As a sports dietitian (CSSD), I talk about iron values, iron sources
and iron absorption, frequently. Adequate iron
levels, for all athletes, but especially for endurance athletes, are critical
to produce oxygen transporters, hemoglobin and myoglobin. As I describe to athletes, if you don’t have
enough iron, then you don’t have enough oxygen, and NO ONE wants to be in oxygen deficit when they
are trying to train and recover optimally.
For the science geeks, hemoglobin carries oxygen from the lungs to
bodily tissues and myoglobin is within the muscle cells patiently storing
oxygen for use when called upon during activity.
Athletes are particularly susceptible to iron deficiency anemia
due to low consumption of highly absorbable forms of iron, stress, overtraining
or even hemolysis, which is the breaking of blood cells when an athlete’s foot
hits the ground (impact forces) or during the constriction of blood vessels
during heavy training (1). The scary
news is that it is suggested that 20%-50% of female athletes and 4% to 50% of
male athletes have depleted iron stores, which suggests that many athletes
could benefit from an intervention that addresses this issue (2). Obviously, females are more susceptible than
men due to monthly menses and some sports are more at risk than others, namely
those in endurance sports such as swimming, running, rowing, triathlon, soccer
and basketball (3).
Additionally,
athletes who partake in a vegetarian or vegan lifestyle, have low overall
calorie consumption, low animal protein consumption, and those who have medication
interactions that lead to less iron absorption are also at higher risk. These athletes should be monitored more closely by health professionals and coaches for adverse
symptoms.
Symptoms
of Poor Iron Stores
- · Early exercise fatigue
- · Shortness of breath
- · Decreased training adaptations
- · Increased RPE (rate of perceived exertion)
- · Delayed wound healing
- · Poor condition of skin, hair or nails
- · Difficulty swallowing or sore tongue
Requesting blood work can seem daunting. Ideally, you will work with a professional,
such as a certified sports dietitian in conjunction with your physician, to
make sure that you not only order the correct markers of iron deficiency, but
to also help you interpret this information.
Some key things to note are that blood should be drawn 24 hours
post-training or during a recovery period to make sure it is as accurate as
possible.
The athlete should have blood
and urinary markers such as:
- · CBC (complete blood count)
- · Serum ferritin
- · Serum iron
- · Transferrin saturation
- · TIBC (total iron binding capacity)
- · Reticulocytes
- · Urine specific gravity (USG)
The intervention will depend on the results of this blood work and
the specific lifestyle factors of the athlete.
Iron supplementation should never be blindly administered, as it’s toxic
in high amounts or with specific conditions.
Athletes should note, there are two types of iron within food
sources, heme and non-heme, with heme iron being much readily absorbed by the
body. Heme is found in animal sources
such as lean beef, eggs, lean pork/ham, tuna, salmon and chicken breast. Non-heme iron is found in plant foods and its
absorption can be improved when consuming sources of vitamin C concurrently
(think strawberries, oranges, peppers or tomatoes). The problem is most people think spinach is
wonderful for iron, and while it’s a good non-heme source, certain types of
fiber (oxalates) inhibit the absorption of non-heme iron, so you’re going to be
hard pressed to make those sources a significant part of your diet and still
meet your needs.
Photo: StockSnap.io
The DRI (dietary reference intake) for iron is currently 18mg/day
for females ages 18-50 years, and 8mg/day for males. This is the amount needed for those who
already have adequate iron status, not for those who are found to be deficient
and require repletion. Specific populations
(i.e. pregnancy, lactation, vegetarians
and those out of the age ranges listed above) often require additional iron. Obtaining this amount won’t happen by
accident, so consumption of lean beef (3.5oz per serving) is an excellent option
to increase your daily iron and meet your protein needs. An easy salad is spinach, sirloin tip steak,
walnuts, cranberries, blue cheese and a raspberry or balsamic vinaigrette. I have it often and feel full and satisfied
from the fiber and protein, which helps me stay on track! Just the beef portion alone has 3.8mg, so
you’re headed toward your daily needs and it tastes wonderful as well.
Other sources of heme-iron include oysters (surprised on that one? I was!), eggs, lean pork/ham, tuna and salmon or chicken breast. I hope you enjoyed learning a bit more about your iron needs as an
athlete! Work with a sports RD to get
some specific advice and tailor your plan to meet your individualized needs!
1 (1) Selby,
G. B., & Eichner, E. R. (1986). Endurance swimming, intravascular
hemolysis, anemia, and iron depletion. The
American Journal of Medicine,81(5), 791-794.
doi:10.1016/0002-9343(86)90347-5
(2) Malczewska,
J., Raczynski, G., & Stupnicki, R. (2000). Iron Status in Female Endurance
Athletes and in Non-Athletes. International
Journal of Sport Nutrition and Exercise Metabolism,10(3), 260-276.
doi:10.1123/ijsnem.10.3.26
(3) Hinton,
P. S. (2014). Iron and the endurance athlete 1. Applied Physiology, Nutrition, and
Metabolism,39(9), 1012-1018. doi:10.1139/apnm-2014-0147
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