Making it to the top of Mount Everest is no small feat—thousands of experienced climbers have tried and failed. And unfortunately, hundreds have lost their lives on the white whale of the climbing world. Just this Saturday, 34-year-old Maria Strydom of Australia died after developing high-altitude pulmonary edema—an extreme form of altitude sickness—which caused fluid to build up in her brain.

Maria, an outspoken vegan and a finance lecturer at Monash Business School in Melbourne, was no amateur climber. Along with her husband, she was on a quest to climb the world’s seven most challenging summits to prove that “vegans can do anything.”

But in a sad twist, her vegan diet may have contributed to her death on the mountain.

“Altitude sickness can affect anyone,” says Niket Sonpal, M.D., assistant clinical professor at Touro College of Medicine in New York. “It’s an equal opportunity offender. But oxygen-carrying capacity is something that vegans can be affected by.”

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Vegan diets are commonly lacking in vitamin B12, says Sonpal. This is the nutrient that allows red blood cells to carry oxygen to vital organs like our hearts and brains.

So although Maria was an experienced climber with a seasoned team, if she was deficient in B12, it’s possible that her diet could have played some role in her death, causing a lack of oxygen to the brain.

What does this mean for you? “If you are planning to adopt a vegan diet, the fact of the matter remains that you should be much more in touch with physicians,” says Sonpal. And that’s especially true if you’re placing your body in taxing, high-performance situations.

Macaela Mackenzie Macaela Mackenzie is a freelance journalist specializing in health, culture, and tech, and she regularly contributes to outlets like Prevention, Women’s Health, Shape, Allure, Men’s Health, the John Hopkins Health Review, and more.

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