Written by Jessica Patella, ND. Iron supplementation improved exercise performance demonstrated by increasing O2 intake lowering heart rate on average by -4.05beats/min in athletic women.

Iron deficiency and iron deficiency anemia are common in reproductive females due to menstrual blood loss (1).  Female athletes are at an even greater risk due to minor inflammation and micro-bleeding caused by vigorous training (1, 2). Approximately 496 million non-pregnant women are anemic worldwide and it is estimated 50% of these cases are due to iron deficiency (3). Due to the large number of women affected, the World Health Organization recommends iron supplementation to all women in populations where at least 20% of the population is anemic. Recent research on this topic has found that iron supplementation in women can improve physical performance, especially in female athletes (1).

Researchers recently reviewed and analyzed 22 different research studies on the topic of iron supplementation and physical performance (1). The studies were combined to analyze a larger group, which included a total of 911 participants, 464 of which were randomly assigned to take iron supplementation (doses ranged from 10 mg per day to 325mg per day of elemental iron (FeSO4 or ferric ammonium citrate) and 447 were in control groups (1).

Physical performance was measured by VO2 max and heart rates. VO2 max is a measure of the maximal ability of an individual to use oxygen during exercise; the greater the VO2max, the better. The VO2 max is the maximum amount of oxygen a person can take in, despite an increased workload.

Overall, iron supplementation improved both maximal exercise performance demonstrated by VO2max and submaximal exercise performance demonstrated by a lower heart rate (VO2max mean difference: 2.35mL/(kg x min), 95% CI 0.82,3.88, P=0.003; heart rate mean difference: -4.05beats/min, 95%CI-7.25,-0.85, P=0.01). It is important to note this improvement was observed only in women who trained athletically or were already iron deficient. There was no significant improvement in women without iron deficiency anemia or who did not train (1).

The researchers hypothesized that because iron can improve the oxygen-carrying ability of the red blood cells and because the body requires more oxygen required during exercise, this could explain why iron supplementation helped improve physical performance in women who trained (1). Iron is also lost in sweat, which could also explain the greater need in athletes (1,4).

In conclusion, daily iron supplementation significantly improved maximal and submaximal exercise performance in women of reproductive age (1).

Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health.  She earned her ND from Southwest College of Naturopathic Medicine in Tempe, AZ, and is a member of the North Carolina Association of Naturopathic Physicians.  Visit her website at  www.awarenesswellness.com.

Source: Pasricha, Sant-Rayn, et al. “Iron supplementation benefits physical performance in women of reproductive age: a systematic review and meta-analysis.” The Journal of nutrition 144.6 (2014): 906-914.

© 2014 American Society for Nutrition.

Posted May 23, 2014.

References:

  1. Pasricha S-R, et al.  Iron Supplementation Benefits Physical Performance in Women of Reproductive Age: A Systematic Review and Meta-Analysis. J Nutr. doi: 10.3945/jn.113.189589
  2. Peeling P, et al.  Athletic induced iron deficiency: new insights into the role of inflammation, cytokines and hormones.  Eur J Appl Physiol. 2008:103:381-91.
  3. Stevens GA, et al.  Global, regional and national trends in haemoglobn concentration and prevalence of total and severe anaemia in children and pregnant and non-pregnant women for 1995-2011: a systemic analysis of population-representative data. Lancet Glob Health. 2013;1:e16-25.
  4. Rodriguez NR, et al.  American College of Sports Medicine position stand.  Nutrition and athletic performance.  Med Sci Sports Exerc. 2009;41:709-31.