It is a trace mineral. Studies show that Boron helps the body retain minerals, such as Calcium and Magnesium. Large amounts of Boron, over 10 milligrams a day, can be toxic, particularly to the organs that manufacture testosterone. You can find traces of Boron in all the food groups, even in wine, with the greatest concentration in prunes, raisins, parsley flakes, and almonds. A 1987 study showed that Boron could dramatically increase testosterone levels, however, the study was for postmenopausal women who had testosterone deficiencies. Once their boron-rich diets brought their testosterone levels back up to normal, those levels stabilized, and they didn't get any higher no matter how many more prunes or parsley flakes that they ate. Thus, it is somewhat unproven that boron can help build muscle mass by increasing your testosterone levels. However, a lack of boron in your diet may have a 'negative' impact on energy utilization.