The wide range of responses to boron are likely as a result of its involvement in cell signalling systems and/or the formation and/or activity involved in many biochemical processes. A plausible mechanism of action may be indicated by the biochemistry of boron. Boric acid forms ester complexes with hydroxyl groups of organic compounds, which results in the formation of complexes with several biologically important sugars. These sugars include ribose, which is a component of adenosine. Recent findings suggest that the diverse beneficial effects of boron occur through affecting the presence or action of biomolecules containing adenosine or formed from adenosine precursors. These biomolecules include S-adenosylmethionine and diadenosine phosphates (1). Diadenosine phosphates are present in all cells and functions as signal nucleotides involved with neuronal response. S-adenosylmethionine is one of the most frequently used enzyme substrates in the body which influences the activity of DNA, RNA, proteins, phospholipids, hormones, and transmitters and also S-adenosylhomocysteine, which can be hydrolysed into homocysteine (2) . High circulating homocysteine and depleted S-adenosylmethionine have been implicated in many of the disorders that can be affected by nutritional intakes of boron, including arthritis, osteoporosis, cancer, diabetes, and impaired brain function.
Both animals and humans deprived of boron exhibit positive health benefits when provided with intakes of boron that may be achieved through consuming foods of plant origin. Inhuman depletion–repletion experiments, participants responded to a 3 mg/d boron supplement after consuming a diet supplying only 0.2–0.4 mg boron/d for 63 days (3-5). Extrapolations from animal experiments indicate that to achieve optimal benefits of boron, intakes >0.5 mg/d are needed and that boron supplementation is unlikely to elicit a response in individuals consuming at least 1 mg boron/d (6). Thus, if an adequate intake level is ever established for the health benefits of boron, it is likely to be between 0.5 and 1.0 mg/d . In the United States, a survey conducted between 1994 and 1996 indicated boron intakes ranged from a low of 0.35 to a high of 3.25 mg/d for adults. The median intakes for various age groups of adults ranged from 0.87 to 1.13 mg/d (7). Findings from a study involving postmenopausal women found that average urinary excretion of boron, which is a good indicator of dietary intake, was less than 0.5 mg/d for two women and between 0.5 and 1.0 mg/d for 14 women (8). These findings suggest that a significant number of people could benefit through an increased intake of boron.
Sources of Boron
Data on dietary boron intake by human beings are fairly sparse. Boron is not included in the United States, and no comprehensive analytical database exists on the content of specific foods. The top two contributors, coffee and milk, are low in boron, yet they may make up 12% of the total intake by virtue of the volume consumed. Peanut butter, wine, raisins, apples, pears, grapes, avocados, legumes, peanuts and other nuts are good sources of boron. Diets low in fruits, vegetables, legumes and nuts may not provide an adequate amount of boron.
Boron in Health and Disease
Since 1981, occasional reports have appeared suggesting that boron can ameliorate or prevent arthritis. Animal studies have shown that boron can inhibit inflammatory responses to material injected to induce arthritic conditions (9,10). In 1990, it was reported that 15 individuals with confirmed osteoarthritis completed a double-blind study in which they were given either a supplement of 6 mg boron or placebo daily for eight weeks (11). Five of the seven subjects consuming the boron supplement reported improved subjective measures such as less pain on movement for their arthritic condition. Only one of eight subjects consuming the placebo reported improved subjective measures. More recent studies suggesting that boron may ameliorate arthritic conditions includes a report (12) that a 6 mg/d boron supplement in the form of calcium fructoborate, a naturally occurring boron complex found in fruits and vegetables, alleviated subjective measures of mild, moderate, or severe osteoarthritis in 20 subjects. After eight weeks of supplementation, 80% of patients with mild or moderate osteoarthritis reported reduced or eliminated use of painkillers. In addition, joint rigidity essentially disappeared, and mobility was markedly increased. Patients with severe arthritis, who were supplemented daily with 12 mg boron as calcium fructoborate, had a more subdued improvement in mobility and rigidity, but did report a significant reduction in painkillers. Subsequently, a double-blind, placebo-controlled pilot study was done to evaluate the effect of calcium fructoborate on systemic inflammation in middle-aged subjects with primary knee osteoarthritis (13). The study was completed by 60 subjects in which groups of 15 were supplemented with a placebo or boron at 3, 6, or 12 mg/d as calcium fructoborate for 15 days. When all boron-supplemented subjects were grouped together, inflammatory stress biomarkers serum C-reactive protein, plasma fibrinogen and erythrocyte sedimentation rate were significantly improved compared to the placebo group.
The highest B concentration is found in bones, indicating one of the potential benefits in its ability to protect humans from osteoporosis. . The changes in bone structure and formation induced by boron deprivation might be a risk factor for osteoporosis. Six months of supplementation with calcium fructoborate (226 mg/d) incorporated into margarine was found to improve bone density in 66 of100 patients with osteoporosis (14). This finding resulted in the suggestion that calcium fructoborate may be a good adjuvant in the treatment of osteoporosis.
Findings showing that nutritional intakes of boron have beneficial effects on the central nervous system are among the most supportive of the suggestion that boron is a beneficial trace element for humans.
Low dietary boron has been shown to result in significantly poorer performance on tasks emphasizing manual dexterity, eye-hand coordination, attention, perception, encoding and short-term memory, and long-term memory. Collectively, the data from these studies indicate that B may play a role in human brain function and cognitive performance (15)..
Under well-controlled dietary conditions, boron supplementation (3 mg/d) to older men and women after consuming diets providing about 0.25 mg boron/2000 kcal for about 63 days altered electroencephalograms (EEG) such that there was a shift toward less activity in the low frequencies and more activity in the high, dominant frequencies of the EEG spectrum (3,4). Increased low-frequency activity is typical of states of reduced behavioural activation and has been associated with reduced performance in psychomotor tasks. Decreased high-frequency activity has been associated with impaired memory performance. Subjects supplemented with boron after deprivation exhibited improved psychomotor skills of motor speed and dexterity, and cognitive processes of attention and short term memory (3,4).
Limited evidence suggests that boron can facilitate insulin action (16).
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Keywords:-boron, arthritis, osteoporosis, cognitive function, diabetes