Overcoming Iron Deficiency

sarah cuff Performance, Supplements, Training 17 Comments

Nearly 2 months ago I discovered I was clinically iron deficient. Although I’d been struggling with fatigue over the past number of months, many of the strategies I’d implemented to combat fatigue had appeared to help – so I thought I was in the clear. But alas, I was not. However, iron deficiency explained so much – and after quickly and properly addressing this deficiency I’m finally at a point where I feel like I’m getting my speed back and running faster again (and I no longer feel like I need a nap everyday!!).


I’ve talked in the past about how to boost iron levels – but what I’ve noticed is those runners who are diagnosed deficient don’t always get good direction on what supplements / how much to take daily. And in order to overcome iron deficiency or anemia, these details are really important! Obviously diet is important too – so today I want to share with you both what types and amounts of iron to look for in supplements, as well as nutritional strategies to overcome iron deficiency. But first – causes, symptoms and how to diagnose iron deficiency!

Causes of Iron Deficiency 

There are many reasons behind iron-deficiency including:

  • inadequate iron intake (not eating enough iron-rich foods)
  • poor iron absorption (due to inflammation in the gut, celiac disease, etc) and blockage of iron absorption due to hepcidin bursts (hepcidin is a hormone that regulates iron absorption)
  • loss of iron through blood (female runners may struggle more with iron-deficiency due to menstruation)
  • destruction of red blood cells through foot strike, called hemolysis (common in runners, particularly those who run high-mileage)
  • loss of iron through sweat (not significant amounts, but relevant to those running in constant hot humid climates)
  • bleeding in the digestive tract (such as from chronic NSAIDs or aspirin use, or from Crohn’s or colitis, etc)

Symptoms of Iron Deficiency in Runners

If you think you might be iron-deficient, there are a few tell-tale signs to look for such as:

  • fatigue (feeling excessively tired despite plenty of rest)
  • breathlessness in training
  • unexplained drop in performance
  • faster than normal heart beat
  • weakness
  • pale skin
  • PICA (a craving for ice or dirt or other nonfood items)
  • tingling in legs
  • cold hands and feet
  • headaches
  • brittle nails

Someone who is severely iron deficient may experience all the above symptoms while someone who is in the first stages might experience very few if any symptoms at all. More symptoms present themselves as the iron deficiency becomes more severe.

Diagnosis of Iron Deficiency and Anemia

If you think you may be iron deficient, do NOT self-diagnose! You must go to your doctor and ask for blood work to be done in order to find out what your ferritin (stored iron) and hemoglobin (oxygen carrying protein in red blood cells) numbers are. The symptoms for too much iron are similar to not enough iron – and too much iron can be deadly. Approximately 0.3% and up to to 16% in caucasian men and 0.3% and up to 30.4% in caucasian women has a hereditary condition called hemochromatosis (this gene is rare in other races) – in which the body inappropriately stores too much iron. Clearly, taking iron supplements if you unknowingly have hemochromatosis would be a bad idea.

Of course iron deficiency is far more common than hemochromatosis. It’s estimated up to 82% of endurance athletes are iron deficient, although a much lower percentage, only 2-5%, are suffering from iron deficiency anemia. Once the results of your blood test come back, your doctor will let you know if you are iron deficient or anemic. At that point he/she may recommend a supplement or that you ought to supplement, and will probably tell you to eat more iron-rich foods also. Sometimes they’ll go into detail… Sometimes not. More on food in a minute. First, a bit of background on what constitutes iron deficiency.

According to Louise Burke in Clinical Sports Nutrition (4th ed)¹, the guidelines for diagnosis are as follows:

Iron deficiency is when low levels of ferritin (storage form of iron) are found. Generally normal levels are considered above 12 mcg/L, although Burke suggests normal is above 22 mcg/L. Not all agree on exactly what level constitutes “low” or “normal” (although most agree that below 15 indicates clinical iron deficiency). I got my blood tests back from Life Labs and their diagnostics on my results were as follows:

  • <15: diagnostic of Iron Deficiency (my results were flagged here as my ferritin levels were 13 mcg/L) 
  • 15-50: Probable Iron Deficiency
  • 51-100: Possible Iron Deficiency
  • >100: Iron Deficiency unlikely

According to this recent 2015 study, healthy male and female adult athletes who have ferritin values of less than 15 mcg/l means their iron stores are equivalent to empty, while values from 15-30 indicate low iron stores. Therefore 30 mcg/l can be used as benchmark for iron deficiency. However, elite adult athletes should ensure they have ferritin values of at least 50 mcg/L before attempting altitude training (iron demands are increased at altitude).

While ferritin levels tell us where our stored iron levels are at, our hemoglobin numbers tell us if we are actually in a stage of iron deficiency anemia (IDA), which is when there is insufficient hemoglobin to meet our bodies needs. According to Burke, normal levels range from 120-160 g/L (12.0-16.0 g/dL). Again, there is no agreement across the board on what normal ranges should be – renowned running coach Jack Daniels, in Daniels’ Running Formula (3rd ed)², advises optimal performance is seen when the runners levels are between 135-160 and that runners are often considered anemic when they have hemoglobin values below 130. He goes on to say that from a running performance point of view, a drop in 10 g could equal a loss of 30-40 seconds over the 5k distance. My hemoglobin levels came in at 125 g/L – not quite IDA according to some benchmarks, but definitely below Jack Daniels standards.

To complicate matters, sometimes an athlete may present with sports anemia, which is an increase in blood plasma volume, diluting red blood cells and ‘watering down’ measures of hemoglobin. In this case, iron supplementation has NO benefit to performance. Additionally, there are other values your doctor will test for, such as low B12, low hematocrit, low serum iron, or low iron saturation, to ensure an appropriate diagnosis.

As you can see, it is important to visit your doctor and have them diagnose you as diagnosis is not straightforward. Therefore, do not attempt to self diagnose.

Supplementation to Overcome Iron Deficiency 

Once you’ve received the diagnosis of iron deficiency or IDA, the fastest way to bring your levels back to normal is by supplementing. According to Burke, recovery should take between 2 to 3 months using high doses of iron (whereas if one were to use dietary measures alone, it would likely take 2 to 3 years).

There are many forms of iron on the market such as ferric pyrophosphate, carbonyl iron, ferrous gluconate, ferrous fumarate, ferrous sulfate and s. cerevisiae (a cultured yeast form). Serving sizes range from as little as 8mg to 300mg (dosages above 40mg or so are typically not available on a drug store shelf but from behind the pharmacy counter). Some contain B12 and/or folate and/or vitamin C. With so many to choose from, how do you know what is right for you?

Burke advocates taking around 100 mg of elemental iron daily for more than 3 months, although doses of up to 300 mg are used in severe cases. Along the same lines, according to this PubMed article it’s common to prescribe a daily dose of 150-200 mg of elemental iron to an adult who is suffering from iron deficiency, taking approximately 60 mg 3 times daily. If there are no complications, the iron deficiency could be fully corrected in as little as 4 weeks using this method.

The ferrous forms of iron are absorbed better than ferric forms, at a rate of between 10 to 15%  (ferric forms are only absorbed at a rate of 2.5% to 3.75%). Specifically, ferrous sulfate is often prescribed as the best form to take for absorption and this 2015 study found that although ferrous sulfate is often looked at as the gold standard for iron supplementation, it causes a significant increase in gastrointestinal side effects. However, according to this study and this study, ferrous bisglycinate is absorbed just as well as ferrous sulfate but causes less gastrointestinal complaints.

Of course it’s well known that a common problem with iron supplementation is the almost inevitable side effect of constipation, nausea, stomach cramping, diarrhea, and heartburn among other unpleasant side effects. This clearly can have a negative impact on training let alone daily comfort levels and thus some people will neglect to supplement regurlary – meaning iron deficiency remains a problem.

Therefore, to ensure compliance and as few gastrointestinal complaints as possible, I recommend using iron in the form of bisglycinate and taking at least 100 mg if not 150-200 mg daily for iron deficiency, depending on how severe your iron deficiency is (possibly more if IDA). If you are low but not clinically iron deficient and want to prevent anemia, a dosage of 30-60 mg daily should suffice. That said, each person is in a unique situation and should receive supplementation guidance based on their blood test results. It should go without saying also that the reason behind the iron deficiency or IDA should be addressed also.


Personally, I’ve been taking 50-60mg bisglycinate 3-4 times per day for the past 2 months with really good results based on how I’m feeling (that said, in another month I’ll get my blood tested again for a clear indication of progress). Very specifically, I’ve primarily been using Platinum Naturals EasyIron (18 mg bisglycinate + 800 mcg folate, 1000 mcg B12, 50 mg vitamin C and 25 mg B6 per capsule) with SISU Gentle Iron (25 mg bisglycinate per capsule). Vitamin C enhances the absorption of iron, however (per this 2012 meta-analysis) be sure not to take more than 1000 mg vitamin daily, as it may inhibit the fitness gains normally associated with exercise and impair performance.

Nutritional Strategies to help Boost Iron Levels

It’s estimated that in general we eat 5-15 mg of elemental iron and 1-5 mg of heme (animal sourced) iron daily. Female endurance athletes require 23 mg and male endurance athletes require 17.5 mg – so chances are many people aren’t eating enough iron rich foods on a daily basis. I’ve outlined many of the iron-rich foods we have to choose from in a list below:

Of course I’ll now be the first now to admit that it’s possible to actually be eating enough dietary iron daily and still suffer from iron deficiency. I’ve continued eating all my iron rich foods including my chocolate cherry berry recovery shakes, tropical green smoothies and iron-rich protein bars as well as lots of leafy greens daily, hemp hearts, almonds, oats, eggs, cacao, salmon – and I also was and am still currently eating bison a couple times weekly. Interestingly, although low ferritin is more common among vegetarians, the incidence of iron deficiency anemia is prevalent equally among meat eaters and vegetarians alike. Or in other words, according to this study and this study, iron deficiency anemia is no more common in vegetarians than in meat-eaters.

When I first received the diagnosis of iron deficiency, you might think my first thought was to stop training in order to allow myself every chance of rebuilding levels as fast as possible. Haha, yah nope, that thought never even crossed my mind! After a bit of research I was confident I could maintain my current training schedule (which at the time consisted of near daily easy runs – no speed workouts, given how I was feeling) and still boost my iron levels. But of course just because that’s what I did doesn’t mean you should too. Again, each person with iron deficiency is in a unique situation – and will require different strategies to allow them to regain normal levels again.

It’s now been nearly 2 months since I learned of my iron deficiency and have been supplementing as outlined above since. From struggling to make it thought the day without a nap and having given up on all attempts at speed, I now feel normal again and in my recent attempts at tempo and interval paces, I’ve hit the mark. I feel a million times better – but like there is still room to improve further. Mostly, it’s so exciting and encouraging to finally be on the upswing after so many months of struggling.

To deliciously healthy food and stronger faster running… Cheers,


Sarah J Cuff, RHN


Referenced Print Resources

1. Burke, Louise & Deakin, Vicki. Clinical Sports Nutrition, fourth edition. McGraw Hill Australia, 2010.

2. Daniels, Jack. Daniels’ Running Formula, third edition. Human Kinetics, 2014.

Comments 17

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  1. great read! last month I wasnt able to donate blood because my iron count is only 12 so I have to improve my eating habit by having iron rich food since I dont eat meat and good news my iron count pass and was able to donate the other day, Thanks for this

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  2. Excellent post Sarah! You’re low ferritin levels explains exactly why you’d been feeling the way you were. I’ll be keeping my fingers crossed for continued improvement for you.

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  3. Great post Sarah – a whole lot more informative than my physician who basically told me to eat a steak for breakfast, lunch and dinner!

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  4. Hi Sarah-
    I loved your post. I know it’s been a while since you posted. Did you get your ferritin re-checked? What were your new levels? I have been struggling to raise my levels through supplementation, and I am wondering what to do next.

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      Hi Kim… Thanks much! Ironically, I’m just in the process of getting re-tested again now – I was doing well in supplementing with enough iron when I was training for my 100 miler (and successfully finished it strong), but since then (October onwards) I’ve been terrible with supplementation (not taking near the 150mg minimum I should be) and can definitely tell I’m low again. The key with supplementing is ensuring you’re getting enough… And past that, the ‘right’ type, and even mixing a few different types, along with key dietary sources also. I’d start with ensuring your supplementing with enough to actually make a difference, and then go from there…

      1. my physician just recommended i take 325 mg/day of iron.. that seemed like a lot i thought? my levels just came back as 4.3…

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          Your physician appears to have deemed your case a ‘severe’ one – as I’ve definitely seen up to 300mg daily be recommended in severe cases. And looking at your numbers, I’m not surprised! I’m also assuming your physician has suggested you get your levels retested in a month or two – as that high dosage is not meant for the long term, simply to bring your levels back up as quickly as possible…

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  5. Hi Sarah! Just looking for an update to see if you’re still supplementing with the non-constipating for of iron and if you were ever retested. I’m severely anemic and would really love to hear how things have been going for you! Thanks and have a great day!

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      Hi Vonni… Oh yes, I was retested in March 2017 – hemoglobin up to 132 (from 125) and ferritin up to 25 (from 13). Around that time I switched to Bob’s Iron (a formula specific to Pure Pharmacy) which is made with similar non-constipating iron. I took 1 capsule daily – my alarm went off daily to remind me to take it so it was never missed. I took Bobs 150 (so 150mg iron daily). I was retested in March 2018, and hemoglobin now 139, and ferritin at 57. Clearly back into normal levels for high performance! And yesterday I ran a 3:34 marathon (only 4 minutes off my personal best) so I guess that says even in practice I’m really back 🙂

  6. Hi Sarah,

    I’ve been using Ferrous Sulfate for many years with good results, but really bad side effects.
    I’ve been wanting to try Bisglycinate, but wondering why you stopped using this form? Is it not working good anymore? Does it really have lower side effects at 150mg daily?

    Thank you

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