Boron is a trace mineral that occurs naturally in fruits, vegetables, and nuts. Humans do not need it to survive, but people take supplemental forms to help maintain bone density, keep joints comfortable, and support the way the body handles sex hormones such as testosterone and estrogen.
Many older adults use it to aid joint health and mobility. Men sometimes take it to keep testosterone levels in a healthy range. A few people also use it for focus and brain function, though the science there is less solid.
You can take boron as a capsule or tablet, preferably with a meal for better absorption. Common daily doses run from 3 to 10 mg, and starting low is wise.
Too much boron becomes toxic and can trigger nausea, vomiting, and diarrhea. The mineral may interfere with some medicines, including hormone therapies. Anyone with kidney trouble should skip supplementation unless a doctor advises otherwise.