Recent research findings from the International Space Station show there may be a link between nutrition, genetics and vision problems experienced by some astronauts.
Earlier reported findings from blood samples collected on the space station suggested chemical differences in astronauts with vision issues. Scientists conducted a follow-on study to identify genetic markers that help code the so-called “pathway of one-carbon metabolism.” The one-carbon pathway is a series of chemical reactions at the molecular level that involves several enzymes and requires B vitamins, including folate, vitamin B12 and vitamin B6. The body does not manufacture B vitamins and must obtain them through food.
Scientists in a number of disciplines and at several sites around the world supported the study and helped interpret the findings. Results of the team’s studies are in the January issue of The FASEB (Federation of American Societies for Experimental Biology) Journal.
“The results are striking,” said Scott Smith, Ph.D., nutritionist at NASA’s Johnson Space Center in Houston and co-author of the paper. “We’ve identified an associated genetic link in some astronauts who have the vision issues. We still don’t know the mechanism, or what is causing the vision issues, but being able to narrow down some of whom to study should help refine research and hopefully will speed finding the cause, and a way to treat, or ideally to prevent, these problems from happening. The results may have significant implications for NASA and future astronauts.”
Smith and Sara Zwart, Ph.D., lead author of the paper, direct the Nutritional Biochemistry Laboratory at NASA’s Johnson Space Center.
Results document two significant genetic differences, or polymorphisms. For one of these, everyone with the “minor form” of that polymorphism developed vision or eye issues to some degree. However, subjects who did not develop eye issues did not have that form of the polymorphism. For another polymorphism studied, all individuals (with one exception) with the “major” form of the polymorphism developed eye issues. Overall, the results suggest that astronauts with these genetic differences and lower B-vitamin status are at greater risk for vision and other ocular changes during long-duration spaceflight.
Additional work is needed to clarify and refine this information, to determine the mechanism causing these issues and then to develop a means to treat, or better yet, prevent these issues.
The first objective of additional studies will be to evaluate a broader set of genetic differences associated with this one-carbon metabolism pathway. The initial study was intentionally very limited, since this was NASA’s first look at individual genetic data. A broader evaluation is expected to provide a fuller understanding of differences.
The report also suggests there may be similarities between astronaut data and individuals with a clinical syndrome affecting 10 to 20 percent of women, known as polycystic ovary syndrome. Studying individuals with this syndrome may provide an analogous group to better understand vision and cardiovascular system effects, potentially advancing treatment or prevention for both astronauts and humans on Earth with this disease.
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