Planning to go to Mars? You might want to stock up on your berries.
If we want to send astronauts to Mars, keeping them healthy and fit is one of the greatest concerns. Mars only has around 40% of Earth's gravity, which means that in time, the astronauts' muscles will deteriorate without proper care. A recent NASA study of International Space Station (ISS) astronauts found that mission durations ranging from 4-6 months show a maximum loss of 30% in muscle performance and a maximum loss of 15% in muscle mass. However, Martian explorers wouldn't have access to the same training facilities as on the ISS, and we're also not really sure what the long-term consequences of Martian gravity will be on the human body.
"While there is a relatively good understanding of the effects of microgravity on human physiology based on five decades of experience, the physiological consequences of partial gravity remain far less well understood," researchers write in the new study.
Regardless of how bad muscular degradation will be, it's safe to say that there will be a lot of it to deal with.
"After just 3 weeks in space, the human soleus muscle shrinks by a third," says Dr. Marie Mortreux, lead author of the NASA-funded study at the laboratory of Dr. Seward Rutkove, Beth Israel Deaconess Medical Center, Harvard Medical School. "This is accompanied by a loss of slow-twitch muscle fibers, which are needed for endurance."
Researchers are looking for simple medical interventions that can help mitigate this damage, and among them, nutraceuticals stand out. 'Nutraceutical' is just a fancy word for functional food -- in other words, researchers are looking for dietary compounds that can help muscular and skeletal degradation. In particular, researchers focused on a natural phenol called resveratrol.
Resveratrol is commonly found in a variety of plants, from grapes and peanut plants to a myriad of shrub berries, including blueberries, raspberries, mulberries, cranberries, and bilberries. It can also be found in red wine. Resveratrol has been proven to be safe for human consumption and has been touted as a wonder supplement, although there is very little evidence that consuming resveratrol affects life expectancy or human health.
Resveratrol is widely investigated for its anti-inflammatory, anti-oxidative, and anti-diabetic effects, but the results have been insufficient so far. However, while the results are yet to be confirmed in humans, resveratrol has shown some promise -- and it has been proven to work in mice, which is why Mortreux and her team wanted to test it in a Mars-like environment
"Resveratrol has been shown to preserve bone and muscle mass in rats during complete unloading, analogous to microgravity during spaceflight. So, we hypothesized that a moderate daily dose would help mitigate muscle deconditioning in a Mars gravity analogue, too," says Mortreux.
To mimic the Martian environment, they used a setup in which rats were fitted with a full-body harness and suspended by a chain from their cage ceiling. They had 24 male rats exposed to normal loading (as on Earth), and another group at 40% Earth loading (as on Mars). All other things were kept equal.
For starters, they found that resveratrol supplements did not influence body weight and produce any detectable negative effects. Resveratrol was found to substantially preserve muscle mass and strength in the Mars rats group. It preserved front and rear paw grip almost entirely, although protection was not complete.
The results are intriguing, although there are a few significant limitations of this study. For starters, it involved a relatively small number of male rats -- we don't know if females would get the same benefits, or if a larger group would carry similar findings. Furthermore, this does not guarantee that the same will carry on for humans. The matter of dosage is also uncertain. Researchers drew inspiration from previous studies to administer a single daily dose, but other dosage combinations might be better suited and yield better results. The underlying mechanism of this protective process is also not fully understood and lastly, studies will also need to ensure that resveratrol doesn't interfere with other drugs routinely taken by astronauts.
This being said, however, resveratrol shows substantial promise and researchers call for additional research in this direction.
"Taken together, our results highlight the therapeutic potential of RSV as a nutraceutical countermeasure to prevent muscle deconditioning in an animal model of Martian gravity. Further investigations should optimize the dose of RSV for the preservation of muscle function and explore the mechanisms involved. In addition, it will be important to confirm the lack of any potentially harmful interactions of RSV with other drugs administered to astronauts during space missions," the study concludes.
Journal Reference: Marie Mortreux et al, A Moderate Daily Dose of Resveratrol Mitigates Muscle Deconditioning in a Martian Gravity Analog, Frontiers in Physiology (2019). DOI: 10.3389/fphys.2019.00899