Borax is sold as a laundry product. It's not soap. It is literally scraped off the ground from dried lake beds in California and Turkey among other places. It is a naturally occurring mineral, boron, that is essential to our health. Any food grown with fertilizer...fertilizer inhibits the natural uptake of boron from the soil to the plant, and as a result, there is quite a bit of boron deficiency in our diets. What a stupid cheap and simple way to put essential boron back into our diets. I can't even taste it when I add it to water. It also takes fluoride (along with heavy metals) out of your body, and despite what your government tells you, fluoride taken internally is not good for your health at all, and the worst way to get it to your teeth. Fluoride is good for teeth applied right on the tooth, but taken internally is detrimental to your system. The more fluoride you have in your body, the more it leaches mercury from dental work into your system. But that's not the only downside to fluoride taken internally.
For more about fluoride, watch this great documentary, over an hour long, about the dangers of fluoride called Flouridegate: