What Is Boron?
Boron is a metalloid element with atomic number 5. It is relatively rare and never appears on Earth in its pure form. Instead, boron is found in compounds like borax, boric acid, kernite, ulexite, and colemanite .
Many nutritionists do not consider it an essential nutrient (even though it is essential for growth and positively affects health) because it does not have a “defined biochemical function.” Recent research has found that boron is important for immune function, bone health, brain health, and hormone production, but there is no recommended intake [2, 3, 4].
- Important for bone, brain, and reproductive health
- May be useful for passing kidney stones
- Dietary intake may help prevent arthritis
- Easy to get enough from the diet
- Toxicity is rare
- Possible toxicity at high doses
- May interfere with thyroid function
- Not enough research to identify a recommended intake
Deficiencies of any important nutrient will cause health problems, and these problems can help us understand the nutrient’s normal function. Because there is no official recommended intake of boron, it is difficult to identify or assign symptoms to boron deficiency.
According to some researchers, boron deficiency may cause problems with bone development, growth, and healing. When people don’t have enough boron, their bone cells can’t lay down new bone tissue properly, which may lead to bone diseases like osteoporosis and rickets .
Boron metabolism appears to vary between families: according to one analysis, relatives tend to have much more similar levels of boron in their blood than unrelated individuals. However, they also tend to live in similar environments with similar amounts of boron in their diets. Researchers have yet to identify the genes that manage boron metabolism [5, 6].
Metabolic Functions of Boron
Researchers are investigating the role of boron as an ultratrace element and how it contributes to human health. Evidence suggests that boron is important for the following functions, but these are not necessarily grounds to supplement with boron. Talk to your doctor or nutritionist to determine if your diet may be deficient and if supplements or diet changes may be appropriate for that reason.
1) Bone Health
Boron prevents the breakdown of vitamin D and increases the amount of available vitamin D in the body. Because vitamin D is essential for skeletal health, boron is also important to maintain strong bones .
One study found that the bones of people taking boron supplements were much more resistant to cutting than those of people not taking supplements. Boron supplements also increased the mineral density of female athletes’ bones [7, 8].
2) Wound Healing
Boron seems to be important for healing wounds. It may participate in the production of fibrous proteins like collagen and other compounds that help repair damage to skin, bones, and other tissues .
A gel containing boron is under investigation in the healing of diabetic foot ulcers. The gel killed microbes like yeast and fungi and significantly sped up the process of wound repair and tissue growth in a laboratory setting .
Animals fed diets high in boron experienced faster and better quality wound healing .
3) Sex Hormones
Testosterone and estrogen are considered the two most important sex hormones. They are often called the male and female sex hormones, respectively, although each has many functions in both men and women [13, 14].
Testosterone, the “male sex hormone,” has a seemingly endless list of functions. It determines the sex of a baby in the womb. It drives puberty in boys. It is a steroid that builds muscle. It coordinates sexual drive. It improves memory and cognition – and more .
Low testosterone is much more serious in men than in women, largely because men have higher levels of testosterone by default. Low testosterone can cause weakness, fatigue, depression, sexual dysfunction, decreased muscle mass, anemia, bone disease, facial and body hair loss, and insomnia .
After one week of daily boron supplements, eight healthy men had significantly increased testosterone in their blood. According to the authors, boron may deactivate a protein called sex hormone binding globulin (SHBG), which was significantly lower in these men only six hours after their first boron supplement [4, 15].
Boron supplements also significantly increased testosterone in postmenopausal women. This effect was most dramatic when the women’s diets were low in magnesium. Testosterone is sometimes used to treat sexual dysfunction in women after menopause, but only if these women also have high enough levels of estrogen [16, 4, 17].
Estrogen, the “female sex hormone,” is vital for both men and women, though estrogen levels are much higher in women. Estrogen drives puberty for girls and determines sexual behavior in women. In men, estrogen is important for sexual development and healthy sperm [18, 19, 20].
Abnormally high or low estrogen levels can both cause health problems. High estrogen may increase the risk of cancer or stroke; low estrogen, especially in women, may cause memory problems, irregular menstrual cycles, bone disease, and depression [25, 26, 27, 28, 29, 30, 31].
After menopause, estrogen levels drastically fall. As a result, women are susceptible to many of the above risks during this period of their lives .
Boron may or may not directly interact with (and raise) estrogen levels. One study of postmenopausal women showed a significant increase of estrogen in the blood, while other studies have shown decreased estrogen after supplementing boron [16, 33].
Rather than directly acting on estrogen, boron may increase the body’s sensitivity to estrogen. It may bind to and enhance one type of estrogen receptor called estrogen receptor beta, or ER-β. ER-β is important for the health of the uterus, immune system, gut, lungs, and prostate, and it may help the body fight cancer [4, 34, 35, 36, 37, 38].
Follicle Stimulating Hormone
Both high and low levels of FSH can cause health problems. Diseases and conditions that feature low FSH include polycystic ovarian syndrome (PCOS), hypopituitarism, and hyperprolactinemia [41, 42, 43].
Limited evidence suggests that boron may increase FSH. However, this has only been studied in rats exposed to toxic levels of boron. The rats also lost the function of sexual organs and developed decreased fertility .
4) Brain Health
When boron is deficient in both animals and people, brain activity decreases. People with extremely low boron levels had a shorter attention span and weaker short-term memory. They also scored lower on tests measuring dexterity and coordination .
These changes in brain activity are similar to those caused by malnutrition and heavy metal poisoning .
Boron is undoubtedly important for a healthy brain. Some researchers have recommended boron supplements for those who may be deficient .
Possible Benefits of High Boron Intake
Some clinical studies suggest that high boron intake may have certain health benefits, but more research is required in order to determine exactly when supplementation is appropriate. Talk to your doctor or nutritionist to determine if your diet may be deficient and if supplements or diet changes may be appropriate for that reason.
Estimated rates of arthritis have been negatively correlated with dietary boron. In areas of the world where boron intake is 1 milligram or less per day, arthritis rates range from 20 – 70%. In areas of the world where boron intake is 3 – 10 milligrams, arthritis rates range from 0 – 10% .
People with arthritis also have lower concentrations of boron in their joints than people without arthritis .
In a study of twenty people with arthritis, half reported improved symptoms on a 6 mg/day boron supplement. Only 10% of people receiving placebo reported improvements .
6) Kidney Stones
Kidney stones are crystallized solids that form in the kidney. If they grow too large, they can cause severe pain, vomiting, and bloody urine. In combination with antioxidants, hydration, and diet, boron may help flush kidney stones [45, 46, 47].
10mg/day increased the rate of kidney stone excretion in a small human trial. Those who took the boron supplements also felt less pain when the stone passed .
Boron in Medicine
Boron has also proven useful for certain medical applications and avenues of research. Note that the applications in this section have absolutely no bearing on boron as a supplement or even a nutrient. Do not attempt to apply any of these therapies without the supervision of a doctor.
Boric Acid for Yeast Infections
Yeast is often part of the vaginal flora; that is, its presence in the vagina is normal and won’t cause problems most of the time. Sometimes, however, the yeast grows too much and too fast. This results in a yeast infection also called vaginal thrush .
However, boric acid has largely been replaced by safer and more effective drugs and remedies for vaginal yeast infections. Talk to your doctor about alternatives before attempting to use a boric acid suppository.
Importantly, regular boron supplements don’t contain boric acid. As a result, they won’t have any effect on vaginal yeast infections.
Cancer Research & Advances in Treatment
Prostate-specific antigen, or PSA, is a protein found in the human prostate. In the early stages of prostate cancer, PSA increases the amount of the tumor-promoting insulin-like growth factor 1, or IGF-1, in the prostate. Boron supplements may decrease the amount of PSA in the prostate, suggesting a possible role in prostate cancer prevention [54, 4].
Additional research is required to determine the role of boron in tumor development.
Targeted Boron Therapies
Some targeted, cutting-edge boron therapies are used to treat cancer. However, these effects don’t apply to dietary boron supplements.
This drug disrupts important mechanisms inside cells and sensitizes them to apoptosis, or cell suicide. It acts on cellular proteins which are far more active in cancer cells than in normal, healthy cells; as a result, cancer cells die at much higher rates than healthy cells .
Because bortezomib sensitizes cancer cells to apoptosis, it can also improve the effectiveness of other chemotherapy drugs like cisplatin .
Boron Neutron Capture Therapy
Boron neutron capture therapy, or BNCT, is a 21st-century cancer treatment that destroys cancer cells without killing surrounding healthy cells. After surgery to remove as much of the tumor as possible, doctors administer boron compounds that target the cancer cells. Then, the patient receives a radiation treatment that reacts with the boron and destroys the tumor [58, 59, 60, 61].
This type of treatment can even be used against cancers that can’t be operated, such as brain tumors .
Cell Research on Heavy Metal Poisoning
Many heavy metals including arsenic, cadmium, mercury, and lead are highly toxic and can cause serious damage to a person’s DNA after exposure. Some boron compounds, such as borax and boric acid, prevented DNA damage from heavy metals in cell-based studies [4, 62].
Importantly, however, dietary boron supplements have not produced these effects.
As mentioned, boric acid is poisonous. Borax can also have toxic effects. Neither should be ingested – they are only meant to be used as antiseptic solutions .
Sources & Supplement Dosage
Boron intake from diet changes depending on where you live. In Europe, daily boron can be as low as 0.8 mg/day. In the United States, it can be as high as 7 mg/day .
The recommended upper limit per day for adults is 20 mg .
Most boron supplements contain 3mg/capsule and recommend taking one capsule daily.
- Red grapes, raisins, and red wine
- Peanuts and other nuts (hazelnuts, walnuts, almonds, etc.)
- Many fruits, including apples, pears, oranges, apricots, and currants
- Beans, peas, and lentils
- Some vegetables, including broccoli
Many more fruits and vegetables contain smaller quantities of boron. If you eat a significant amount of these foods, you probably don’t need a boron supplement .
Commercially available boron supplements usually come in capsules or as liquid drops, delivering between 2 and 6 mg of boron per serving, although 3 mg is the most common amount. Remember that, to stay on the safe side, adults should never take more than 20 mg of boron per day by mouth .
Boric Acid Suppository
Safety & Side Effects
Supplemental boron is likely safe in suggested amounts, even for sensitive groups such as children and pregnant women.
In dietary supplements, boron is usually derived from natural sources. Some forms include calcium fructoborate, calcium borogluconate, boron citrate, or boron complexes. It’s often combined into salts with calcium to achieve synergistic bone health benefits.
Boric acid is poisonous if swallowed and should never be taken by mouth. If you accidentally consume boric acid, call poison control and seek medical attention immediately .
Most examples of boron toxicity have involved a boron compound such as boric acid or borax. These are not found in dietary boron supplements.
Though boric acid poisoning is rare now, it was once a serious risk to infants. As recently as the 1980s, babies ingested boric acid or borax in formula or to soothe the pain of teething. Some of these babies suffered seizures and recovered; others died. Boric acid is much more dangerous to children than to adults [53, 69].
There is some evidence that boron may interfere with the thyroid gland.
Boron may compete with iodine in the thyroid, reducing the function of the gland. When the thyroid gland’s function is reduced, it grows larger to compensate. Over time, this growth forms a goiter. Boron, in rare cases and in large amounts, may contribute to goiter .
Borax in Food
Borax has been used as a preservative and food additive in food for over a century. Despite having been banned in many countries, borax is still used in others to improve the texture and appearance of caviar, noodles, and other gummy or gooey foods. Borax is toxic to the kidneys, brain, and reproductive system; it may also damage DNA and cause cancer [73, 74].
Avoid any and all foods that may contain borax. Watch for the initials E285: that’s the code for borax as a food additive .
Boron prevents the breakdown of vitamin D. In this way, it increases the amount of time that each molecule of vitamin D spends in the blood and, as a consequence, the total amount of vitamin D available to your body .
Most people have to worry more about vitamin D deficiency than vitamin D toxicity, but too much of a good thing can still be dangerous.
Supplementing with too much vitamin D can cause nausea, vomiting, diarrhea, constipation, bone pain, irregular heartbeat, and other symptoms. Always do your research before supplementing; avoid taking too much vitamin D and boron, especially together [75, 76].
To find the ideal balance of vitamin D and boron, talk to your doctor or nutritionist.
Boron is an ultratrace element: it is relatively rare and makes up a tiny amount of the human diet, but it is essential for bone, brain, and reproductive health. Boron deficiency, like vitamin D deficiency, causes problems with bone growth and healing. Dietary boron may also play a role in bone health, brain health, and hormone regulation.
Boric acid – a different form of boron than the ones found in dietary supplements – is also used as a suppository to treat yeast infections, although it’s not recommended. Many safer and more effective remedies exist.
However, boric acid is poisonous in large quantities and should never be taken by mouth.
Borax – also not found in supplements – is toxic to the kidneys, brain, and reproductive system, but it is still used as a food additive in some parts of the world; avoid foods with the code E285.
Most people probably don’t need to supplement with boron because it is readily available in many foods, such as fruits, nuts, beans, and peas. Some people already get up to 7 mg of boron from their diets, and doctors recommend no more than 20 mg per day.
Boron toxicity is rare because boron is easily passed in the stool and urine.
Some research suggests that boron may interfere with the thyroid gland; if you supplement with boron, make sure you also get enough iodine to prevent thyroid problems and goiter. Boron increases the potency of vitamin D; too much boron and vitamin D taken together may cause health problems.