Fermented foods might be beneficial for digestion but the human body is really, really good at eliminating metabolic toxins and there is zero evidence that there is any need to ever do anything to assist this process or that you even can...although, in one way or another, this has been a recurring quackery theme over time...bloodletting, purgatives, enemas and colonics...
Randomly clicking around on Google News.
This article on metabolism boosting foods has the following crazy statement,
"Taking a swig of sauerkraut juice. This helps keep my gut healthy, which ensures that I'm eliminating everything by body needs to get rid of. When your digestive system slows down and gets stagnant, you start to recirculate toxins and, for women, estrogens, which can contribute to weight gain. I've also always found that when I'm regular, I'm more likely to make healthy food choices."
Is there any reason anyone would think this is something that happens?
By that logic, it seems teen girls would be trying to stay constipated in hopes the extra estrogen would boost their breast size.