Genetically modified lettuce created to keep astronauts’ bones from crumbling in space

DAVIS, Calif. — If you’re hoping to go to space one day, being a vegetable lover could help keep your body extra healthy. Scientists have developed genetically modified lettuce that could stop astronauts’ bones from weakening on their journey to Mars.

The crunchy plant with added hormones could protect space explorers’ skeletons from the side effects of living without gravity, according to a new study. Astronauts lose on average one percent of their bone mass for every month they spend in space, a condition known as osteopenia. This has thrown a wrench in the works for extended space missions and NASA’s plans to send humans to Mars in the next 20 years.

It would take astronauts around 10 months to reach the Red Planet, where they would remain for a year before making the long journey home. But now scientists at the University of California, Davis have come up with a simple solution via transgenic lettuce that astronauts could eat every day.

“Right now, astronauts on the International Space Station have certain exercise regimens to try to maintain bone mass,” says study co-author Kevin Yates, a graduate student in the UC Davis Department of Chemical Engineering, in a statement. “But they’re not typically on the International Space Station for more than six months.”

The researchers’ genetically modified the lettuce plants so they would contain a hormone that stimulates bone growth, known as human parathyroid hormone (PTH). A species of bacteria known as Agrobacterium tumefaciens was used to transfer the modified genes to the lettuce plants.

Astronauts have already shown they can grow lettuce on the International Space Station, despite its resource-limited environment.

“Astronauts can carry transgenic seeds, which are very tiny – you can have a few thousand seeds in a vial about the size of your thumb – and grow them just like regular lettuce,” says Dr. Somen Nandi, a co-author of the study. “They could use the plants to synthesise pharmaceuticals, such as PTH, on an as-required basis and then eat the plants.”

Genetically modified lettuce
Bone density loss is a problem for astronauts on long space flights, such as to Mars and back. Researchers at UC Davis are developing transgenic lettuce containing a treatment that astronauts could grow and consume during the voyage. Experimental lettuce growing in a greenhouse at UC Davis. (Credit: Kevin Yates/UC Davis)

They could also take medication containing PTH to limit the effects of zero gravity on their skeleton, but it requires daily injections. Transporting large quantities of these meds and syringes, as well as administering them during the mission, would also not be very convenient.

Lettuce plants with the modified gene, dubbed PTH-Fc, contained on average 10 to 12 milligrams of hormone. This means astronauts would need to eat about 380 grams, or about eight cups of lettuce every day to get enough protein. The researchers are now working to increase the amount of protein per plant so they are not faced with such a “big salad”.

“One thing we’re doing now is screening all of these transgenic lettuce lines to find the one with the highest PTH-Fc expression,” explains co-author Dr. Karen McDonald. “We’ve just looked at a few of them so far, and we observed that the average was 10-12 mg/kg, but we think we might be able to increase that further. The higher we can boost the expression, the smaller the amount of lettuce that needs to be consumed.”

The genetically modified plants could also help stave off osteoporosis in resource-limited areas here on Earth. Eating bone-growing greens will also improve astronauts’ diets which usually consist of canned and freeze-dried foods. But whether they can be grown on the International Space Station and still contain the same level of PTH remains to be seen.

The researchers have not tasted their creation as its safety is yet to be established, but they believe it will resemble regular lettuce. More research is therefore needed before the modified lettuce makes its way onto astronauts’ plates.

“I would be very surprised if by the time we send astronauts to Mars, plants aren’t being used to produce pharmaceuticals and other beneficial compounds,” adds Yates.

South West News Service writer Tom Campbell contributed to this report.

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