Recommended dosage of boron?

For boron supplementation, Kyle Gillett recommends taking three to six milligrams once to twice a day. This dosage is suggested because it's unlikely to have a negative effect and can help regulate SHBG (Sex Hormone Binding Globulin), even if its effects are mostly acute. Andrew Huberman also discusses taking boron in smaller doses of two to four milligrams per day as part of his personal regimen 1.