B-Complex: A Nutraceutical SANS Countermeasure

In this project, the investigators propose to test effectiveness of a daily nutraceutical supplement containing bioactive B vitamins to mitigate optic disc edema in astronauts. The proposed countermeasure is intended to maximize functioning of the one-carbon metabolic pathway to provide enough substrate and cofactors to overcome any genetic differences that may impact the efficiency of enzyme function. By optimizing the pathway, this will 1) optimize endothelial function by increasing eNOS coupling and nitric oxide synthesis and 2) optimize collagen firmness and elasticity in the sclera and lamina cribrosa, and 3) minimize changes in total retinal thickness during and after flight. The protocol includes assessments of ocular health and function, along with determinants of vascular endothelial function, advanced glycation end products, and nutritional status and one carbon biochemistry. These additional measures will be critical for the further definition of the causes of optic disc edema in some astronauts after long-duration space flight, and in understanding the effect of the countermeasure. Finally, the supplemented subjects in this study will be compared against total retinal thickness data from previously flown astronauts known to have not taken supplements during their missions.