This is the final part of the series relating to iron, and will focus predominantly on how this effects athletes, when it’s time to supplement, symptoms to look out for and how you can keep yourself healthy. If you haven’t read parts I & II, covering how iron is absorbed, digested and regulated in the body, you can get part one here, and part two here.

Many people supplement blindly with an iron supplement, assuming that it is a silver bullet and flawless plan for treating and preventing anemia and iron deficiency. There are a number of drawbacks to using iron supplements, including the potential for gastric upset and the ease at which they can lead to toxicity levels. So what, then, can or should an athlete do to keep anemia at bay?

Just to reiterate the fact that there is a difference between iron deficiency and anemia, the former being a depletion in storage iron in the liver, spleen and bone marrow – resulting in depressed stores, decreases in decreased transport and an increase in TIBC, eventually leading to decreasing serum iron (see previous article if that doesn’t make sense). Iron deficiency starts to turn into anemia when ferritin levels drop below 12ug/L and your haemoglobin starts to fall out of range. Taking an iron supplement before this point will have no impact on performance, and one should wait until they are down near this 12ug/L range before supplementing with iron. Until you get to this stage, the best thing to do is to bolster your diet with foods rich in haem-iron and fortified products such as grains and cereals.

How can you tell if you are iron deficient or anemic? The simple and most effective answer is to get a blood test, it is a good idea to this annually anyway, or bi-annually if you are an elite athlete or in the at risk demographic (female endurance athlete). That really is the only definitive way to draw a distinction and place you in a distinct spot on the continuum of iron deficiency, but if your like me, you hate needles, and you won’t get a voluntary blood unless it is absolutely vital, what else can you do to keep tabs of your iron? There are a few physical and clinical signs you can look at, that may point you towards a conclusion.

Having pale skin, thinning hair, kyphosis (spoon shaped fingernails), pale conjunctiva (the red bit behind your eyelids) and noticing a decrease in training performance, by becoming short of breath much quicker and having a decreased exercise tolerance. Whilst this is useful info, it is important to note, that clinical and physical symptoms don’t usually precipitate until you are anemic or borderline. Alongside this, ferritin depression without drops in serum iron or haemoglobin, doesn’t actually impact on your ability to perform on the track, on the road or on the bike, as your oxygen transport capacity isn;t effected until your haemoglobin levels drop.

So, right now, what you can do is book a blood test (maybe wait until COVID has relaxed a tad), and ensure you get adequate iron intake, and pay special attention to the rich food sources and inhibitors, and start emphasizing this on a day to day basis. The biggest thing is to swap to wholegrain products over white options, getting your green veggies, pulses and nuts in on a day to day basis, consuming vitamin C with all these examples and if it’s possible, include lean red meat or offal 1-2 times per week, liver if you can hack it (I cannot).

If you would like some help with nailing your diet, click here to sign up for online coaching, and nail much more than optimizing your iron intake, or, if you just want a 60 minute session with a dietary analysis to get some quick and effective pointers, then click here to book a session in the athlete clinic, at a time that suits you, from the comfort of your own home!

I hope you enjoyed this three part series on iron, it is a vital nutrient for any athlete or sportsperson to optimize in their diet, and can very easily and quickly unravel an athlete’s sporting ambitions. I would love to hear your feedback, if you found it useful or helpful, and if you think others can benefit from it, please share it!

Happy trails,


What are the factors that drive this forward?

Knowing exactly how and why iron deficiency happens and slip slides into anemia is important in preventing it’s occurrence. Knowledge is power in a scenario like this.

Presuming you have read the last article outlining a background on iron requirements and digestion, you should now have some background understanding and context for this segment, if you haven’t read it, get it here.

Simply put, given that our body loses approximately 2mg (0.002g) of iron per day, and our body can store between 1-3g, you can do the math and see how not consuming any iron rich sources (or bioavailable sources) can lead to a gradual drop in iron stores. Just to clarify prior to getting into this article, there are two ways that anemia can occur (three, technically), the first one is anemia of chronic disease, which arises from chronic inflammation resulting in increased hepcidin expression, the second is genuine dietary insufficiency. Third is massive blood loss, as blood contains red blood cells and iron, if you have a heavy periods and shorter cycles, that increased bloodloss will result in drops in storage and iron levels, however, this is being classed as a technicality in my books, as female athletes have higher intake requirements as it stands, to counteract this.

The vast majority of people develop anemia from sub-optimal diets, elite athletes during more intense blocks of training may have inflammation related increases in hepcidin, which may have a degree of an effect, though this is unlikely to be as strong as an deficient diet, and the effect of hepcidin in this scenario is more transient in nature, whereas a poor diet is a constant. Let’s look at a number of measures that are looked at when we take iron status into account, and which help with diagnosis, and providing medical professionals and dietitians with a plan of action for intervention.

  1. Haemoglobin (Hb): The protein molecule that carries iron and oxygen around the body. This is the most used marker to test for anemia, low Hb signifies anemia presence. For adult females levels are typically 12-16g/dL, for men its 14-18g/dL.
  2. Haematocrit (Ht): A measure of the thickness of the blood, as red blood cells are large molcules, measured the volume of red blood cells against total blood volume. Female ranges normally 36-44%, whereas men are typically 40-50%. (Fun fact, levels above 50% may begin to be used as a cut off for blood doping in lieu of drug testing in the future).
  3. Ferritin: This is your storage iron, and can vary greatly, this will be the most telling read of iron deficiency, if stores are low but Hb is normal, an individual is iron deficient, but not anemic, and may not even feel any symptoms, ranges are 30-300ng/ml for men and 10-200ng/ml for women.
  4. MCV: Mean corpuscular volume, this is essentially a emasure of the average size and volume of your red blood cells, the normal range is 80-100fL, below this is called microcytic, in range is normocytic, above range is macrocytic. Most microcytic anaemia is caused by thalassemia or iron deficiency, resulting in smaller red blood cells, whereas macrocytic anemia is usually due to B vitamin deficiency resulting in irregularly large red blood cell production at DNA levels. Normocytic anemia means your blood cells are normal, but that you have very few of them, this can be caused by a range of diseases.
  5. TIBC & Transferrin saturase: Total iron-binding capacity is a measure is how much iron is bound to transferrin transporters, transferrin saturase is essentially another way to measure this. Normal ranges are 240-450mcd/dL for TIBS. The higher this number, the harder your body is working to absorb iron from your intestines.

If we think about it a little, it would make sense that pre-menopausal females are going to be at higher risk of iron deficiency, due to menstrual cycles, having a plant based diet due to lower bioavailability of the iron and a high degree of inhibitory phytates and oxalates, competed in a sport with chronic foot striking like running due to red blood cell rupturing and haemoglobin loss as a result. There a couple of factors that come into play also when it comes to food choice, pushing to lose weight and lower fat diets can tend to push individuals to avoid iron rich sources, social and cultural norms such as food trends and aversion can effect intakes (red meat aversion, vegan propaganda, judgement, religion, finance, personal preference to name a few). We must also acknowledge that adequate intakes of B-vitamins (folate and B12 specifically need to be taken), as they are co-factors in iron metabolism and DNA production, these are found in most animal products, poultry, dairy, grains and nuts, Celiac disease or IBD would be more likely to cause deficiency here than one’s actual dietary provision of said vitamins.

Other inhibitory factors to iron absorption include chronic usage of antacids and PPI medications, high dose divalent minerals (Calcium/Zinc/megnesium), tannins in teas and coffees (the amount of people who was down iron medication with these is super annoying…)

If you made it to now, you could see how this issue might progress forwards, having a poor diet with a lot of inhibitory factors, a poor awareness of where you can get iron from combined with inadequate overall dietary intakes. If we factor in a menstrual cycle and intensive training blocks, it really isn’t a surprise that so many female athletes are developing iron deficiency and anemia, with a good proportion of male athletes suffering too.

Up next, how can an athlete bolster themselves against iron deficiency, what to look out for and how not taking care of this can have disastrous effects on your performance!

Until next time,


This article is going to be the first on the topic of iron, how much we need, the roles it plays, how it’s used, digested and how our body’s maintain our iron stores, and how athletes are more prone to having lower iron stores. This will all result in a final breakdown of anemia or iron deficiency development, and it’s effects on athletic performance.

Iron is found in our diets in both plant and animal products, and it is found in it’s elemental (ferric) form. Human’s need to consume iron on a daily basis, as we can store between 1-3g in the body, in various forms, but we lose iron all the time via intestinal cell recycling (enterocytes), sweat, menstrual cycles and loss of skin cells. These losses account for approx. 1-2mg per day. Iron is used to carry oxugen around the blood and in the muscles, it is also used ot make red blood cells in bone marrow and is stored in the liver mainly as ferritin, this is your back up store, inadequate iron will result in poorer oxygen transport, saturation and breathing difficulties, it can also lead to extreme fatigue and cognitive impairment.

Although iron is found in both plant and animal products, animal sources are typically more bioavailable, as they contain heme iron (hemoglobin + myoglobin), which is absorbed better than the non-heme iron found in plant products, due in part to the high level of phytates found in plant foods, which impact on absorption. The absorption rate of heme iron is around 15-35%, whereas non-heme iron absorbs at rates of 2-20%. The varied rates of absorption are down to the bioavailability, transporter acitivity and inhibitors – Calcium, Zinc, Magnesium, Polyphenols and tannins (things that give tea & coffee colour) will all impede on iron absorption. It is recommended to get between 10-20mg per day, people following plant based diets should aim closer to 20mg, whereas standard diets can aim between 10-15mg. Unless an individual has iron deficinecy anemia, classified as low ferritin stores, haemoglobin, increased transferrin and TIBC, supplements are not recommended. Iron shouldn’t be taken in a prophylactic manner, to prevent deficiency, in certain cases, it is warranted, but this is not applicable to 99% of poeple reading this. Interestingly enough, your body actually down-regulates iron absorption rates when your stores are adequate or high, to keep it in or bring back to range.

It should be noted however, that consumption of vitamin C with iron rich foods, over rides any absorption inhibitors, as it is acidic, and helps activate the ascorbate ferrireductase transmembrane protein along cytochrome B, transforming the ferric iron into ferrous iron. Ferrous iron is then shuffled byt DMT1 into the intestinal cells (enterocyte). Heme iron has the distinct advantage of being absorbed directly by heme transporters, whereas the ferric iron must be reduced into ferrous iron first.

The vast majority of iron absorption occurs in the duodenum and the jejunum, these are both sections of the small intestine, and both are in close proximity to the stomach. This is likely due to the fact that iron requires an acidic environment (remember vitamin C a.k.a. ascorbic acid) to be better absorbed. Iron absorption is typically somewhere between 1-2mg per day, we do not absorb all of the iron from our diets, this is a good thing, as our bodies have no real excretion mechanism, it simply leaves our body when cells die, or with blood loss. Iron absorption is closely controlled by ferroportin and tranferrin, ferroportin is essentially the door that allows iron out of the intestinal cells into the blood, and transferrin is what carries it around the body to the liver, muscles or bone marrow. When iron levels get too high (there are reference ranges fro men and women), the body releases hepcidin, which blocks ferroportin, essentially trapping iron in intestinal cells, thus rendering us unable to absorb iron. Haemochromatosis is a genetic condition, where individuals have defective hepcidin, and the iron can build up to limitless levels. High levels of serum iron are neurotoxic, and cause a lot of redox and tissue damage, alongside providing a perfect growth medium for infectious bacteria.

That’s requirements and absorption in a nutshell, our bodies have an easier time absorbing heme iron sources, but it is still possible to get your needs via a plant based diet (harder to do), and there are things that will impact on our iron absorption, which is lower than you may have thought. Your body is very clever and resourceful at managing iron levels, and will exude a series of responses including changing ferroprotin, transferrin and intestinal ferric reductase activity, and hepcidin levels, in order to maintain tight control of our iron levels.*

*In a healthy person

Next up, how anemia and iron deficiency occurs, followed by a final article on anemia & athletes.