Boron (B)

B – Boron is found in igneous rocks shale 100 ppm; sandstones at 35 PPM; limestone at 20 ppm; fresh water at 0.0 13 ppm; sea water at 4.0 to 6.0 ppm; soil 2.0 to 100 ppm (highest in saline and alkaline soils); in California certain deserts have toxic levels; marine plants 120 ppm (highest in brown algae); land plants a at 5 0 ppm; Chenopodiaceae and Plumboginaceae are indicator plant families; marine animals at 20 to 50 ppm; land animals 0.5 ppm; boron is essential for bone metabolism including efficient use of calcium and magnesium and proper function of endocrine glands (i.e. ovaries, testes and adrenals).

Pure boron is hard and gray and melts at over 4,000 degrees F. Boron, a non-metallic mineral, occurs as a combination in nature, i.e. borax, boric acid (sassolite), ulexite, colemanite, boracite and tourmaline.

Large deposits of borax or “diamond boron” were discovered in Death Valley in 1881. The Death Valley deposits were made famous by the 20-mule team wagons that hauled out the mined borax. The rear wheels were 7 foot high, each wagon bed was 16 foot long and could carry 24,000 pounds (12 tons) of borax. Each 20 mule team pulled two wagons plus a 1,200 gallon water wagon (36.5 tons in each load! 1), the total length of the team and equipment was 120 foot long. The railhead in Mojave was 165 miles from the Death Valley mine site.

Prior to 1981, boron was not considered an essential nutrient; boron was first shown to be an essential mineral for growing chicks. It was not until 1990 that boron was accepted as an essential nutrient for humans.

Boron is required for the maintenance of bone and normal blood levels of estrogen and testosterone; within eight days of supplementing boron women lost 40 percent less calcium, 33 percent less magnesium and less phosphorus through their urine.

Women getting boron supplementation had blood levels of estradiol 17B doubled to 1evels found in women on estrogen replacement therapy,” the at 10 ppm; levels of testosterone almost doubles.

More is becoming known of the biochemical function of boron in human and animal tissues. Because boron affects steroid hormone metabolism in humans and animals, and because the response of experimental animals to boron deficiency seems to be enhanced by nutritional stressors that induce secondary hyperparathyroidism (i.e. magnesium deficiency and aluminum toxicity, it would not be surprising to find that boron affects major mineral metabolism via a regulatory role involving a hormone.

Boron deficiency

The signs of boron deficiency in animals vary in nature and severity as the dietary content of aluminum, calcium, cholecalciferol, magnesium, methionine and potassium is varied. Variables affected by dietary boron include plasma and organ calcium and magnesium concentrations, plasma alkaline phosphatase, and bone calcification. Two studies showing a response to boron deprivation in humans have been reported. The first, on postmenopausal women housed in a metabolic unit, indicated that a low boron diet (0.25 mg/2000 kcal) elevated urinary excretion of calcium and magnesium, and depressed serum concentrations of 17fl-estradiol and ionized calcium. The second, in which five men, nine postmenopausal women (five on estrogen therapy) and one premenopausal woman were fed a low-magnesium, marginal copper diet, showed that plasma ionized calcium and serum 25-hydroxycholecalciferol were lower and serum calcitonin and osteocalcin were higher during boron depletion (0.23 mg/2000 kcal) than during boron repletion. Brain function was affected in these 15 adults; electroencephalograms indicated that they were less mentally alert during boron depletion than during boron repletion. In these experiments the first 21 days of depletion were not included in the statistical analyses because there were no apparent changes in variables of interest. Peace et al. also failed to find any significant effects in postmenopausal women fed a low-boron diet (0.33 mg/day) for 21 days.

Boron’s essentiality

Boron is an essential mineral nutrient found in trace amounts in most tissues. Although its precise role is unclear, boron may function in bone formation in both women and men and may also help prevent CALCIUM and MAGNESIUM losses in postmenopausal women. Boron seems to aid in the formation of steroid hormones (estrogen) and vitamin D and estrogen, and it improves COPPER metabolism. A magnesium deficiency accentuates the effects of boron. As yet there is no Recommended Dietary Allowance (RDA) for boron because a requirement has not yet been quantified. An estimated safe and adequate daily intake is I to 3 mg for adults. Sources of boron include legumes, leafy vegetables and fruit; APPLES, GRAPES and PEARS are good sources. A varied diet would be expected to supply adequate amounts of this mineral. Excessive use of boron supplements can cause a dangerous overdose of boron.

Newnham, R.E., “‘Essentiality of Boron for Healthy Bones and joints,”‘ Environmental Health Perspectives, 102:supplement (November 1994), pp. 83-85.

The Clinical Effects of Boron (B)
by E. Blaurock-Busch, PhD


Boric acid was mentioned by the famous Arab researcher Geber who died in 776 AD. Latin scriptures and translations dating from the early Middle Ages referred to it as “Borach,” “Baurauch,” or “Bauracon,” a precious commodity that was imported from Tibet under the name of Tinkal or Tinkar. Elemental boron wasn’t discovered until 1810 by Davy, and was finally produced in pure form by Moissan at the end of the 19th century.

Physiological Aspects

Boron is considered a catalytic trace element in humans and animals. The works of Albrecht and others have shown that boron has considerable involvement in glycogen synthesis in the liver. Bersin demonstrated that boron deficiency in humans with a tendency to skin allergies can trigger eczema, acne, and enteritis. Russian researchers emphasized the relationship of boron to adrenaline, carbohydrate and lipid metabolism. More recently, it has been recognized that this trace element plays a role in the prevention and treatment of osteoporosis and it has been suggested that it be involved in the formation of specific steroid hormones. There is some evidence that osteoporotic women who take boron supplements increase their serum hormone levels.


Plenty of data supports the hypothesis that boron is an essential element and that it is involved in regulating parathormone action. Therefore, it is likely that boron influences the metabolism of calcium, phosphorus, magnesium and cholecalciferol. Animal studies have indicated that cholecalciferol deficiency enhances the need for boron, and that boron might interact in some manner other than through an effect on cholecalciferol metabolism. The relationship seemed strongest between boron and magnesium, because boron supplementation alleviated magnesium deficiency signs in chicks. Boron does not seem to consistently alleviate signs of calcium and phosphorus deficiency. Elsair and co-workers found that a high dietary boron intake partially alleviated fluoride induced secondary hyperparathyroidism signs of hypercalcemia, hypophosphatemia, and depressed renal absorption of phosphorus in rabbits.

Boron and boron compounds can influence calcium metabolism, and tissue boron level changes in animals with abnormal calcium metabolism. In humans, a low caries incidence has been associated with adequate boron levels; however other studies indicated that high levels of orally administered boron increased dental caries. Boron has been shown to affect the activity of numerous enzymes in both plants and animals. Lewin and Chen stated that boron might have a role as a cofactor for some enzymatic reactions and also inhibits some enzymes, namely the pyridine or flavin I nucleotide-requiring oxidoreductases, cytochrome b5 reductase, and chymotrypsin.


Boron is rapidly absorbed, and excreted mainly in urine. Urinary recoveries depend on the dietary intake and may range from 30-90%. Kidney problems reduce excretion, causing potential boron accumulation in the heart, lungs, kidneys, brain, reproductive glands and adipose tissues. Years ago, boric acid was administered at 0.5 g/day to achieve weight loss. This dosage caused boric acid diarrhea, in addition to considerable deterioration of nutrient absorption.

Selected reported deficiency signs of Boron

Decreased calcium content and force required to break vertebrae of calcium-deficient rats; more severe signs of rickets in cholecalciferol (Vit. D)-deficient chicks; decreased apparent absorption and balance of calcium, magnesium and phosphorus; increased calcium concentration in brain cortex and increased phosphorus concentration in cerebellum of Vitamin D – deprived rats; decreased Red Blood Cell superoxide dismutase levels; increased plasma calcium, serum creatinine, and blood urea nitrogen (BUN); impaired performance in computer tasks and electroencephalograms indicating depressed mental alertness in postmenopausal women and men over the age of 45.

Possible functions of Boron

Through reactions with certain biosubstances to maintain proper cell membrane function or stability and influences hormone reception and transmembrane signaling.

Dietary need and sources

Human requirement of Boron most likely between 0.5 and 1.0 mg/day; rich food sources include noncitrus fruits, leafy vegetables, nuts, pulses and legumes.

Boron toxicology

Toxic effects appear at intakes of about 100 mg. The World Health Organization has banned boron (in the form of boric acid) as a food additive and preservative. Toxic effects include a red rash with weeping skin, vomiting, diarrhea characterized by a blue green color, depressed blood circulation, coma and convulsions. A fatal dose in adults is 15 to 20 g and in children 3 to 6 g. Repeated intakes of small amounts can cause accumulative toxicity. Signs of toxicity include nausea, vomiting, diarrhea, dermatitis, and lethargy. In addition, excess boron intake induces riboflavinuria. Landauer found that boron-induced teratogenic problems include skeletal abnormalities and were reduced with riboflavin therapy.

Oral administration of boron has low toxicity. A maximum tolerable level of 150 ug boron (as borax) per gram of dry diet has been suggested for cattle. Continuous feeding tests with rats have shown that boron levels in food of 73 ppm cause growth problems. When food contained 385 ppm boron, which corresponds to an uptake of 60.7 mg/kg, histological organ changes were observed, especially testicular atrophy. Cows consuming 150-300 mg/L of boron exhibited inflammation and edema in the legs and around the dewclaws. Furthermore, reduced feed intake, growth, hematocrit, hemoglobin, and plasma phosphorus was observed. Green et al. found that when boron levels of drinking water exceed 150 mg/L, rats exhibit depressed growth, continued prepubescent fur, aspermia, and impaired ovarian development. When drinking’ water levels exceeded 300 mg/L, rats exhibit depressed plasma triglycerides, protein and alkaline phosphates, and depressed bone calcium.

Therapeutic considerations: check calcium, magnesium, phosphorus and riboflavin levels. Vitamin B6 reduces or abolishes the teratogenic effects of boric acid.

Distribution and Laboratory Analysis

Although boron is distributed throughout the tissues and organs of animals and humans, boron is mainly stored in bones. The ashes of human bones yield between 16 and 138 ppm of boron. Dental enamel varies widely in boron content and the concentration found in hair is similar to that of soft tissue. Plasma boron levels are apparently relatively high at birth, and decrease by about 50% within five days. Human milk contains boron at about one tenth the levels found in blood. Water containing 150-300 mg/L seems to cause inflammation and edema in the legs and other health problems.


A study was conducted to examine the effects of aluminum, magnesium, and boron on major mineral metabolism in postmenopausal women. This communication describes some of the effects of dietary boron on 12 women between the ages of 48 and 82. A boron supplement of three mg/day markedly affected several indices of mineral metabolism in seven women consuming a low-magnesium diet and five women consuming a diet adequate in magnesium. An adequate-magnesium diet was considered to be about 0.25 mg boron/day for 119 days. Boron supplementation markedly reduced the urinary excretion of calcium and magnesium. The reduction in calcium and magnesium excretion was greater when dietary magnesium was low. Boron supplementation depressed the urinary excretion of phosphorus only in women with low-magnesium diets. Boron supplementation markedly elevated the serum concentrations of 170-estradiol and testosterone. The elevation was more dramatic when dietary magnesium was low. Neither high dietary aluminum (1,000 mg/day) nor an interaction between boron and aluminum affected the variables presented. The findings suggest that supplementation of low-boron diets with a typical amount of boron induces changes in postmenopausal women, consistent with the prevention of calcium loss and bone demineralization. Prog Food Nutr Sci 1993 Oct;17(4):331-349

The role of boron in nutrition and metabolism.
Naghii MR, Samman S

Department of Biochemistry, University of Sydney, NSW, Australia.

A large number of responses to dietary boron occur when the boron content of the diet is manipulated. Numerous studies suggest that boron interacts with other nutrients and plays a regulatory role in the metabolism of minerals, such as calcium, and subsequently bone metabolism. Although the mechanism of action has not been defined, it may be mediated by increasing the concentration of steroid hormones such as testosterone and beta-estradiol. Boron is obtained from a diet rich in fruits, vegetables, nuts and legumes. The daily intake has been estimated to range from 0.3-41 mg per day. The wide range is due to the variation of the analytical methods used and differences in the soil content of boron. Based on a limited number of studies, increasing dietary boron results in increases in the boron concentration of all tissues. Large amounts of boron are well tolerated while consistent signs of deficiency include depressed growth and a reduction in some blood indices, particularly steroid hormone concentrations. Via its effect on steroid hormones and interaction with mineral metabolism, boron may be involved in a number of clinical conditions such as arthritis.

Environ Health Perspect 1994 Nov;102 Suppl 7:59-63

Biochemical and physiologic consequences of boron deprivation in humans.
Nielsen FH

United States Department of Agriculture, Agricultural Research Service, Grand Forks, North Dakota 58202-9034.

Boron deprivation experiments with humans have yielded some persuasive findings for the hypothesis that boron is an essential nutrient. In the first nutritional study with humans involving boron, 12 postmenopausal women first were fed a diet that provided 0.25 mg boron/2000 kcal for 119 days, and then were fed the same diet with a boron supplement of 3 mg boron/day for 48 days. The boron supplementation reduced the total plasma concentration of calcium and the urinary excretions of calcium and magnesium, and elevated the serum concentrations of 17 beta-estradiol and testosterone. This study was followed by one in which five men over the age of 45, four postmenopausal women, and five postmenopausal women on estrogen therapy were fed a boron-low diet (0.23 mg/2000 kcal) for 63 days, then fed the same diet supplemented with 3 mg boron/day for 49 days. The diet was low in magnesium (115 mg/2000 kcal) and marginally adequate in copper (1.6 mg/2000 kcal) throughout the study. This experiment found higher erythrocyte superoxide dismutase, serum enzymatic ceruloplasmin, and plasma copper during boron repletion than boron depletion. The design of the most recent experiment was the same as the second study, except this time the diet was adequate in magnesium and copper. Estrogen therapy increased plasma copper and serum 17 beta-estradiol concentrations; the increases were depressed by boron deprivation. Estrogen ingestion also increased serum immunoreactive ceruloplasmin and erythrocyte superoxide dismutase; these variables also were higher during boron repletion than depletion for all subjects, not just those ingesting estrogen.

Magnes Trace Elem 1990;9(2):61-69

Studies on the relationship between boron and magnesium which possibly affects the formation and maintenance of bones.
Nielsen FH

United States Department of Agriculture, Grand Forks Human Nutrition Research Center, N. Dak.

Recent findings are reviewed indicating that changes in dietary boron and magnesium affect calcium, and thus bone, metabolism in animals and humans. In animals, the need for boron was found to be enhanced when they needed to respond to a nutritional stress which adversely affected calcium metabolism, including magnesium deficiency. A combined deficiency of boron and magnesium caused detrimental changes in the bones of animals. However, boron deprivation did not seem to enhance the requirement for magnesium. In two human studies, boron deprivation caused changes in variables associated with calcium metabolism in a manner that could be construed as being detrimental to bone formation and maintenance; these changes apparently were enhanced by low dietary magnesium. Changes caused by boron deprivation included depressed plasma ionized calcium and calcitonin as well as elevated plasma total calcium and urinary excretion of calcium. In one human study, magnesium deprivation depressed plasma ionized calcium and cholesterol. Because boron and/or magnesium deprivation causes changes similar to those seen in women with postmenopausal osteoporosis, these elements are apparently needed for optimal calcium metabolism and are thus needed to prevent the excessive bone loss which often occurs in postmenopausal women and older men.


Environ Health Perspect 1994 Nov;102 Suppl 7:49-53

Relation of boron to the composition and mechanical properties of bone.
McCoy H, Kenney MA, Montgomery C, Irwin A, Williams L, Orrell R

Agricultural Experiment Station, University of Arkansas, Fayetteville 72701.

A review of the experimental studies relating boron to biological effects on appendicular and axial bones in animal models suggests that numerous influences, known and unknown, affect the responsiveness of bone to dietary boron. Degrees of skeletal response to boron are modified by other nutritional variables that include calcium, magnesium, vitamin D, and fluoride. Evidence suggests that appendicular and axial bones may differ in their responses. Tests of the mechanical properties of bones may provide useful criteria for assessing the impacts of boron status on bone. These tests might resolve questions about optimal intakes of boron because mechanical properties sometimes respond to boron when composition of bones does not. Difficulty in interpreting some of the existing research arises because of the incipient state of knowledge regarding boron nutrition, to analytical problems associated with determining accurately the small quantities of boron in feed and tissues, and to technological difficulties in controlling extraneous exposure of experimental animals to boron. Yet there is considerable evidence that both compositional and functional properties of bone are affected by boron status.

Biol Trace Elem Res 1997 Mar;56(3):287-294

Effects of boron on growing pullets.
Wilson JH, Ruszler PL

Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg 24061-0303, USA.

The effect of dietary boron on bone ash content and on the ultimate shear force, stress, and fracture energy of the tibia, femur, humerus, and radius from white Leghorn pullets were investigated. There was a significant increase in the shear force of the tibia and femur for pullets supplemented with 50 and 100 mg/kg of dietary boron. There was a significant increase in the shear stress of the tibia at 50 and 100 mg/kg of boron, and also an increase in shear fracture energy at 50 and 100 mg/kg boron for the femur. Tibia bone ash content increased significantly at 50, 100, and 200 mg/kg boron with the highest value at 50 mg/kg. Even though there was not a significant increase in body wt at 50 and 100 mg/kg boron, the pullets fed these supplements were consistently heavier than the control group.

Environ Health Perspect 1994 Nov;102 Suppl 7:79-82

Effects of boron supplementation on bone mineral density and dietary, blood, and urinary calcium, phosphorus, magnesium, and boron in female athletes.
Meacham SL, Taper LJ, Volpe SL

Department of Human Nutrition, Winthrop University, Rock Hill, South Carolina 29733.

The effects of boron supplementation on blood and urinary minerals were studied in female college students–17 athletes and 11 sedentary controls–over a one-year period. The athletes had lower percent body fat and higher aerobic capacities than sedentary controls. Athletic subjects consumed more boron in their normal diets than sedentary subjects; all other dietary measures were similar between the two groups. The athletes showed a slight increase in bone mineral density, whereas the sedentary group showed a slight decrease. Serum phosphorus concentrations were lower in boron-supplemented subjects than in subjects receiving placebos, and were lower at the end of the study period than during baseline analysis. Activity depressed changes in serum phosphorus in boron-supplemented subjects. Serum magnesium concentrations were greatest in the sedentary controls whose diets were supplemented with boron, and increased with time in all subjects. A group x supplement interaction was observed with serum magnesium; exercise in boron-supplemented subjects lowered serum magnesium. In all subjects, calcium excretion increased over time; in boron-supplemented subjects, boron excretion increased over time. In all subjects, boron supplementation affected serum phosphorus and magnesium, and the excretion of urinary boron.

Nutr Health 1999;13(1):31-7

The significance of dietary boron, with particular reference to athletes.
Naghii MR

University of Medical Sciences, Faculty of Health, Food Sciences & Nutrition group, Tehran, IR of Iran.

Ergogenic substances and synthetic steroids have a wide spread use, particularly among non-professional athletes. To avoid the side-effect of drug abuse, it is suggested that the key to success is a proper athletic nutrition. It is a balanced intake of nutritional wholesome foods that contain a proper blend of essential nutrients. Knowledge of human physiology and nutrition has increased greatly, and so has application of dietary alterations and supplementation with specific nutrients. Modulation of dietary composition and/or supplementation with specific nutrients with the intent of improving human physical performance is a working definition of nutritional ergogenic aids. Boron is a trace element nutrient, and recently its supplements have been shown to increase the concentration of plasma steroid hormones. In a single blind cross-over trial, it resulted in a significant increase in plasma 17-B estradiol (E2) concentration (P < 0.004) and there was a trend for plasma testosterone (T) levels to be increased. The ratio of E2/T increased significantly. However, there was no perturbation in plasma lipids. Furthermore, the effect of boron on steroidogenesis and its mechanism was also investigated in two more studies conducted on adult male rats. The elevation of endogenous steroid hormones as a result of boron supplementation suggest that boron may be used as an ergogenic safe substance for athletes which should be further investigated.

J Am Coll Nutr 1996 Dec;15(6):614-619

The boron content of selected foods and the estimation of its daily intake among free-living subjects.
Naghii MR, Wall PM, Samman S

Department of Biochemistry, University of Sydney, Australia.

BACKGROUND: Boron is an essential micronutrient for higher plants. The results of studies in animals and humans have suggested a potential role for boron as a modulator of the steroid hormone pathway. METHODS: As part of a study to obtain baseline information on boron in humans, the boron content of selected foods (66 items) consumed in Australia was determined. Mean values are presented for the element per 100 g or 100 ml of food and per serving.

RESULTS: Major sources of the element were nuts, dried fruits, legumes, fresh vegetables and fruits. The boron content of these foods correlated positively and strongly with values provided by the comprehensive Finnish Tables of mineral composition of foods and with the US Food and Drug Administration Total Diet Study.