Ever wonder why exercise makes RLS worse, could this be why?

Can a Hard Workout Block Iron Absorption?

By

Alex Hutchinson.

Published

March 29, 2012

..

A lot of endurance athletes, particularly women, struggle with low iron. As a new study in the International Journal of Sport Nutrition and Exercise Metabolism explains:

The increased incidence of iron deficiency in female endurance athletes is thought to be the result of low dietary iron intake in this population, losses of iron in menstrual blood, sweat iron loss, and gastrointestinal blood loss.

But there's another possible reason, which is what this study (from researchers at Florida State) is all about. In brief: exercise produces inflammation (as evidenced by elevated levels of cytokines in the blood); inflammation causes increased production of hepcidin (a hormone produced in the liver); and hepcidin reduces iron levels in the blood.

To test the hypothesis that this sequence of events could contribute to iron problems in female athletes, the researchers had 12 endurance-trained women perform a one-hour run and a two-hour run, while they measured various blood parameters (cytokines, hepcidin, iron levels). Here's how hepcidin levels responded in the hours after the run:

As you might expect, a spike in inflammatory cytokines occurred right after the runs (so it preceded the spike in hepcidin). And there was a corresponding dip in serum iron levels around nine hours after the run (following the spike in hepcidin). All of this supports the sequence of events outlined in the hypothesis.

So what does this tell us? If you're supplementing iron, or consciously choosing iron-rich foods to keep your levels up (which is likely a good idea for many female athletes), you should try to time it so you're not taking the supplements in the six hours after a hard workout. Do it earlier or later in the day, so you're not fighting against this absorption-blocking effect.

One other note: when they broke down the results individually, five subjects had very large hepcidin responses, and seven had small or moderate responses. So the advice above probably doesn't matter for more than half of you, and might matter a lot for the rest. We don't know which half is which -- but if you suffer from perennially low iron levels, we can take an educated guess.

[Many thanks to Trent Stellingwerff of the Canadian Sport Centre Pacific for pointing this study out!]

[WideBody]

I see your report and raise you a more current one. I am reluctant to call myself an endurance athlete, however, I do stupid things several times a year that might qualify. I may not be highly trained, but I have done this all my life.

Effects of Macro- and Micro- Nutrients on Exercise Induced Hepcidin Response in Highly Trained Endurance Athletes

pubmed.ncbi.nlm.nih.gov/286...

The consumption of a CHO and protein-rich drink with or without the addition of vitamin D3 and K2 had no significant effects on hepcidin-25, IL-6, Hb, hematocrit, serum ferritin or serum iron in the present study. This may be due to a combination of the very high level of fitness of the subjects or the fact that they were fed a high CHO meal prior to each trial. Nevertheless, hepcidin and IL-6 response in the current study were characteristic of normal post-exercise inflammatory responses in trained individuals (Ward and Kaplan 2012; Wachsmuth et al. 2015).

Thus, regardless of the interventions used in the current study, individuals could still be susceptible to iron malabsorption post-exercise. Future research needs to revisit the effectiveness of peri-workout consumption, the constituents and dose of macro- and micro- nutrient protocols from both an acute and chronic standpoint.