Effects of Iron Deficiency in Female Runners (A Guest Post)

By Ana Breit

When people think of nutritional deficiencies, they probably picture women with goiters due to lack of iodine or other newsworthy examples. In reality, the most common nutritional deficiency in the United States is iron deficiency. Iron Deficiency (ID) is especially common in endurance athletes, especially female athletes.


Start of 2013 Roy Griak Invitational Cross Country Meet at
the University of Minnesota. Photo courtesy of Jennifer Larson.

Iron is the metal in humans that allows oxygen to be carried in our bloodstream to all of our other organs. Without enough iron, less oxygen is taken to the muscles and other organs that need it. People with anemia (iron deficiency) may experience fatigue, weakness, and dizziness. Scientists Irena Auersperger, from the University of Ljubljana in Slovenia, Branko Skof and Bojan Leskosek, both from the University Medical Centre in Ljubljana, Slovenia, Ales Jerin, from the University Clinic Golnik in Golnik, Slovenia, and finally Mitja Lainscak, from Campus Virchow-Klinikum in Berlin, Germany asked how iron levels affect performance levels in female runners and whether or not intensified training impacts various iron parameters.

Fourteen moderately active women were chosen to participate in the study. In order to be enrolled they had to have regular menstrual cycles, eat animal products on a regular basis, and not be taking forms of medication except birth control. Each woman was put into one of two groups based on her ferritin levels. (Ferritin is a protein that stores iron). Anyone with ferritin levels greater than 20 micrograms per liter was put in the Normal group (for normal iron stores). Anyone with ferritin less than or at 20 micrograms per liter was put into the Depleted group (for depleted iron stores).

The study took place during a training period leading up to the International Ljubljana Marathon. During the eight week training period, runners had routine tests consisting of a 2400 meter (1.5 miles) time trial on a standard 400 meter outdoor track. Blood samples were taken at three different times: once before the eight week training period, once after the training period, and once more ten days after the marathon. These measurement times will be referred to as baseline, training, and recovery, respectively. Height, weight, and body fat percentage were measured during baseline and at recovery. Each woman then ran on a treadmill so researchers could measure her maximum speed, maximum oxygen consumption (VO2 max), and heart rate. Blood samples were taken at baseline, training, and recovery points to measure various blood parameters and iron parameters.

Both Normal and Depleted groups had similar body measurements, VO2 max, and heart rates. Both groups had improvements in their endurance measurements, however, only the Normal group had endurance improvements that could be documented as significant while the Iron Deficient group’s endurance improvements were less. By the end of the experiment, most of the runners were anemic. Both groups experienced a decrease in iron levels during the training and recovery periods compared with the baseline levels. Overall, both groups’ iron levels decreased in all areas during the training phase, even though they were both getting stronger and faster. The group that started out with lower iron levels did not show as great of an improvement as the group with the normal iron levels at baseline. Even after the 10 day recovery period, iron level parameters were still considered low. With this data, the researchers agree that Iron Deficiency decreases performance levels of female athletes.

Even though most people consider running to be a very healthy pastime, it can have undesired negative effects as well. All endurance athletes, especially female athletes, should have their iron levels checked regularly, and should make a conscious effort to incorporate iron into their hopefully already healthy diet by eating any enriched grains and a healthy amount of red meat. With consent of a physician, iron supplements can also be a good way to keep iron levels in check.

Bibliography

Auersperger I, Škof B, Leskošek B, Knap B, Jerin A, & Lainscak M (2013). Exercise-induced changes in iron status and hepcidin response in female runners. PloS one, 8 (3) PMID: 23472137

Science Beat: Round 4

It’s exam time again, and some of us need to study and let off some steam. These sciency music videos are just the ticket!

Biochemistry:

Cellular Biology:

Neuroscience:

Vote for your favorite in the comments section below and check out other sciency song battles at Science Beat, Science Beat: Round 2, Science Beat: Round 3, Science Song Playlist, The Science Life, Scientist Swagger and Battle of The Grad Programs! And if you feel so inspired, make a video of your own, upload it on YouTube and send me a link to include in a future battle!

The Beginnings of Jurassic Park: Dinosaur Blood Discovered? (A Guest Post)

By Samantha Vold

The classic tale of Jurassic Park, where dinosaurs once again walked the earth has tickled the fancy of many a reader. Dinosaur DNA preserved in a fossilized mosquito was used to bring these giants back to life. But in real life, it was previously thought that there was no possible way for organic materials to be preserved, that they often degraded within 1 million years if not rapidly attacked by bacteria and other organisms specialized in decomposition. Skin and other soft tissues, such as blood vessels, would never withstand the test of time. Or would they…?


T. rex skeleton at Palais de la découverte. Image by David Monniaux at Wikimedia

In 1992, Mary Schweitzer was staring through a microscope at a thin slice of fossilized bone, but this bone had something unusual. There were small red disks located in this tissue and each had a small dark circle in the middle resembling a cell nucleus, the command center of the cell. And these little disks very much resembled the red blood cells of reptiles, birds, and other modern-day vertebrates (excluding mammals). But it wasn’t possible, was it? These cells came from a 67 million-year old T. rex. And it was commonly accepted that organic material never lasted that long.


Comparison of red blood cells. Image by John Alan Elson at Wikimedia

This opened a huge controversy in the scientific community, but Schweitzer persisted. She consulted with her mentor, Jack Horner, a leading scientist in the paleontology field, and he told her to prove to him that they weren’t red blood cells. Schweitzer took the challenge and began to run some tests.

The first clue to these mysterious scarlet-colored cells potentially being red blood cells was the fact that they were located within blood vessel channels of the dense bone that were not filled with mineral deposits. And these microscopic structures only appeared inside the vessel channels, as would be true of blood cells.

Schweitzer then began to focus on the chemical composition of these puzzling structures. Tests showed that these “little red round things” were rich in iron, and that the iron was specific to them. Iron is important in red blood cells as it helps to transport oxygen throughout the body. And the elemental make-up of these little red round things differed greatly from the surrounding bone and sediment around them.

The next test was looking for heme, a small iron-containing molecule that gives blood its characteristic color and allows hemoglobin proteins to transport oxygen throughout the body. Schweitzer tested for this through spectroscopy tests, which measure the light that a given material emits, absorbs, and scatters. Her results from these tests were consistent with what one would find in heme, suggesting that this molecule existed in the dinosaur bone she was analyzing.

Schweitzer then conducted a few immunology tests to see if she indeed had found hemoglobin in these ancient bones. Antibodies are produced when the body detects a foreign substance that could potentially be harmful. Extracts from the dinosaur bone were injected into mice to see if antibodies were produced to ward against this new organic compound. When these antibodies were then exposed to hemoglobin from turkeys and rats, they bound to the hemoglobin. This suggested that the extracts that caused an antibody response in the mice included hemoglobin. This in turn suggested the T. rex bone contained hemoglobin, or something very similar.

Through years of research, Schweitzer has shown that what was once believed to be impossible is indeed true. Soft tissues, blood cells, and proteins can withstand the test of time. This process is possibly done through iron binding to amino acids (the molecules that make up proteins) and thereby preserve them. Research is advancing in this area, but as of yet, no DNA has been found to bring Jurassic Park to life. But for the avid believer, don’t get up hope yet. Perhaps one day we truly could walk amongst dinosaurs.


References:

Fields, Helen. (May 2006). Dinosaur Shocker. Smithsonian. Smithsonian Magazine.

Pappas, Stephanie. (13 Nov. 2013). Mysteriously Intact T. Rex Tissue Finally Explained : DNews. DNews. Live Science.

Schweitzer, M. (2010). Blood from Stone Scientific American, 303 (6), 62-69 DOI: 10.1038/scientificamerican1210-62

Melatonin is Not a Magic Pill

European hamsters showed us that there is more to
annual body rhythms than melatonin. Image by
Agnieszka Szeląg at Wikimedia Commons.

Many animals undergo seasonal physiological changes in order to ensure that their babies are born during a time of more abundant food and milder weather and to help their bodies prepare for harsh winter conditions. In order to precisely time these physiological changes with the seasons, most animals have evolved to respond to the most reliable marker for time of year, photoperiod (the number of hours of daylight in a 24-hour period).

In mammals, the hormone melatonin, produced by the pineal gland in the brain, is thought to be essential in this process of annual body rhythms. New research finds that the real story is much more complicated. To learn more about this, read the full article at Accumulating Glitches.


Monecke, S., Sage-Ciocca, D., Wollnik, F., & Pevet, P. (2013). Photoperiod Can Entrain Circannual Rhythms in Pinealectomized European Hamsters Journal of Biological Rhythms, 28 (4), 278-290 DOI: 10.1177/0748730413498561