Crew members could taste the food before making their selections. As mentioned before, taste testing the food ahead of time could promote greater food satisfaction by getting crew members accustomed to the food. However, they should be reminded that in the spacecraft, they may experience digestive discomfort and they may therefore want to select foods that would calm their stomachs. After crew members make their food choices, a dietitian could evaluate their food choices and provide feedback. For instance, the dietitian could inform crew members that the items they selected are high in fiber or sodium and it would be advisable to choose some lower fiber or lower sodium options. The dietitian could also aid crew members in selecting a diet that contains main dishes, side dishes, and desserts – a structure that many study participants reported craving. Sample breakfasts, lunches, and dinners could be provided to guide crew members in making their food choices. This “pick your meals” approach may help increase food satisfaction while keeping the burden on aerospace companies low. However, this strategy should be tested prior to implementation because there is also the risk that providing crew members with such a vast number of food choices could lead them to become overwhelmed and less, not more, satisfied. Researchers have found that having numerous options can lead some people to experience regret and decreased satisfaction . In one experimental study having no choice in what one was served was shown to reduce anxiety and blood pressure more than being able to choose one’s meal components.
If the “pick your meals” approach resulted in lower, not higher, food satisfaction, a middle-ground strategy might involve providing crew members with 10 breakfast options and 20 lunch and dinner options,vertical vegetable tower and allowing them to taste test and select which meals they want. Another simple tactic that could increase food satisfaction would be to let crew members pack their favorite candies for dessert. Allowing crew members to choose their own food would enable them to make the calculated decision regarding whether they wanted the most calorie-dense food or whether they wanted less energy-dense food, which would result in fewer calories but perhaps higher food satisfaction. For instance, one participant who ate relatively few calories per day reported desiring lower energy density foods such as crackers, yogurt, and dehydrated vegetables and fruit. This participant also reported craving tuna, which is an item I did not include in the diet because the packaging on pouched tuna is higher mass and higher volume than the plastic over wrap on jerky. However, this individual had no need for 3,000 calories a day, and therefore no need for the most energy dense foods. If she were provided with the same sized food container as her fellows, she would be able to fit her preferred foods in that container , despite their lower energy density, while still meeting her nutritional needs. It is possible that, if taking this approach, some crew members may underestimate how much food they will want to eat. However, this would not likely be a problem in the Crew Transportation Vehicle, as food intake would likely be severely suppressed due to space motion sickness. Nearly half of all astronauts experience space motion sickness during the first eight to 72 hours of spaceflight, resulting in periodic bouts of projectile vomiting and avoidance of food . Food intake would also likely be suppressed due to being busy with more pressing tasks. Astronauts have recounted that, “At lift-off, astronauts knew the food system well, but eating was not high on the list of priorities during the hectic hours of getting to orbit and beginning on-orbit operations” .
Thus, if individuals were allowed to choose their own meals, they would likely have sufficient food in the Crew Transportation Vehicle. Allowing individuals to choose their preferred foods may also prevent food from going uneaten, which could prevent the flight of unnecessary mass and volume.This study had numerous methodological strengths. First, the study used a sample of commercial aerospace employees who were interested in participating in future commercial spaceflight opportunities and who may represent the future of commercial astronauts. Consequently, they were an ideal sample for a study of commercial space food. The study design was also novel; although numerous “space food taste tests” and nutritional studies of astronauts have been conducted , and although researchers have investigated the health impact of eating at commercial restaurants and of eating ready-made meals , researchers had not previously investigated the psychological and physical health consequences of eating commercially prepackaged ready-to-eat food for several days. Hence, this was the first evaluation of the psychological and physical impact of eating commercial, ready-to-eat “space food” for the length of time that astronauts could be in the Crew Transportation Vehicle. However, the study was not without limitations. One limitation is that the consequences of eating the experimental diet cannot be directly compared to the consequences of eating NASA space food. However, NASA space food is not commercially available, and therefore it was not possible to obtain NASA space food for use in this study. Furthermore, many of the individuals who will participate in commercial spaceflight will be civilians, rather than NASA employees, and such civilians would not have the option of eating NASA-made food. Consequently, this study’s comparison of commercial, ready-to-eat food to eating as normal was the best possible method for investigating the study’s aims. Another limitation of this study is that participants were permitted caffeinated coffee and tea throughout the experimental condition, whereas astronauts will not have access to these caffeinated drinks while in the Crew Transportation Vehicle.
However, asking participants to refrain from consuming caffeine would have increased the burden of participating in the study. Additionally, because this study used a parallel crossover design, in which participants served as their own controls, it is likely that participants’ caffeine consumption was similar in both the experimental and control conditions. This similar caffeine consumption would effectively cancel out the possible effect of caffeine on study outcomes. Furthermore, astronauts in the Crew Transportation Vehicle will likely have access to caffeine or alertness-enhancing medications – both of which are used on the ISS – which could be used in the event that enhanced or extended alertness is required. Consequently, allowing caffeinated drinks in this study should not have greatly impaired the generalizability of the results. Another limitation is that participants in the experimental condition may have altered the timing of their meals, ate in a different location, or ate with different people than usual. These factors could have influenced participant outcomes in unknown ways. However, forcing participants to eat at exactly the same times as usual was not feasible. For instance, some participants ate meals at different times every day. Forcing participants to eat in certain ways or to eat certain amounts could have also led to resistance, as was seen when researchers attempted to get all astronauts on a Skylab flight to eat the same amount . Consequently,vertical farm tower participants were encouraged, rather than required, to eat with the same people, at the same time, and in the same location as usual. Another limitation of this study is the small sample size. However, the study used a parallel crossover design, which is a study design that can obtain greater power with smaller sample sizes, as compared to a parallel-group design . The study also used repeated measures, with most of the measures being completed eight times throughout the study. These repeated measures further increased the study’s power . Additionally, the study used continuous, as opposed to binomial, dependent variables, which also increased power. Finally, I conducted a priori power analyses, which indicated a sample size of six would be sufficient for the effect magnitudes I aimed to detect, and I ended up with a sample size of seven. Consequently, the sample size of this study was sufficient to detect any meaningful differences between the two conditions. Another limitation of this study is that it took place on Earth in normal-gravity conditions, and therefore it is not a perfect predictor of how astronauts will eat while in the Crew Transportation Vehicle. For instance, astronauts may experience space motion sickness, gastrointestinal discomfort, a dulled sense of taste, and busy schedules . It is not clear if astronauts under these conditions would exhibit the same food preferences, such as the preference for an entrée, a side, and a dessert. However, there is no perfect way to simulate spaceflight on Earth. Bed rest and closed habitats are common ways to attempt simulation, but although bed rest can simulate some of the effects of microgravity, it cannot simulate the social situations. And although closed habitats can simulate the social situations, they cannot simulate microgravity. In the study described here, I attempted to conduct an analog-type study by using a sample of commercial aerospace employees with high workloads. Although this sample and the environment were not perfect analogs for flights in the Crew Transportation Vehicle, they were the most representative sample that could be obtained for this study.
A final limitation of this study is that it did not include a measure of body composition that could separately assess fat mass, lean mass, and water mass. Given that astronauts tend to lose weight during spaceflight, and that the participants in this study lost weight, it is important to get a better measure of how body mass changes during the course of eating commercial space food. Future studies of commercial space food diets should assess weight change using DXA scans or other measures that accurately assess body composition. This study was the first to evaluate a possible commercial space food diet made entirely of commercial, ready-to-eat food. Findings from this study showed that the diet, when eaten by commercial aerospace employees, did not lead to significant changes in caloric intake, mood, self-rated health, perceived stress, perceived social disconnection, or sleep. However, when eating the ready-to-eat food, participants did lose weight, possibly due to consuming less water. The commercial, ready-to-eat diet was also rated by participants as being slightly less hedonically rewarding and participants reported being slightly less satisfied with the variety of the food. However, as hypothesized, the commercial, ready-to-eat food was rated within two points of the control food on the 9-point Hedonic Scale, as well as on the scale assessing satisfaction with variety. It should also be noted that half of the commercial, ready-to-eat food items were rated 6.0 or better, which is NASA’s cut-off for acceptability. When eating the commercial, ready-to-eat food, participants desired fewer sweets and, in post-study qualitative interviews, expressed the desire for more meats, fruits, vegetables, and real desserts, so as to provide the sensation of receiving a “real” meal with an entrée, a side, and a dessert. Participants also provided suggestions for how the diet could be improved. These suggestions should be incorporated prior to flying the diet in the Crew Transportation Vehicle. Research comparing a standard diet, such as the one used in this study, to personalized diets chosen by crew members should also be conducted, as allowing crew members to choose their own food may further increase food satisfaction. Providing personalized diets may also reduce the likelihood of flying unnecessary mass in the form of uneaten food. Although the aim of this study was to evaluate a diet for use by humans in outer space, the findings have implications for humans on Earth, as well. The consumption of commercial, ready-to-eat food has become commonplace, if not the norm, for many individuals in developed nations. Ready-to-eat food makes up a majority of U.S. household consumer packaged goods purchases, with 61% of the calories purchased coming from highly processed food that is “no longer recognizable as their original plant/animal source” . The consumption of ready-to-eat or ready-prepared meals is especially common among individuals of lower socioeconomic status due to work constraints and the perceived costliness of healthy food . It is well known that consuming fresh fruits and vegetables is beneficial but what if these fruits and vegetables have been formed into ready-to-eat products? For instance, many of the foods included in the experimental diet contained dried fruit, nuts, flax seeds, and organic rolled oats. Are these ready-to-eat products healthy because they contain wholesome foods, or unhealthy, because they are processed to the point where the food sources are no longer recognizable?