We plan to determine crew nutritional status before their missions, providing dietary counseling if deficiencies are noted. Food intake will again be monitored during the mission with real-time feedback from the ground. On mission completion, nutritional status will again be monitored to assess recovery in the post-flight period. Nutritional status assessment is critical for making sure that our crewmembers are healthy before, during and after long missions. A case in point is the assessment of Vitamin D levels.
Vitamin D is important for bone and calcium health on the ground and during space flight.
We get most of our vitamin D from dairy products and from sunlight exposure. Because the spacecrafts are heavily shielded to reduce astronauts' exposure to harmful radiation, exposure to the sun is limited on orbit. We have also learned from previous studies, that crewmembers' vitamin D levels are frequently decreased during the winter months in Russia, as compared to studies in sunny Houston. Star City, Russia, is about the latitude of Alaska and receives limited sunlight during winter. This can be significant as astronauts will complete some training in Russia.