Boron, that wonderful element that sits right next to carbon in the periodic table, is one millionth in abundance compared to carbon, in the universe. On Earth, while the difference in abundance is less dramatic and varies depending on whether you’re looking at the oceans, or the crust, or plain old soil, boron still lags in abundance compared to its neighbor carbon. In the human body, the boron:carbon ratio is the most dramatic, which is perhaps why few people are aware of the importance of boron in physiology.
Boron’s essential role in plant physiology was recognized in the last century, in 1923. It is the most common micronutrient deficiency in plants across the world, and timely application of boron supplements to the soil can rescue crops without significant financial loss. Although all plants appear to require boron for multiple processes including protein synthesis, development of cell walls, carbohydrate metabolism, sugar transport, pollen growth, and seed production, the requirement varies across the plant kingdom. Cruciferous vegetables such as broccoli, cabbage, cauliflower, and leafy vegetables like spinach, have the highest requirement of boron; beans and peas on the other hand have very low requirements of boron for maintaining healthy growth. Like most things, the concentration is important and too much boron can also be toxic to a plant.
The role of boron in human physiology continues to be explored after first being recognized in the 1970s. Thus far, boron’s role has been observed in the regulation of many enzymes ultimately influencing processes as diverse as bone health, and wound healing. Substantial evidence has been collected to show that boron is beneficial, if not essential to human health and well-being.
In the early 1980s, studies on animals showed that boron reduced inflammation which occurred as a consequence experimentally induced arthritis. Subsequent double-blind human studies were conducted, with the same results based on subjective measures. What is more, in a limited separate study, providing about 6 mg/day of boron in the form of calcium fructoborate, a naturally occurring form of boron in fruits and vegetables, alleviated joint rigidity in 80% of participants in the study. Red apples have the highest amount of calcium fructoborate - almost 2.5 mg/kg; broccoli florets have 1.85 mg/kg.
Buoyed by the results from the calcium fructoborate (CFB) study, a subsequent larger double-blind studied the effect of different doses of CFB - participants were given either 3, 6, or 12 mg CFB each day, for 15 days. The findings were provocative - at the end of the study, inflammatory biomarkers like C-reactive protein (C-RP) and tumor necrosis factor α (TNF-α) were reduced, and a dose of 3 mg/day yielded the best results. Other studies report similar results, as well as reduced levels of LDL-cholesterol, although with 112 mg/day CFB. These levels are 200 times lower than the toxic level for ingested boron - 20 g/day.
Results from animal studies, as well as studies on single cells, have suggested that boron might play a role beyond that of reducing inflammation. They implicate boron in proper bone formation; facilitating some neuronal functions; and inhibiting growth of cancer cells. One might be tempted to speculate that there is some grand unifying mechanism for the action of boron, and perhaps there is one, but it is currently not yet entirely clear.
Too much boron though, can be toxic - more than 20 g/day. It’s impossible to get too much boron from foods that are rich in boron, but excessive use of boron supplements can cause skin irritation, irritability, tremors, weakness, headaches, depression, diarrhea, vomiting. A comparison of the effectiveness of boron supplements illustrated that calcium fructoborate, the form found in plants, was utilized better than sodium tetraborate (also marketed as borax, and sodium borate).
Etanercept (trade name Enbrel) is a drug prescribed for arthritis. According to a recent study, the effectiveness of this drug was enhanced when given with boron supplements, with calcium fructoborate being the most effective enhancer. The drug Velcade (commonly called bortezomib) was developed to treat multiple myeloma, a cancer that forms in a type of white blood cell called a plasma cell. However, after animal studies it was found to also reduce inflammation caused by arthritis, and it is now prescribed to some patients with arthritis. It is possible that some of the anti-inflammatory effect of bortezomib is a consequence of the boron (hence “bor”-tezomib) that is an integral element of the drug.
Boron’s importance goes beyond its role in plant and human physiology; it is also used in the manufacture of many household products, including detergents and insecticides; in the manufacture of glass; and even as a rocket fuel igniter. Boron, some chemists might say, is a many-splendoured element!