So regular cells need oxygen, but cancerous ones don’t? Aren’t cancer cells just regular cells sped up? They divide way faster than normal, which is why some chemotherapies work—they poison the dividing process (called mitosis). But how can growing cells not need oxygen? Doesn’t every cell need oxygen? The answer is a resounding no. In fact, there’s very little oxygen in the gut. The intestinal microbiome has adapted to it; 99 percent of the bacteria in our intestine, called obligate anaerobes, don’t need oxygen. In fact, many bacteria grow just fine without it and don’t have mitochondria.
