As astronaut is always to choose the food of his/her own choice . They have a tasting period of 15 days to eat and choose what foods he/she likes to eat in space. Of course there will be moderation by nutrition experts to ensure the astronaut is getting the recommended diet value of car/calories and so on.

[Kalpana Chawla][1], a vegetarian stayed in space for close to 31 days. There are a few other people who stayed much longer than this.

P.S.: Not every astronaut is going to be vegetarian but if they are going to Mars they should become [vegans][2]. The Mars living room test (underground test) for 1 year included only vegan foods.


[Food Options in Space][3]


  [1]: https://www.outlookindia.com/magazine/story/ragas-in-outer-space/204712
  [2]: https://inhabitat.com/nasa-astronauts-on-mars-mission-will-eat-100-vegan-menu/
  [3]: https://www.nasa.gov/audience/foreducators/stem-on-station/ditl_eating