Boron is a naturally occurring trace element widely distributed throughout the environment in rocks, soil, and water. This metalloid is readily absorbed by plants, making the diet the primary source of human exposure. While not universally classified as an essential nutrient, scientific interest in boron’s role in human biology has grown. Boron, consumed in small amounts, influences various physiological systems.
Understanding Boron’s Role in the Body
Boron acts as a biologically active trace element that influences a number of metabolic pathways. Its primary function involves regulating the body’s use of other significant minerals. Specifically, boron affects the metabolism of calcium, magnesium, and phosphorus, which are important for skeletal health. This trace element also influences the activity of vitamin D and the concentration of steroid hormones, including estrogen and testosterone. By modulating these hormones, boron plays a part in bone density maintenance and overall bone strength.
Abundant Dietary Sources
The most reliable way to obtain this trace element is through plant-based foods, as the boron content of a crop is directly related to the soil in which it was grown. Certain fruits and vegetables are known to be particularly rich sources. Dried fruits, such as prunes and raisins, are highly concentrated, with a quarter-cup of prunes providing approximately 1.44 milligrams.
Nuts and legumes also contribute significantly to boron intake; almonds and peanuts are notable examples. While the concentration in a single serving may be lower, foods consumed in large quantities, such as coffee, milk, and potatoes, often become top contributors to the average daily intake.
Boron in Water and Supplements
Beyond solid foods, drinking water can provide a variable amount of boron depending on its source and geographic location. Water concentrations can fluctuate dramatically, ranging from a fraction of a milligram to over 100 milligrams per liter in certain regions. Arid areas often have higher concentrations of boron.
For individuals who struggle to meet their intake goals through diet alone, boron is available in dietary supplements. These supplements contain different chemical forms, such as sodium borate, boron citrate, or calcium fructoborate, and typically range from 0.15 to 6 milligrams of elemental boron per serving.
Guidelines for Intake and Safety
The average daily boron intake for adults typically falls within the range of 1 to 3 milligrams. While there is no official Recommended Dietary Allowance (RDA), a sufficient intake is generally achieved by consuming a diet rich in fruits, vegetables, nuts, and legumes. For safety purposes, a Tolerable Upper Intake Level (UL) has been established for adults at 20 milligrams per day. Toxicity is generally a concern only when taking high-dose supplements. Consuming amounts significantly above the UL can lead to adverse effects, including gastrointestinal issues like nausea, vomiting, and diarrhea.