The science of iron
Iron is an essential mineral for health and for sports performance. It participates in oxygen
transport, energy production, and the activity of key enzymes involved in muscle
metabolism. Simply put: when iron is scarce, the body keeps functioning, but with
less ability to sustain effort, adapt to training, and recover well. 1,2,3
Iron deficiency is common in female athletes. The most recent systematic review
specific to this population indicates that up to 60% of female athletes may present
iron deficiency. 3 Iron-deficiency anemia is less common than isolated iron deficiency,
but it remains clinically relevant: in a recent cohort of female college athletes, the
The prevalence of iron deficiency anemia was 9,9%. 4
In the sports context this matters a lot, since while iron deficiency can affect
negatively on performance – especially in endurance disciplines –, correcting it can improve
aerobic variables in athletes with real deficiency. 3,5
Are female athletes really at greater risk?
The female athlete starts from a more delicate physiological situation for iron. To the losses
menstrual are added other factors inherent to the sport: increased demand, possible
gastrointestinal microhemorrhages, impact hemolysis in some disciplines, losses through sweat
and an absorption that does not always accompany, especially during periods of high load. 2,6
Furthermore, quite often another underlying problem appears: insufficient energy intake or a
availability of carbohydrates below what training requires. This not only penalizes the
performance; it can also worsen iron regulation. We know that hepcidin, a
hormone that reduces intestinal absorption and mobilization of iron, can increase after exercise
and hinder the replenishment of reserves, especially when physiological stress accumulates. 2,7
It is not necessary to reach anemia to notice the impact
The most recent systematic review in female athletes concludes that athletes with deficiency of
iron may see their endurance performance reduced, and that supplementation with prior deficiency is
it is associated with improvements especially in aerobic variables. 3
Translated into practice: if an athlete reports persistent fatigue, worse tolerance to effort,
sensation of 'empty legs,' slow recovery, or an unjustified drop in performance, is not advisable
attribute everything to the training volume, to stress, or to being 'out of shape.' Sometimes the problem lies in
some iron reserves that have been asking for help for a long time. 2,3,8
The competitive season matters too
In sports with long seasons or very tight schedules, iron can become a
even more sensitive factor. In a recent study on women's Australian football, the prevalence of
iron deficiency in the team was 47% at the beginning of the season and 54% at the end, reflecting a
deterioration of reserves throughout the competitive course. 9
In this context, ferritin is useful because it acts as a marker of iron stores. A
a decrease in ferritin during the season does not by itself imply an immediate drop in performance, but it can alert to a progressive worsening of iron status and an increased risk of
deficiency if not corrected in time. 2,9
Supplementation: useful, yes; automatic, no
Iron supplementation can be a very useful tool when there is a confirmed deficiency,
but it should not be considered as an automatic gesture nor as a bet 'just in case'. The
the most recent evidence in athletes shows that oral supplementation mainly improves
ferritin, and that its effects are clearer when the initial reserves are really low. In
change, the benefits on VO₂max or performance are not universal. 3,5
In practice, when an athlete has low iron stores, but not yet anemia, a
ferritin <35µg/L is one of the references used in sports to guide this situation. If it is
decide to supplement, a common guideline is to use oral iron for 8–12 weeks, often in
dose of 100 mg/day of elemental iron, although in women with digestive discomfort it can be opted for
on alternate days to improve tolerance. 10
It is also advisable to take care of how it is consumed: it is usually recommended to accompany it with a source of vitamin
C (strawberries, kiwi, oranges…) and separate it from calcium (milk, cheese, and dairy), coffee or tea, because they can
hinder its absorption. 10 This is important because classic oral iron is not always well tolerated:
nausea, constipation, and digestive discomfort are relatively common effects and can cause
The supplementation fails not due to a lack of effectiveness, but because the athlete is not able to maintain it.
enough time. 10
In this context, some newer formulations, such as liposomal iron, may be a
interesting alternative in women with poor digestive tolerance to classical oral iron, although its role
it must be understood above all from tolerance and not as a guaranteed superiority in all
cases.
The lactoferrin it has also gained interest as a possible adjuvant strategy, especially in
female athletes with poor tolerance to oral iron, in inflammatory contexts —such as schedules
very congested competitive or prolonged gastrointestinal processes—or during pregnancy.
Even so, the specific evidence in female athletes remains limited and, as of today, must
to be understood as a support and not as a substitute for conventional treatment when there is a deficit
confirmed. 10,11
So, what message should a female athlete take away?
That iron is not a minor detail nor just another supplement in the drawer. It is a factor that can
to directly condition how you train, how you recover, and how much you perform. And that, in women
athletes, the combination of menstruation, training load, low energy availability and
inflammatory contexts can turn an apparently small problem into a real limitation if
It is not detected in time. 2,3,6,8
Do you suspect an iron deficiency?
The important thing is not to become obsessed, but to know when it is worth taking a closer look. If you notice
unusual fatigue, worse training tolerance, slower recovery, sensation in the legs
empty or a drop in performance that does not match your workload, and in addition you live with factors of
risk such as heavy menstrual bleeding, tight schedule, low available energy, or problems
prolonged digestive issues, it is advisable not to normalize them.
In that case, the next step should not be to supplement on your own, but to consult with your
doctor or reference healthcare professional and request a blood test with iron profile to assess if it exists
really an iron deficiency.
In female athletes, not all fatigue is 'normal' and not every drop in performance can be fixed
pressing harder. Sometimes, the body does not need more demand, but more attention. Knowing how to identify
when iron may be lacking, confirming it well and acting with judgment can make the difference between
survive the season or truly perform within it.
Anna Teixidó Aguiló
Col No: MAD00674
Lactoferrin 200 (Natraferrin®) – 60 Capsules
Lactoferrin 200 from Crown Sport Nutrition is an advanced supplement that provides a minimum of 200 mg of lactoferrin per capsule, from the patented raw material Natraferrin® (derived from fresh milk). This product is designed for athletes of all disciplines, helping to optimize iron metabolism, accelerate muscle recovery, strengthen the immune system, reduce oxidative stress, and improve intestinal microbiota health. Its efficacy is supported by scientific studies published in high-impact journals. Lactose-free and with anti-doping certification from Informed Sport.
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Frequently asked questions about iron and female athletes
Why do female athletes have a higher risk of iron deficiency?
Female athletes have a higher risk of iron deficiency due to the combination of menstrual losses, increased metabolic demand from training, and possible additional losses associated with exercise, such as impact hemolysis, gastrointestinal microbleeds, or losses through sweat.
How does iron deficiency affect sports performance?
Iron is involved in oxygen transport and in cellular energy production. When iron stores are low, the body can experience fatigue, reduced exercise tolerance, poorer recovery, and a decrease in performance, especially in endurance sports.
What symptoms can indicate iron deficiency in a female athlete
Some signs that may suggest iron deficiency in athletes are persistent fatigue, a feeling of “empty legs,” slower recovery, worse tolerance to training, or a drop in performance that cannot be explained by training load.
What ferritin levels are considered low in athletes?
In the sports context, a ferritin level below 35 µg/L is usually used as a reference to indicate low iron stores, although the interpretation should always be carried out together with other analytical parameters and under medical supervision.
Is it advisable to take iron supplements without a blood test?
No. Iron supplementation should only be started when there is a confirmed deficiency through testing and under the supervision of a healthcare professional, since both iron deficiency and excess can have health consequences.
How to improve iron absorption when taken as a supplement?
To promote iron absorption, it is recommended to take it together with a source of vitamin C and to avoid consuming at the same time foods or drinks that hinder its absorption, such as dairy products, coffee, or tea.
Can iron deficiency appear without anemia?
Yes. It is possible to present iron deficiency without anemia, a relatively common situation in athletes. In these cases, iron stores are reduced, which can affect performance even when hemoglobin levels are still within normal ranges.
References
Christofi MD, et al. The effectiveness of oral bovine lactoferrin compared to iron supplementation in
patients with a low hemoglobin profile: A systematic review and meta-analysis of randomized clinical
trials. 2024.
National Institutes of Health, Office of Dietary Supplements. Iron – Health Professional Fact Sheet.
McCormick R, Moretti D, Peeling P, et al. A contemporary understanding of iron metabolism in active
premenopausal females. Sports Medicine – Open. 2022.
Pengelly M, Pumpa K, Pyne DB, Etxebarria N. Iron deficiency, supplementation, and sports
performance in female athletes: A systematic review. J Sport Health Sci. 2025;14:101009.
Inaba H, et al. Iron Deficiency Prevention and Dietary Habits Among Elite Female University Athletes.
2025.
Smid AN, Golja P, Hadzic V, et al. Effects of Oral Iron Supplementation on Blood Iron Status in
Athletes: A Systematic Review, Meta-Analysis and Meta-Regression of Randomized Controlled
Trials. Sports Medicine. 2024;54:1231-1247.
Australian Institute of Sport. How and when do I use it? Iron.
Ishibashi A, Maeda N, Kondo C, Goto K. Energy intake to meet total energy expenditure improves
iron deficiency and metabolic suppression in female long-distance runners: A case series study with
dietary intervention. 2025.
Dugan C, Peeling P, Davies A, et al. The relationship between menorrhagia, iron deficiency, and
anaemia in recreationally active females: An exploratory population based screening study. J Sci
Med Sport. 2024.
Gomes de Albuquerque A, O’Connor D, et al. Putting the Fe into Female Athletes: Insights into
Heightened Iron Status and Women’s Australian Football Performance—A Case Study. 2025.
Australian Institute of Sport. Iron: medical supplement guidance for athletes.
