Space lettuce could reduce bone loss in astronauts

(ORDO NEWS) — The first people to go to Mars will face a variety of problems. One of them, which is much discussed and does not yet have a potential solution, is the possibility of a significant loss of bone density during a three-year mission.

In microgravity conditions on the ISS, astronauts lose about 1% of bone density per month. It’s not too much of an issue if they’ve only been on the station for six months, but two 10-month space trips on a mission to the red planet could be a concern. Now a team of researchers think they have a solution – have the astronauts eat more lettuce.

Lettuce, which is commonly used as a base for salads, is not particularly good for bone density in its normal form. However, a fragment of a peptide called human parathyroid hormone (PTH) is useful. It can stimulate bone growth, which can help combat osteopenia, the loss of bone density associated with low gravity.

Usually PTH is taken by injection, but for spaceflight this is most likely not suitable – the serum and syringes needed to administer the required amount of the drug would be prohibitively expensive to launch.

Fortunately, injections are not the only way to get drugs. In some cases, they can simply be eaten. So far no one has bothered to do this for PTH, but now Kevin Yates, a UC Davis graduate student, and colleagues have developed a transgenic form of lettuce that can express PTH. They presented their research at the annual meeting of the American Chemical Society in March.

To create a transgenic lettuce, the team turned to a standard technique for endowing a plant with a specific gene – they infected it with a bacterium known as Agrobacterium tumefaciens.

In preliminary studies, the bacteria seemed to be doing their job well, causing lettuce to produce 10 to 12 milligrams of PTH per kilogram. At current levels, each astronaut needs to eat about 8 cups of lettuce a day to get enough PTH to prevent bone loss, which Yates admits is “a pretty big salad.”

But there is room for improvement. It is assumed that only 10% of the PTH produced by the plant enters the human body, but this has not yet been proven.

So far, the researchers have not infected the modified culture themselves, as they are waiting for the results of animal studies to prove its safety. If other genetically modified crops are any indication, lettuce should be safe to eat and taste like a traditional variety.

The benefit of genetically modified crops is that scientists can select the strains with the most traits they are looking for and keep trying to improve on that best strain. Yates and his colleagues hope to do this with the lettuce they created, potentially boosting yields significantly.

Once they find a variety that suits them, they’ll want to test it on the space station. This won’t be the first time astronauts have grown lettuce on the ISS, but it’s worth checking to see if this modified variety suffers from any debilitating side effects in microgravity.

Assuming not, it’s relatively easy and inexpensive to start tiny seeds that can eventually grow into a full-fledged lettuce for PTH production.

But space isn’t the only place this form of lettuce could prove useful: there are areas on Earth that suffer from a lack of traditional medicine, and a lack of PTH could lead to degenerative bone disease in these people.

Instead of a massive and sustained treatment effort in these parts of the world, a new lettuce variety could reduce the loss of bone density in their populations.

Whether all this will come true is still unknown. NASA is planning the first mission to Mars only in the 2030s, so we still have a lot of time to work on perfecting the crop. And perhaps astronauts on this mission will be able to enjoy once a day delicious, unfrozen dried leafy food. If it helps them avoid debilitating bone disease, so much the better.


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