Tolerable Upper Intake Levels for Boron
For healthy adults over 19, the established tolerable upper intake level (UL) for boron is 20 mg per day from all sources, including food, water, and supplements. The UL is the maximum daily amount that is unlikely to cause adverse health effects. For different age groups, the ULs are set lower to reflect differences in body weight and developmental stages, with specific recommendations for adolescents and children. It is important to note that the UL is not a recommended daily intake, but rather a safety ceiling. Most people get a lower amount of boron from their diet alone, ranging from 0.87 to 1.35 mg per day in the U.S.
Boron in Food vs. Supplements
Boron intake from food is generally considered safe and poses no health risks, even at higher consumption levels from a plant-rich diet. However, the risk for toxicity arises when supplementing with high doses, especially when exceeding the 20 mg UL. The concentration of boron in plant-based foods can vary depending on the boron content of the soil and water where they were grown, with arid regions generally having higher concentrations. Supplements, which often contain 3 to 6 mg of boron per capsule, should be taken with caution to avoid surpassing the UL.
Potential Benefits of Boron Supplementation
At appropriate supplemental doses, such as 3-6 mg per day, boron has been linked to several potential health benefits, particularly in areas like bone health and hormone regulation. It is thought to improve the body's use of key minerals like calcium and magnesium and support the metabolism of steroid hormones such as estrogen and testosterone. Studies also suggest that boron may have anti-inflammatory effects that could benefit individuals with osteoarthritis. For example, one study found that supplementing with 6 mg of boron daily for one week significantly increased free testosterone and decreased estradiol levels in healthy males. This illustrates boron's potential role as a hormone modulator.
Risks of Excessive Boron Intake
Exceeding the tolerable upper intake level for boron can lead to adverse health effects. Acute boron toxicity from accidentally ingesting large amounts of boric acid or borax has been documented, with symptoms including nausea, vomiting, diarrhea, and headaches. While dietary intake is unlikely to cause harm, consistently high supplemental doses over 20 mg per day may lead to chronic toxicity, which can impair male fertility and cause other issues. Individuals with kidney disease are at a higher risk of boron toxicity because their kidneys are less efficient at clearing excess boron from the body. Therefore, these individuals should avoid boron supplements unless specifically advised by a doctor.
Comparison of Boron from Food vs. Supplements
| Feature | Boron from Food | Boron from Supplements |
|---|---|---|
| Dosage Control | Less precise; depends on diet composition. | Precise; dosage is listed on the product. |
| Toxicity Risk | Extremely low; large quantities of food are required to approach the UL. | Higher; easier to accidentally exceed the UL, especially with high-dose products. |
| Additional Nutrients | Comes with a wide range of synergistic vitamins and minerals. | Provides a concentrated dose of boron with few or no other nutrients. |
| Effect on Hormones | Balanced and subtle; unlikely to cause significant shifts. | Can cause more noticeable and potentially rapid shifts in hormone levels. |
| Food Sources | Plant-based foods like fruits, nuts, legumes, and certain beverages. | Available as capsules, tablets, and liquid drops, often in forms like boron citrate or calcium fructoborate. |
Conclusion
For most healthy adults, consuming less than 20 mg of boron per day is considered safe. This amount is easily achieved through a balanced diet rich in fruits and vegetables, and typical boron supplements containing 3-6 mg can be safely incorporated. The risk of harm increases with excessive intake, especially from high-dose supplements, which can cause toxicity and potentially impact fertility. While boron offers several potential benefits for bone health and hormone balance, its supplementation requires caution, particularly for individuals with hormone-sensitive conditions or kidney issues. Always consult a healthcare professional before starting any new supplement regimen to ensure it is appropriate for your individual needs and to determine the correct dosage. For further reading on mineral intake and healthy eating, consult the official guidelines from the Office of Dietary Supplements at the National Institutes of Health.
