The average reported boron intake in the American diet is 1.17 milligrams per day for men, 0.96 milligrams per day for women and 1.29 to 1.47 milligrams per day for vegetarians. High boron content foods include peanut butter, wine, grapes, beans, and peaches. 2.5 to 6 milligrams have been taken by mouth in studies.
For psoriasis, 1.5% boric acid with 3% zinc oxide ointment applied to the skin as needed has been studied. Boric acid powder capsules administered vaginally daily have also been studied. Safety and effectiveness have not been well established.
There is not enough scientific data to recommend the safe use of boron in children. Case reports exist of death in infants following the use of boron (taken by mouth or placed on the skin).
Boron should be avoided in patients who have a history of reactions to boron, boric acid, borax, citrate, aspartate, or glycinate.
Boron is potentially toxic, although humans tend to rapidly excrete it and therefore boron does not usually accumulate in high levels. In adults, it is believed that adverse reactions associated with low doses of boron per day are less likely to occur, and there are few reports of toxicity. Large doses may result in acute poisoning. There are fatal case reports of infants who have been exposed to boron by mouth or on the skin. Historically, a honey and borax solution was used to clean infant pacifiers, and topical boric acid powder was used to prevent diaper rash. However, these practices were associated with several infant deaths.
Boron toxicity may cause skin rash, nausea, vomiting (may be blue-green color), diarrhea (may be blue-green color), abdominal pain, and headache. Low blood pressure and metabolic changes in the blood (acidosis) have been reported. Agitation and irritability, or the opposite reaction (weakness, lethargy, depression), may occur. Fever, hyperthermia, tremors, and seizure have been reported. Based on animal study, excess amounts of boron ingestion have been shown to cause testicular toxicity, decreased sperm motility, and reduced fertility. Hair loss has been reported with boron poisoning. Chronic boron exposure may cause dehydration, seizures, low red blood cell count, as well as kidney or liver damage.
Boron is proposed to increase blood levels of estrogen and testosterone, with mixed results of research. Boron may be associated with reduced blood levels of calcitonin, insulin, or phosphorus and with increased levels of vitamin D2, calcium, copper, magnesium, or thyroxine. Exposure to boric acid or boron oxide dust can cause eye irritation, dryness of the mouth or nose, sore throat, and productive cough.
There is not enough scientific evidence to recommend the safe use of boron during pregnancy or breastfeeding. There is a trace amount of boron distributed to human milk. Excessive amounts of boron taken by mouth may cause toxicity in male fertility.