Boron is a trace mineral found naturally in the environment and various foods. Although not yet classified as an essential human nutrient, evidence suggests it plays a supportive role in numerous bodily processes. This includes its involvement in bone development and maintenance, as well as influencing the metabolism of certain hormones like estrogen and testosterone. Boron also appears to affect the body’s use of other minerals such as calcium, magnesium, and phosphorus. It is linked to functions like wound healing, brain activity, and immune responses.
Dietary Boron Intake and Sources
For most individuals, the primary source of boron is their daily diet, particularly from plant-based foods. Average daily dietary intake for adults in the United States typically falls within a range of 0.87 to 1.35 milligrams per day, with vegetarians often having higher intakes due to their diet rich in plant foods.
Common food sources include prune juice (1.43 mg per cup), avocado (1.07 mg per half cup), raisins (0.95 mg per 1.5 oz), peaches (0.80 mg per medium fruit), and apples (0.66 mg per medium fruit). Peanuts, beans, coffee, and wine also contribute to overall boron consumption.
Common Supplemental Dosages
While there isn’t a universally recommended daily allowance for boron, common supplemental dosages for general health maintenance often fall within a range of 1 to 3 milligrams per day. The amount of elemental boron in dietary supplements typically ranges from 0.15 to 6 milligrams.
Higher therapeutic dosages have been explored for specific health purposes, though these should always be considered under the guidance of a healthcare provider. For instance, research indicates that supplementing with 3 milligrams of boron per day may help support bone health and maintain bone mineral density, particularly in postmenopausal women.
Studies on osteoarthritis have utilized dosages of 3 to 6 milligrams per day, with some trials showing reduced knee pain at 6 milligrams per day over two weeks. Boron also influences hormone regulation, and supplementation has been shown to potentially increase levels of estrogen and testosterone. In studies investigating hormonal changes, doses of 10 milligrams have been used. While research suggests these benefits, more comprehensive studies are still needed to fully confirm the efficacy and optimal dosages for these specific conditions.
Tolerable Upper Intake Level and Safety
To ensure safety, the Food and Nutrition Board has established a Tolerable Upper Intake Level (UL) for boron. For adults aged 19 and older, including pregnant and lactating women, the UL is set at 20 milligrams per day. The UL represents the maximum daily intake level that is unlikely to pose a risk of adverse health effects for most healthy individuals.
Consuming boron in excess of this limit, especially from high-dose supplements, can lead to side effects. These can include nausea, vomiting, diarrhea, headaches, and skin irritation. In rare and extreme cases, very high doses, such as 15,000 to 20,000 milligrams, have been reported to be fatal in adults.
Boron toxicity is exceedingly rare from food sources; the risk of adverse effects is almost exclusively associated with high-dose supplementation. Individuals with pre-existing kidney disease or hormone-sensitive conditions, such as certain cancers, should avoid boron supplements or use them only under strict medical supervision due to potential interactions or exacerbation of conditions.