A new study published today in the Journal of Space Agriculture has concluded that eating fresh lettuce and leafy salads in space is a bad idea due to the high risk of food poisoning and other health hazards.
As NASA and other space agencies plan for longer human missions to Mars and beyond, finding ways to grow fresh produce in space has become a priority. Leafy greens like lettuce provide vital nutrients, add variety to space diets, and can boost morale. Over the past decade, astronauts have conducted experiments growing small amounts of lettuce on the International Space Station (ISS).
However, the cramped conditions and microgravity environment make contamination extremely difficult to control. Bacteria like E. coli and Salmonella spread much more easily in microgravity and are hard to kill.
According to Dr. Michelle Smith, the lead researcher:
“While leafy greens can successfully be grown in space, eating them raw poses too high of a health risk based on all the studies we have done to date. The microgravity conditions allow dangerous bacteria to get inside the leaves and form strong biofilms that are resistant to being washed off.”
New Research Findings
The research team conducted experiments growing romaine lettuce on the ISS and had astronauts sample it periodically. They also simulated ISS conditions on Earth.
Key findings include:
- E. coli infiltration reached Mediterranean lettuce leaves grown on the ISS in as little as 3 days
- Salmonella formed dense biofilms inside space-grown lettuce even after washing
- Antibiotic resistance genes increased in bacteria infecting space lettuce
- Food safety guidelines were extremely difficult for astronauts to follow properly
Table 1: Bacteria Counts in Lettuce Grown on ISS vs. Earth
cfu = colony forming units per gram
Dr. Smith summarized that “the situation is even worse than we thought”. Contamination occurred rapidly, and common sanitization methods didn’t eliminate the resilient space-adapted bacteria.
Consuming raw lettuce contaminated with hardy space-adapted pathogens would likely cause an intestinal infection. Symptoms could include:
- Digestive issues like diarrhea, vomiting, stomach pain
- Fever and dehydration
- More severe illness in immunocompromised astronauts
Such conditions could be difficult to manage on current space missions with limited medical capabilities. The spread of antibiotic-resistant “superbugs” also poses a grave concern for future missions.
Given the risks identified in this research, the authors make the following recommendations:
- Stop raw leafy vegetable consumption during spaceflight until better countermeasures become available
- Focus crop growth efforts on safer fruits and vegetables
- Improve diagnostics tests that detect microbial contamination
- Invest in sanitization techniques like new antimicrobial washes
- Cook or pickle greens to kill pathogens before consumption
Researcher John Lee added: “We may also need to genetically engineer space lettuce and other crops to make them more pathogen resistant”.
While the short-term verdict means no more fresh salads on space missions, the long term goal is still to enable astronauts to safely grow and eat fresh picked vegetables.
As missions extend further into space, the ability to produce some food on board becomes crucial. Dr. Michelle Smith cautions: “We can’t give up yet. More research into advanced food safety techniques tailored to space-grown crops will help us eventually get fresh salads back on the menu.”
Additional ISS experiments are slated to test new antimicrobial surface coatings and air treatments. Meanwhile, engineers continue working on greenhouse modules for sustainable crop production on Mars.
With innovative solutions, space agriculture may still become routine one day – including healthy, delicious salads. Just not yet.