What does boron do?
Boron is a nonmetallic element present in the diet and in the human body in trace amounts. Whether boron is an essential nutrient for humans remains in debate.
Boron appears to affect the metabolism of calcium, magnesium, copper, phosphorus, and vitamin D. Preliminary research suggests that boron might affect bone and joint health, but little specific information is known. The most promising research with boron has linked supplementation to reduced loss of calcium in urine. This effect might lead to a lower risk of osteoporosis, but decreased loss of calcium from boron supplementation occurs mostly when people are not getting enough magnesium in their diets.1
Where is boron found?
Raisins, prunes, and nuts are generally excellent sources of boron. Fruit (other than citrus), vegetables, and legumes also typically contain significant amounts. Actual amounts vary widely, depending upon boron levels in soil where the food is grown.
Who is likely to be deficient of boron?
As boron is not yet considered an essential nutrient for humans, it is not clear whether deficiencies occur. However, diets that are low in fruit, vegetables, legumes, and nuts provide less boron than diets that contain more of these foods.
How much boron is usually taken?
A leading boron expert has suggested 1 mg per day of boron is a reasonable amount to consume.2 People who eat adequate amounts of produce, nuts, and legumes are likely already eating two to six times this amount.3 Therefore, whether the average person would benefit by supplementing with this mineral remains unclear.
Are there any side effects or interactions with boron?
Accidental acute exposure to high levels of boron can cause nausea, vomiting, abdominal pain, rash, convulsions, and other symptoms.4 Although chronic exposures can cause related problems, the small (usually 1–3 mg per day) amounts found in supplements have not been linked with toxicity in most reports. Nonetheless, in one double-blind trial using 2.5 mg of boron per day for two months, hot flashes and night sweats worsened in 21 of 43 women, though the same symptoms improved in 10 others.5 Women whose have hot flashes or night sweats have been diagnosed as menopausal symptoms and who supplement with boron should consider discontinuing use of boron-containing supplements to see if the severity of their symptoms is reduced.
One study found that 3 mg per day resulted in increased estrogen and testosterone levels.6 Increased estrogen has also been reported in several women taking 2.5 mg per day.7 The increase in estrogen is of concern because it could theoretically increase the risk of several cancers. Although no increased risk of cancer has been reported in areas of the world where boron intake is high, some doctors recommend that supplemental boron intake be limited to a maximum of 1 mg per day.
The relationship between boron and other minerals is complex and remains poorly understood. Boron may conserve the body’s use of calcium, magnesium, and vitamin D. In one study, the ability of boron to reduce urinary loss of calcium disappeared when subjects were also given magnesium.8 Therefore, boron may provide no special benefit in maintaining bone mass in the presence of adequate amounts of dietary magnesium.
At the time of writing, there were no well-known drug interactions with boron.