Boron

What does it do? Boron is a non-metallic 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 very little is known regarding specifics. 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 it 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.

Boron has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
1Star Osteoarthritis
Osteoporosis
Rheumatoid arthritis
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? 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 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? 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.

References:

1. Nielsen FH. Boron—an overlooked element of potential nutritional importance. Nutr Today 1988(Jan/Feb);23:4–7.

2. Nielsen FH. Facts and fallacies about boron. Nutr Today 1992(May/Jun):6–12.

3. Kelly GS. Boron: a review of its nutritional interactions and therapeutic uses. Altern Med Rev 1997;2:48–56 [review].

4. Nielsen FH. Ultratrace minerals: Boron. In: Shils ME, Young VR (eds). Modern Nutrition in Health and Disease. Philadelphia: Lea & Febiger 1988, 281–3 [review].

5. Nielsen FH, Penland JG. Boron supplementation of peri-menopausal women affects boron metabolism and indices associated with macromineral metabolism, hormonal status and immune function. J Trace Elem Exp Med 1999;12:251–61.

6. Nielsen FH, Hunt CD, Mullen LM, Hunt JR. Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women. FASEB J 1987;1:394–7.

7. Nielsen FH, Penland JG. Boron supplementation of per-menopausal women affects boron metabolism and indices associated with macromineral metabolism, hormonal status and immune function. J Trace Elem Exp Med 1999;12:251–61.

8. Hunt CD, Herbel JL, Nielsen FH. Metabolic responses of postmenopausal women to supplemental dietary boron and aluminum during usual and low magnesium intake: boron, calcium, and magnesium absorption and retention and blood mineral concentrations. Am J Clin Nutr 1997;65:803–13.