The Bone and Joint Benefits of Boron

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The oft neglected trace mineral and its importance for bone and joint health

Meet boron, atomic number 5, “a dynamic trace element affecting an exceptionally large number of seemingly unrelated biological functions,” according to a 2017 review.[1] Despite this broad statement of the importance of boron for potentially every system in the body, study data points strongly at the importance of this mineral for bone and joint health.

Boron, osteoporosis, and steroid hormones

Among its many functions in the body, boron is best known for its protective effects on bone. It impacts not only the body’s calcium and magnesium stores, but also vitamin D and hormone metabolism.[2],[3]

Boron supplementation has been shown to increase bone strength in animal studies, while boron deficiency leads to impaired growth and abnormal bone development.[4],[5] Boron supplementation also alleviates some of the effects of vitamin D deficiency in animals, encouraging normal bone growth despite this deficiency.[6] A mechanistic study provided evidence that boron regulates the expression of genes related to tissue mineralization and the actions of key hormones (17β-estradiol, testosterone, and vitamin D) involved in bone growth and turnover.[7]

The risk of osteoporosis (low bone density) increases in women after menopause, in large part due to nutritional and hormonal influences. Thankfully, supplementation of 3 mg of boron daily has been shown to reduce the loss of calcium, magnesium, and phosphorus (nutrients important for bone integrity) in post-menopausal women.[2] Boron supplementation reduced calcium losses by 52 mg/d when the women were low in magnesium, and by 22 mg/d when magnesium levels were adequate. In the same study, boron also significantly increased blood concentrations of estradiol (the most potent form of estrogen in the body) and testosterone, both of which are important for strong bones, particularly with aging. Similar effects on hormone levels have also been seen in men.[8]

Calcitonin (a hormone that decreases calcium levels) has been found to be elevated in women with postmenopausal osteoporosis.[9] Boron supplementation at 3 mg daily lowered serum calcitonin levels in post-menopausal women, while increasing blood levels of calcium and vitamin D,[10] thus protecting the bones. In a year-long study, postmenopausal women consuming ten boron-rich prunes daily (equalling 3-4 mg/day of boron), along with calcium and vitamin D supplements, were found to have improved bone mineral density.[11]

Boron in osteoarthritis

Boron can benefit not only the bones, but also the joints. Serum boron levels are significantly lower in osteoarthritis patients, and lower levels are correlated with disease severity and duration. In fact, arthritic bones have been shown to contain an average of a mere three parts per million (ppm) boron compared with 56 ppm boron in healthy bones.[12] In areas of Australia where water and soil levels of boron are high, the incidence of musculoskeletal diseases such as osteoarthritis is half that of areas where levels of boron are low.[13]

In a recent study, serum boron levels were assessed and compared to inflammatory markers, disease duration, and disease severity in patients with osteoarthritis of the knee.[14] Boron levels were significantly lower in individuals with osteoarthritis than in healthy controls, and the levels were correlated with disease duration and severity. In a placebo-controlled pilot study of patients with osteoarthritis, 6 mg of boron daily improved symptoms in half the patients taking boron, while only one of those taking the placebo (10%) had improvements after 8 weeks of supplementation.[15]

Boron inhibits inflammation

Severe inflammation leads to the release of enzymes called proteases, which worsen inflammation by breaking down connective tissue.[16] In fact, rheumatoid arthritis (RA) has been described as an illness of uncontrolled proteolysis (protein breakdown).[17] Boron reversibly inhibits the activity of a class of inflammatory proteases called serine proteases.[18],[19] Boron also appears to inhibit other inflammatory molecules and modulate immune function, supporting a less inflammatory state.[20] It has even been shown to improve periodontal disease (disease of the gums and other structures around the teeth) in animals, reducing inflammation and bone loss.[21]

Boron in rheumatoid arthritis

Serum boron levels have been observed to be significantly lower in individuals with RA than in age-matched controls.[22] Patients with low boron levels are more likely to have high levels of rheumatoid factor (RF), the antibody that causes destruction of the joints in RA. In a double-blind randomized placebo-controlled study, 80 patients with RA were supplemented with 6 mg of elemental boron daily for 60 days as an adjunct to the RA drug etanercept.[23] Supplemental boron significantly improved the clinical scores, and also decreased serum levels of several inflammatory markers, including tumor necrosis factor-α (TNF-α).

Rationale for boron supplementation

Boron is found in fruits, vegetables, legumes, nuts, avocados, and other foods. However, boron intakes in the U.S. vary enormously, from about 0.3-41 mg per day. The broad range of intakes is due to variable soil content and conditions, and the use of phosphate and potash fertilizers, which inhibit boron absorption in plants.[24],[25] Research suggests that a significant number of people do not regularly consume more than one mg of boron a day, which could be of clinical concern.[26]

There is no established, recommended dietary intake for boron, even though a substantial body of research demonstrates it is likely an essential micronutrient.[27] For these reasons, and in light of the studies discussed herein, consideration for boron supplementation, particularly for individuals with concerns of osteoporosis and arthritis, should be given.

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