Microgravity affects the heart's structure, changing the size of the ventricles, whereas space radiation can speed up the progression of atherosclerosis and even cause vascular calcification. This is why astronaut candidates undergo extensive cardiovascular testing. Advanced molecular technologies enable us to identify various health states in humans. Through detailed analyses of biological samples (blood, saliva, urine and stool), we have discovered that a significant portion of blood metabolites are unique byproducts of gut microbiome bacteria (the microorganisms that live in the human digestive system). Since the microbiome changes in space due to microgravity and altered diet, we anticipated corresponding changes in astronauts’ blood metabolites.

Over the past few years, we have developed one of the world’s largest databases for comparing cardiovascular patients and healthy individuals. Using mathematical models and machine learning, we have identified gut bacteria-mediated metabolic pathways with previously unknown links to the cardiovascular system.For this study, conducted in collaboration with Beilinson Hospital and the Weizmann Institute, we proposed to examine these same pathways in astronauts, as they have previously been studied only in people who stay on Earth.

Our research sought to create personalized metabolic maps for each astronaut based on microbiome and metabolite analysis from samples taken at various points before and after spaceflight. These maps will enable us to assess individual cardiovascular risk changes resulting from space travel, providing a comprehensive understanding of how staying in space impacts the cardiovascular system. We are grateful for the opportunity to partner with the Rakia mission and astronaut Eytan Stibbe on this groundbreaking and pioneering study. This experiment was not selected following the call for proposals in May 2021, but was approved and subsequently added by the scientific-technological committee in September 2021 due to its importance and contribution to comprehensive research at the hospital.This is one of the clinical studies conducted on the Ax-1 crew.

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