Quirks & Quarks

Genetically modified space salad could help prevent astronauts' bone loss, researchers say

Bob McDonald's blog: Scientists have developed a transgenic lettuce that produces a bone stimulating hormone. They say it could help prevent bone loss in astronauts.

Bob McDonald's blog: specially grown lettuce could help astronauts as well as people with osteoporosis

NASA astronauts Scott Kelly and Kjell Lindgren on the International Space Station snack on some lettuce grown in space in 2015. Now researchers have genetically modified lettuce to produce human parathyroid hormone, with the hope that astronauts could grow it and eat it to prevent bone loss in space. (NASA)

Scientists have developed a genetically modified lettuce that produces a bone-stimulating hormone that they say could help prevent bone loss in astronauts.

Floating around like Peter Pan inside the International Space Station is surely a wonderful experience, but it comes at a cost, especially for astronauts who spend long periods in the microgravity environment of space. Without the constant downward pull of gravity, their bones lose calcium, becoming less dense and more brittle.

The condition is known as osteopenia, which continues to cause problems when they return to Earth's gravity. In a way, it's like an accelerated version of osteoporosis.

To minimize this bone loss, astronauts exercise two hours every day using specialized equipment designed to put stress on the bones and stimulate growth.

But while this has dramatically reduced the problem during long-term missions on the space station, it is not enough. Astronauts still lose about one per cent of their bone mineral density every month they spend in space, even with thousands of research projects dedicated to understanding how to prevent it.

A future trip to Mars and back could take up to three years to complete, so bone loss would be a very serious issue. 

This lettuce produces a bone-stimulating hormone that could help stave off bone loss in space and on Earth. (Kevin Yates/American Chemical Society)

But researchers at the University of California, Davis have developed one potential remedy for this. They have genetically modified lettuce to produce human parathyroid hormone (PTH) which is known to promote bone growth.  It might also be helpful for people with osteoporosis on Earth.

They presented this new lettuce this week at the spring meeting of the American Chemical Society (ACS)

There are a number of potential advantages to this medicated salad. Astronauts could grow and eat their medicine rather than having to bring, store and inject the pharmaceutical version of PTH. 

And as we've talked about on Quirks & Quarks, NASA has already experimented with having astronauts grow salad in microgravity on the International Space Station. So all they would need is a package of the transgenic seeds and they could grow this new type of lettuce on the voyage.

"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," Somen Nandi, one of the researchers on the team, said in an ACS press release.

Lettuce also produces a lot of seeds once it matures, so there would be no problem of supply over the long haul.

There are still a few issues to resolve. So far, this laboratory lettuce doesn't produce much of the hormone in its tissues. The researchers said astronauts would have to eat eight cups of the vegetable every day to get the proper dose, which is a lot of salad to grow and to eat. The researchers hope they can increase the drug content so it won't be such a mouthful to swallow. 

For safety reasons, none of the scientists have tasted the transgenic lettuce to see if it retains flavour, so it still has to be approved for human consumption. It will be years before the product might be available for both astronauts and people on Earth suffering from osteoporosis.

Growing food in space is an important issue if humans are to travel to other worlds. Carrying enough supplies from Earth to last for years will take up a lot of space and weight.  And when it comes to space travel, any extra weight means extra cost.

Future astronauts will also have to be farmers. But if the vegetable patch also doubles as a medicine cabinet, all the better.

ABOUT THE AUTHOR

Bob McDonald is the host of CBC Radio's award-winning weekly science program, Quirks & Quarks. He is also a science commentator for CBC News Network and CBC-TV's The National. He has received 12 honorary degrees and is an Officer of the Order of Canada.

now