Lunch on Mars, anyone?
MED nutrition consultant focuses on astronauts' fitness and food
On January 14, President Bush proposed that NASA make a return trip to the moon by 2020, and eventually send astronauts to Mars and beyond. What will astronauts eat on these long flights in space, and how will they stay fit?
At present, with a stepped-up focus on studying how humans can live off the Earth for long periods, nutrition experts such as Caroline Apovian are helping establish healthful and tasty diets for astronauts on prolonged missions, as well as developing a minimal set of clinical measurements and evaluations to assess crew health and fitness.
NASA has asked Apovian, a MED associate professor of medicine, to participate in developing a Clinical Status Evaluation (CSE) program with the agency's Nutritional Biochemistry Division. Last October, she joined nutrition professionals from across the country in a two-day workshop at the Johnson Space Center in Houston to review existing knowledge of diet and spaceflight and make recommendations on how to meet the nutritional needs of crew members.
“The CSE is being developed as part of a continuing effort to ensure the health and well-being of astronauts during space travel,” says Apovian, director of the Nutrition and Metabolic Support Services at Boston Medical Center.
Medical issues in space exploration include decreased bone density and muscle mass. Scientists blame these problems on weightlessness and stress, along with vitamin D deficiency. The body usually makes vitamin D when the skin is exposed to sunlight, but spacecraft are shielded to protect astronauts from harmful radiation. Because current space foods don't provide enough of the vitamin, supplements are often included.
“If astronauts lose weight and muscle on long space flights,” says Apovian, “there may be risks, and these risks are acceptable if there is a small impact to the mission. But the risks are unacceptable if there is an impact that leads to many mission objectives lost, or even an aborted mission. This could mean serious injury to crew, or even death.” Such a problem might occur, for example, if an astronaut is so incapacitated by bone and muscle loss that he or she doesn't have the strength to get out of the capsule after landing, or fractures a bone in the process.
Despite diets that are designed to supply each crew member with 100 percent of the daily requirement of vitamins and minerals, astronauts usually lose weight during flights. “Their appetite isn't as strong in space, and we don't really understand all the reasons,” says Apovian. “They just don't eat as much, and this is a concern.”
Part of the problem may be the astronauts' schedule and time limitations, which tempt them to substitute snacks for meals, leading to nutrient deficiencies. In addition, more than half experience space motion sickness, which curbs their desire to eat.
Apovian says that another factor may be the bland menu. Meals in space have come a long way since the Mercury flights 40 years ago, when freeze-dried powders and semiliquids packaged in aluminum tubes were the standard fare. Rehydratable foods now include chicken consommé and cream of mushroom soup, casseroles of macaroni and cheese or chicken and rice, dishes such as salmon with broccoli au gratin, and breakfasts such as scrambled eggs and cereals. Nonetheless, the meals are hardly gourmet feasts.
“They get tired of freeze-dried foods, and I don't blame them,” says Apovian. Astronauts say it tastes like camping food. Fresh food is far more preferable, but it needs to be kept cold. “Spacecraft usually don't include much refrigerator space,” she says, “so it's difficult to include food that is more palatable.” Although there was a refrigerator on Skylab, and the International Space Station has one, refrigeration hasn't been a priority in NASA's shuttle program. But it might be on longer flights. “When there was a refrigerator on one of the shuttle missions,” Apovian says, “the astronauts managed not to lose as much weight as on other missions, so refrigeration may become an issue.”
Apovian says the nutritionists participating in the CSE program will convene again in the early spring. No U.S. astronaut has ever stayed in space for longer than 196 days — and because it would take more than a year to get to Mars and back, in the future meals with multiyear shelf lives will be needed, so nutrition research will continue to play a crucial role in space exploration.
Prolonged periods of reduced gravity or microgravity could have profound effects on the health of space crews. “Needless to say,” Apovian says, “we need to keep the astronauts in good physical condition.”