Boron affects calcium metabolism, and a link between boron deficiency and arthritis has been suggested.¹ Although people with osteoarthritis have been reported to have lower stores of boron in their bones than people without the disease, other minerals also are deficient in the bones of people with osteoarthritis.² One double-blind trial found that 6 mg of boron per day, taken for two months, relieved symptoms of osteoarthritis in five of ten people, compared with improvement in only one of the ten people assigned to placebo.³This promising finding needs confirmation from larger trials.

Boron supplementation at 3–9 mg per day may be beneficial, particularly in treating people with juvenile RA, according to very preliminary research.⁴ The benefit of using boron to treat people with RA remains unproven.

Boron supplementation has been reported to reduce urinary loss of calcium and magnesium in some,⁵ but not all,⁶ preliminary research. However, those who are already supplementing with magnesium appear to achieve no additional calcium-sparing benefit when boron is added.⁷ Finally, in the original report claiming that boron reduced loss of calcium,⁵ the effect was achieved by significantly increasing estrogen and testosterone levels, hormones that have been linked to cancer risks. Therefore, it makes sense for people with osteoporosis to supplement with magnesium instead of, rather than in addition to, boron.

One trial studying postmenopausal women combined hormone replacement therapy with magnesium (600 mg per day), calcium (500 mg per day), vitamin C, B vitamins, vitamin D, zinc, copper, manganese, boron, and other nutrients for an eight- to nine-month period.⁹ In addition, participants were told to avoid processed foods, limit protein intake, emphasize vegetable over animal protein, and limit consumption of salt, sugar, alcohol, coffee, tea, chocolate, and tobacco. Bone density increased a remarkable 11%, compared to only 0.7% in women receiving hormone replacement alone.