|Posted on Jan 10, 2012 10:17:42 AM | Jessica Nimon | 1 Comments ||
In today’s blog, Dr. Sara Zwart shares with the readers of A Lab Aloft her thoughts and experiences as a scientist, including how sometimes data showing nothing can actually indicate something!
It’s always exciting to make new scientific discoveries. But though it may sound counter intuitive, sometimes it can be just as important to find nothing. When looking at research results, a lack of change can actually indicate that you have found something, which can lead to unanticipated, but amazing discoveries. This has happened twice in the past year at NASA’s Nutritional Biochemistry Laboratory as part of the Nutritional Status Assessment experiment, or Nutrition.
The goal of the Nutrition study is to understand what changes in an astronaut’s health while they live aboard the International Space Station. Improved knowledge in how humans react to living in space for long durations can help prepare NASA for future exploration to Mars, as well as help in understanding how well current efforts to counteract the negative effects of microgravity work. These countermeasures include exercise and a carefully planned diet, among other things.
For this study, astronauts collect blood and urine samples during flight, as well on the ground during the routine pre- and postflight testing. Before they fly, crew members train on how to take blood from each other or from themselves, and they also can practice collecting urine, which can be tricky in microgravity!
Ground training helps to prepare the crew for sample collection for the Nutritional Status Assessment experiment, or Nutrition. (NASA Image JSC2006E27274)
Upon return to Earth, crew member samples are analyzed for a broad range of chemicals and biochemicals, from nutrients to bone and muscle markers to hormones and other compounds. One of the nutrients we study is vitamin K, which is a crucial vitamin for blood clotting, and it also has an important role in maintaining bone health.
Early studies from the space station Mir provided evidence that vitamin K status may be lower during space flight, and researchers suggested that vitamin K should be investigated as a potential countermeasure for bone loss. Those early studies on Mir involved only one or two crew members, and a food system different from the one we use today on station.
A crew member works with test samples in the Human Research Facility 2 (HRF-2) Refrigerated Centrifuge as a part of the Nutritional Status Assessment (Nutrition) experiment in the Columbus laboratory of the International Space Station. (Credit: NASA)
For Nutrition, we measured vitamin K status from markers in the blood and urine in 15 station crew members at five different time points during their mission. We found no evidence for decrements in vitamin K status. In other words, vitamin K is still important for health, blood and bones, but there is no evidence that more would be better.
These types of “negative” findings are important. In this case, we learned that the current space food system is sufficient to maintain vitamin K status in astronauts. What’s further, at this time there is no basis for recommending vitamin K supplements to prevent bone loss that occurs during space flight.
A NASA astronaut places samples into the Minus Eighty Laboratory Freezer for ISS (MELFI-1).
Hormones can be measured in the crew’s blood and urine samples, providing valuable information on a number of the body’s systems. One hormone that we measured as part of the Nutrition study was testosterone. This is an important hormone in the body for building up and maintaining bone and muscle mass.
Some earlier studies suggested that there may be lower levels of testosterone in astronauts during space flight, which may contribute to some of the observed bone and muscle loss. As part of this study, we measured the blood levels of testosterone at five different time points during space flight to test this hypothesis. Again, 15 station crew members provided samples, however the analysis showed that no changes to testosterone occurred during flight.
Once more, these negative findings provided important information in working to understand how the human body adapts to microgravity exposure. This is especially true when we consider ways to counteract some of the known negative effects of weightlessness, including bone and muscle loss. By narrowing the causes of these concerns to human health in space, we get closer to identifying the root causes and providing significant countermeasures.
Sara Zwart, Ph.D., and her colleague Scott Smith, Ph.D., lead NASA’s Nutritional Biochemistry Lab at Johnson Space Center. The testosterone research discussed above was published in the Journal of Clinical Endocrinology and Metabolism (epub: doi:10.1210/jc.2011-2233), and the vitamin K work was published in the Journal of Bone and Mineral Research (26:948-54, 2011). In addition to ground-research studies, Zwart and Smith lead two space station experiments, Nutritional Status Assessment and Pro K, in which they investigate the roles of animal protein and potassium in mitigating bone loss.
Tags : Experiment Highlights, General, Guest Bloggers, ISS as a Laboratory, Results, Science, US Research