influences on iron absorption that need to be considered.  Vegetarian athletes run a higher risk for iron deficiency, due to the significantly lower non-heme iron absorption rate and the various things that can inhibit it which are typical to common vegetarian fare. Many vegetarian athletes train and perform at a high levels safely, but vegetarian women of childbearing years especially, should test their levels frequently and supplement when indicated.

Tips for raising low iron levels safely and naturally:


If a person is iron deficient he or she will want to incorporate substances or foods that increase or improve iron absorption and avoid foods or substances that impair absorption.

Some prudent dietary guidelines to increase iron intake and absorption include:


  1. Eat meats, preferably organic, free range, grass fed beef and similar sources of other meats, poultry and wild fish.

  2. Eat other foods known to be high in iron but low in iron absorption inhibiting compounds.

  3. Eat vitamin C containing foods or take supplemental vitamin C (100 to 250mg per meal) with iron containing meals

  4. Use cast iron cookware

  5. Reduce coffee and tea intake at meals that include iron

  6. Avoid significant calcium containing foods or supplements at meals with iron.

  7. Limit eggs at times when other iron containing foods are eaten as one boiled egg can reduce absorption of iron in a meal by as much as 28%.

  8. Consume a small dose of a healthy form of sugar such as a drop of honey, black strap molasses, or antioxidant rich fruit with your iron rich meal or supplement.

  9. Limit foods rich in phytates which reduce iron absorption about 50% (nuts, seeds, legumes, cereals, whole grains) in meals rich with iron.

  10. Limit foods rich in oxalates such as spinach, kale, beets, nuts, chocolate, tea, wheat bran, rhubarb, strawberries and herbs such as oregano, basil, and parsley at meals rich in iron.

  11. Limit polypenols for the same reason.  Foods rich in these antinutrients include cocoa, coffee, black tea, herbal teas, green tea, berries, walnuts, apples.

  12. Consume foods rich in beta-carotine, especially when phytates or tannins are present in the same meal.  

  13. If hypochlorhydria or achlorhydria is suspected based on symptoms and experimentation with Betaine HCL,  supplement in a dose dependent fashion at mealtime in accordance to the size of the meal and it's protein content.  Remember, if the belly gets a warm or burning sensation, you have taken at least one too many betaine hcl tablets.

  14. Avoid drinking cold water as it decreases stomach acid production and consume only small amounts of water with meals so as to not overly dilute the HCL.

  15. Consume a quality iron supplement.  RunTheLabs prefers Iron Carbonyl for safety and easy absorption.  Take the supplement in the evening on an empty stomach or with some Vitamin C for best absorption.  



Don’t Just Take Iron Supplements, Get Tested First:

The Flip Side of Iron: Iron Overload and Hemachromatosis


There can however be too much of a good thing.  Individuals with risk factors for diabetes, cardiovascular diseases, stroke, liver diseases and cancer face amplified risks proportional to the amount of stored and free iron in the body over and above the optimal range. This fact can not be over emphasized.  High iron is thought to be as common as iron insufficiency in the general populous, but it is typically more dangerous. Some research has demonstrated that those with such risk factors listed above can increase their chances of developing these conditions at serum ferritin levels above 100 ng/ml due to iron's role in oxidative stress.  With current lab reference ranges suggesting that ferritin levels are "normal" up to 200 to close to 400 ng/ml in some cases, one can see how inadequate the standard ranges are for purposes of health optimization. The risks mentioned above are not typical of most people routinely engaging in competitive endurance athletics. However, for those with known risk, or who haven't paid much attention to their general health status in past years, when ferritin levels are high, a simple check of a liver enzyme known as Gamma Glutamyl Transferace  (GGT) can give a good indicator of one's natural antioxidant capacity or ability to thwart the enhanced oxidative stress posed by excess iron in the system. GGT levels are utilized by some as a surrogate test of the body’s ability to recycle glutathione(), a powerful antioxid t. Low-normal GGT levels can indicate better tolerance of iron in the body and an intact antioxidant system for countering oxidative stress. Therefore, low-normal GGT indicates a greater ability to tolerate the presence of iron in the system. Those with elevated GGT, above the optimal range, may want to adjust their Ferritin optimum range to 50-100ng/ml.


An estimated one million people in the United States have hereditary hemochromatosis (HH). Hereditary hemochromatosis is a genetic disease that alters the body's ability to regulate iron absorption, causing it to absorb too much. If correctly diagnosed, it is easily and effectively treated, but if untreated, it can lead to severe organ damage over time. Caucasians of northern European descent are at highest risk.  Serum ferritin levels alone are not diagnostic for HH but a level of more than 200 ng/ml for women and 300 ng/ml for men is considered out of range. Above these levels one may want to consult their primary care physician for follow up. Though it is thought to be rare for organ damage to occur with ferritin levels below 1000 ng/ml, RunTheLabs contends that the scientific jury is still out on this and that safer upper limits are likely  below the standard upper lab reference range limits. We strongly encourage anyone over the standard reference range high values, to employ some of our dietary recommendations to limit iron absorption as well as to consult their primary care practitioner(PCP) for a proper clinical work up.  Generally, iron overload is easy and inexpensive to monitor and treat. In addition to the dietary recommendations for excess iron, and avoiding iron containing supplements, routine blood donation can also help keep iron loads regulated. Adult males, for instance, can often maintain their healthy iron levels by donating two to three times per year once their optimum range has been achieved().  If ferritin levels are over 200 for women and 300 for men more aggressive management may be required and especially if there are other complicating factors in an individuals health profile, consultation with a physician skilled in the management of iron overload should be sought. Safety first! The point of your athleticism should be to attain optimal performance while also benefiting from maximal health and wellness.

Tips for naturally lowering elevated iron levels:


If a person has abnormally high body iron levels, he or she will want to consume foods or substances that lower the amount of iron absorbed in order to reduce the iron load and the oxidative stress from the excess iron:


  1. Increase consumption of the spice turmeric or supplement with curcumin as they have been shown to increase iron excretion.

  2. Cease using iron cookware.

  3. Decrease consumption of foods that are high in iron, especially readily absorbed heme iron.  Red meat has the highest level of iron which is great if your iron levels are low, but not so great if they are too high.

  4. Lower your net carb intake and increase your consumption of healthy fats, including animal-based omega-3, to switch over to fat-burning mode and protect your cells from oxidative stress.

  5. Don't combine naturally occurring or supplemental vitamin C with meals rich in iron.

  6. Phytic acid, an antinutrient found richly in unsoaked, unfermented nuts, seeds and grains, such as in whole wheat bread and corn tortillas, inhibits absorption of many minerals by binding with them in the gut.  Consumption of these foods can help limit iron absorption but will also cost you some of the other mineral content in the meal.

  7. If consuming iron rich meats, mix in calcium rich foods to decrease heme iron absorption. Though we do not advocate much dairy in the diets of serious athletes foods rich in calcium include: milk, yogurt, cheese, sardines, canned salmon, tofu, broccoli, almonds, figs, turnip greens and rhubarb

  8. Eat oxalate rich foods such as spinach, kale, beets, nuts, chocolate, tea, wheat bran, rhubarb, straw berries and herbs such as basil, parsley and oregano to decrease iron absorption. Oxalic acid is another mineral binding antinutrient.

  9. Use eggs as a protein source as they contain a protein, phosvitin, which binds iron and prevents absorption.

  10. Avoid alcohol, sugar, nicotine, and beta-carotene around iron rich meals as all increase the absorption of iron.

  11. Antinutrient polyphenols, such as those found in cocoa, coffee, black, green and herbal teas, apples, walnuts and berries also inhibit iron absorption by binding with minerals like iron in the gut.

  12. Regularly screen for iron overload with a serum ferritin and GGT level to confirm that you don’t have excess iron.

  13. If iron levels remain high, try donating blood, or if significantly elevated consult a physician who is familiar with iron overload and hemachromatosis.

  14. If you are an adult male or non-menstruating woman, it may benefit you to donate your blood at least twice a year.


Iron Supplementation:


If you have been tested and have found your ferritin to be lower than the optimum range, in addition to following the nutritional tips for increasing iron absorption you can also  supplement. There are several forms of iron on the market including iron salts, chelated iron, various preparations of elemental iron and even heme iron. Be aware, iron supplementation can sometimes lead to gastric upset, constipation, nausea, abdominal pain, vomiting and faintness.  In our experience constipation and gastric upset are the most common side effects but there are work arounds for these issues. As well black stools are common while supplementing iron and are considered normal.


Iron salts, such as ferrous sulfate, ferrous gluconate and ferrous fumerate are the combinations of iron with another molecule to form a salt soluble in water.  Of them, Ferrous Sulfate is most commonly used. Iron salts are typically inexpensive, readily available, reasonably well tolerated and therefore form a common choice for iron supplementation.  These are available in tablet, capsule and even liquid form for those that struggle with swallowing pills.


Chelated iron contains iron that is tightly bound to larger organic complexes such as amino acids.  Iron bis-glycinate is a common form of chelated iron. These are proposed to be better tolerated than iron salts though evidence is scant.  The thinking is that the strong bond with the chelating agent will take more time to break down giving a more controlled release of the iron,  slowing exposure of the gut lining to the iron component thus enhancing tolerability. This could also be thought to aid in increasing absorption as if taken with a meal. The delay in breakdown could have iron available for absorption in the gut, outlasting some of the iron inhibiting components to the foods just eaten. As this will be less soluble than iron salt in water it may require a more intact production of gastric HCL to breakdown effectively.


There is a heme iron product on the market in the U.S. and Canada.  Branded "Proferrin" this product uses Heme Iron Polypeptide extracted from porcine RBCs to provide the most biologically active form of iron.  The use of heme iron as a supplement eliminates the need take on an empty stomach or for vitamin C supplementation concurrent with the iron dose.  If taken with a meal, the heme iron should also increase the absorption of non-heme iron present in the foods eaten. This product is considered a medical food and not a supplement.  


The RunTheLabs preferred form of iron is carbonyl iron for its' excellent absorption, tolerability due to slower availability/absorption, and safety. Carbonyl iron is a highly pure elemental iron prepared by chemical decomposition of purified iron pentacarbonyl.  It is low in cost and offers significantly reduced risk of poisoning in children over iron salts due to its slow absorption. The Douglas Labs product Timed Release Iron is carbonyl iron and is a favorite of ours for low cost and generally good tolerability.


Iron product labels typically contain two values.  One represents the amount to the total product or size of the tablet, capsule or dose.  The other is the actual amount of elemental iron contained. A common approach to dosages for iron deficiency anemia is between 60mg-200mg of elemental iron per day depending on the severity of the deficiency and or individual response.  Doses of no more than 60mg at a time are preferred to be taken on an empty stomach or accompanied by a 200-500 mg Vitamin C supplement. Some use orange juice to aid absorption. The higher daily amounts in this range typically promote greater gastrointestinal(GI) upset, constipation, diarrhea, epigastric pain, etc.  On encountering GI symptoms one could choose from several adjustments to the protocol. First one could simply drop the dosage or frequency of dosage. Also, review the information on low HCL to be reasonably sure that it isn't an issue for you. You could also change product to a different form of iron. Or you can take the supplement with a meal, preferably in the presence of heme iron from meat, vitamin C and beta carotene containing foods and in the absence or low presence of those foods discussed to impede iron absorption.  


In order to safeguard against hampering one's training or performance with supplement related GI distress RunTheLabs recommends athletes begin slowly, with a single small dose of any particular nutritional product to challenge tolerance.  This can be done for a few days before adding to the dosage or the frequency of ingestion. We would advise against beginning such supplementation within several days of a significant race event as tolerance issues may distract from effort or performance at race time.  Part of determining dose and frequency should be how far under the optimum range the athlete tests for serum ferritin but also experimenting with a dose schedule they are able to tolerate. For those without anemia but with iron deficiency, our recommendation is for the lower dose mentioned in the range above or roughly 60mg of elemental iron per day.  It is not uncommon for us to find significant benefit for individuals taking a single 2 tablet dose of Time-Released Iron on empty stomach to rectify moderately low ferritin levels. Iron replenishment is slow and typically significant change will take 6-8 weeks or more. Rechecking serum ferritin 6-8 weeks out from initiating supplementation may help to dial in on a strategy that works for you.  Periodic reassessment until optimal levels are reached and maintained are well advised. Adjustments can then be made to the dose and schedule based upon these values.


If at any point an athlete feels stymied in their ability to utilize the information provided here to adequately lift low iron levels, they are encouraged to seek the guidance of a sports physician or other clinition, well versed in iron balance issues.  As well if iron status assessing values should fall significantly or consistently while supplementing and working one's diet to improve absorption, this would also be a situation best dealt with by working with your physician.


Iron supplementation can compete with zinc absorption and long term use of iron supplements should be accompanied by a multivitamin with some zinc.  As this would likely also contain calcium take it at a different time of day than the iron. Note also that severe overdoses of iron can lead to multisystem organ failure, coma, convulsions, and even death.  The FDA currently requires that iron-containing dietary supplements sold as tablets or capsules have a label warning: "WARNING: Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6. Keep this product out of reach of children. In case of accidental overdose, call a doctor or poison control center immediately". In addition, since 1978, the Consumer Product Safety Commission has required manufacturers to package dietary supplements containing 250 mg or more elemental iron per container in child-resistant bottles or packaging to prevent accidental poisoning.


Iron Interactions with Medications:

Iron can interact with some medications and certain medications can present adverse effects on iron levels.  A few examples include:



Evidence indicates that in healthy people, iron supplements reduce the absorption of levodopa, used to treat Parkinson’s disease and restless leg syndrome, possibly through chelation. In the U.S., levodopa labels warn that iron-containing dietary supplements might reduce the amount of levodopa available to the body and, thus, diminish its clinical effectiveness.



Levothyroxine  is used to treat hypothyroidism, goiter, and thyroid cancer. The simultaneous ingestion of iron and levothyroxine can result in clinically significant reductions in levothyroxine efficacy in some patients. Calcium can also produce similar inhibitory effects.  The labels for some levothyroxine products warn that iron supplements can reduce the absorption of levothyroxine tablets and advise against administering levothyroxine within 4 hours of iron supplements.


Proton pump inhibitors:

Gastric acid plays an important role in the absorption of nonheme iron from the diet. Because proton pump inhibitors, such as lansoprazole  and omeprazole, reduce the acidity of stomach contents, they can reduce iron absorption [3]. Treatment with proton pump inhibitors for up to 10 years is not associated with iron depletion or anemia in people with normal iron stores but patients with iron deficiency taking proton pump inhibitors can have suboptimal responses to iron supplementation or nutritional strategies aimed at increasing iron levels..


Anemia of chronic disease:


Certain inflammatory, infectious, auto immune and neoplastic diseases can cause anemia of chronic disease, also known as anemia of inflammation.  This type of anemia is the second most common after that which is caused by iron deficiency. This condition causes a disruption in iron handling pushing up iron stores and making iron unavailable for the production of new RBCs.  It can be difficult to diagnose as serum ferritin levels tend to be higher in patients with infection or inflammation. Therefore it is unlikely that an athlete with this form of anemia would be recommended supplementation or iron enhancing nutritional strategies as their ferritin levels and GGT would likely be elevated and not diminished by the presence of chronic disease. If your results include optimal or elevated ferritin, folate and B12 levels but significantly low hemoglobin and or hematocrit, you should consult your primary care physician to rule out any infection or chronic disease.  


Hydrochloric Acid (HCL): Vital to digestion and absorption


Hydrochloric acid (HCl) is an vital gastric secretion that enables the body to break down proteins, activate important enzymes and hormones, absorb essential vitamins and minerals and protect against bacterial overgrowth in the gut.  Lack of adequate hydrochloric acid or hypochlorhydria is a common phenomena due to the modern western diet, medications, and certain stress factors. Achlorhydria, or the absence of stomach acid is a severe form of this and becomes more common as we age becoming most prominent among the elderly.  Both of these conditions can dramatically lower the absorption of micro and macronutrients from our foods or supplements. It is thought that roughly a third of people over 60 years old have achlorhydria and significantly more have hypochlorhydria. Total digestion is affected but protein digestion is especially compromised by low HCL levels and many vitamins and minerals such as vitamin B12, folate, calcium, magnesium and iron require an acidic environment for adequate absorption.  Medications that reduce stomach acidity are a common cause of this problem and "ant-acid" use is now linked to decreased bone density as a result. Any medication can contribute to lower stomach acid and this condition also can lead to iron and vitamin B12 deficiencies and their associated anemias, amino acid deficiencies, intestinal permeability and food sensitivities, small intestine bacterial overgrowth, and dysbiosis of the colon.


A complicating factor that leads many down a wrong path of self treatment with over the counter ant-acids is that the symptoms of hypochlorhydria and excess stomach acid (hyperchlorhydria) are very similar and many will treat for too much HCL when in fact they didn't produce enough to adequately digest to begin with.


Hydrochloric acid has been shown to be effective in relieving symptoms associated with achlorhydria and hypochlorhydria. Substances shown to support healthy acid secretion and digestion include:

Betaine hydrochloride

Betaine hydrochloride (HCl) is a nutritional supplement that has been used for over 100 years to safely restore normal gastric acidity and to support healthy gut function. Betaine HCl should not be confused with another popular nutritional supplement, anhydrous Betaine, a methyl-donor nutrient taken to control homocysteine levels.


Pepsin has a long history of medicinal use and is considered very safe when administered to assist digestion, typically in conjunction with hydrochloric acid.


Hydrochloric acid (HCl) is an important gastric secretion that enables the body to break down proteins, activate important enzymes and hormones, and protect against bacterial overgrowth in the gut. Achlorhydria (the complete absence of stomach acid) and hypochlorhydria (low stomach acid) are common digestive problems. Symptoms of low stomach acid include heartburn, indigestion and bloating, burping, diarrhea, flatulence, rosacea, weak or cracked fingernails, and nausea on taking nutritional supplement.


Low HCL checklist:


If a few of these apply to you, you may want to considering supplementing at meal time with Betaine Hydrochloride(HCL):

  • Burping

  • Abdominal bloating especially after eating protein

  • Sense of fullness long after eating

  • Diarrhea or Constipation

  • Indigestion

  • Flatulence, develops rapidly

  • Nausea, especially on taking supplements

  • Slow digestion

  • Undigested food in stool

  • Halitosis

  • Acne

  • Loss of appetite for meat

  • Rosy cheeks with capillary dilation

  • Weak, peeling or cracked or fragile fingernails




If hypochlorydria is suspected one can experiment in a couple of ways to determine if this is likely the case.  First, if suffering with heartburn, one can take a tablespoon of fresh squeezed lemon or lime juice. If there is worsening of the symptoms you are likely not hypochlorhydric. Another test is with betaine hydrochloride supplementation by taking a single dose at the start of a meal.  If a warm or burning sensation occurs you are likely not suffering with low stomach acid. If not, you can add in another dose at the midpoint of the next meal. If no unpleasantness results, this can be done with up to a few more doses spread throughout the mealtime of future meals.  If any symptoms had been caused by hypochlorhidria, they should be diminishing or relieved and you can stop at a dose per meal size that seems to work for you. At some point, with the addition of increased doses per meal, one may experience warmth or heart burn type symptoms and this can help guide the upper limit of  dosage per meal, simply take one less than you had at the next meal of similar size and protein content. You are now on your way to more proper digestion of your foods and therefore better absorption of the nutrients your body relies upon.

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