Impact of diet on human nutrition, immune response, gut microbiome, and cognition in an isolated and confined mission environment

Abstract

Long-duration spaceflight impacts human physiology, including well documented immune system dysregulation. The space food system has the potential to serve as a countermeasure to maladaptive physiological changes during spaceflight. However, the relationship between dietary requirements, the food system, and spaceflight adaptation requires further investigation to adequately define countermeasures and prioritize resources on future spaceflight missions. We evaluated the impact of an enhanced spaceflight diet, with increased quantity and variety of fruits, vegetables, fish, and other foods rich in flavonoids and omega-3 fatty acids, compared to a standard spaceflight diet on multiple health and performance outcomes in 16 subjects over four 45-day closed chamber missions in the NASA Human Exploration Research Analog (HERA). Subjects consuming the enhanced spaceflight diet had lower cholesterol levels, lower stress (i.e. cortisol levels), better cognitive speed, accuracy, and attention, and a more stable microbiome and metatranscriptome than subjects consuming the standard diet. Although no substantial changes were observed in the immune response, there were also no immune challenges, such as illness or infection, so the full benefits of the diet may not have been apparent in these analog missions. These results indicate that a spaceflight diet rich in fruits, vegetables, and omega-3 fatty acids produces significant health and performance benefits even over short durations. Further investigation is required to fully develop dietary countermeasures to physiological decrements observed during spaceflight. These results will have implications for food resource prioritization on spaceflight missions.

Human gut microbiome and metabolite dynamics under simulated microgravity

“…This phylum is known to impact the gut microbiome of vulnerable patients with COVID-19 45 and other diseases, where its abundance and activity increase during harmful scenarios. 46 …”

Effects of isolation and confinement on gastrointestinal microbiota–a systematic review

“…A systematic review examining the human GI microbiota during long-term space missions confirms our results suggesting that space travel may lead to microbial dysbiosis and metabolic changes in the human gut, including a drop in alpha diversity ( 67 ). Similarly, a recent experimental study investigating the impact of an enhanced spaceflight diet on 16 subjects over a 45-day closed chamber mission found that subjects eating a standard diet demonstrated a decline in Shannon’s alpha biodiversity and richness during the mission, but recovered fully by the end of it ( 68 ). However, these effects are not evident and consistent across all participants of our review, as an increase in richness and biodiversity has been observed in some test persons, which is suspected in relation to an increased dietary fibre intake ( 54 ) or merely due to individual differences ( 40 ).…”

“…This finding is in line with more recent outcomes regarding maintaining GI microbiota eubiosis by probiotics ( 70 ). Furthermore, it is speculated that an enhanced spaceflight diet containing increased quantity and variety of fruits, vegetables, fish and other foods rich in flavonoids and omega-3 fatty acids, preserves community structure in the comparative analysis between pre- and in-mission time points ( 68 ). To potentially control or better mitigate negative effects better in the future, a diet-based therapy including higher contents of fibre could possibly provide an effective treatment ( 71 , 72 ).…”

Optimizing human performance in extreme environments through precision medicine: From spaceflight to high-performance operations on Earth

“…Vigilant attention was evaluated using the Psychomotor Vigilance Test (PVT), which was administered twice at baseline (pre-mission) and three times weekly over the 45-day mission. Those on the enhanced diet showed improved reaction speed ( p = 0.014), improved accuracy ( p = 0.022), and fewer attention lapses ( p = 0.0047) than those consuming the standard diet during the mission (Douglas et al, 2022 ). While PVT is not a direct measure of performance, it has been shown to be predictive of simulated spacecraft docking performance (Basner et al, 2020 ) and is correlated with rates of serious medical errors made by resident physicians (Rahman et al, 2021 ).…”