Boron
Boron is a trace element that appears to affect how the body uses calcium, magnesium and vitamin D, though it is not proven essential for people. There is no daily target, and it comes from plant foods such as fruit, nuts and legumes, plus coffee and milk.
No set daily amount
20 mg a day at most for adults (US)
Upper limit · 10 mg a day in the EU, half the US limit; boron is not proven essential
- Richest per serving 1.43 mg in a cup of prune juice
- Main sources Fruit and nuts then legumes and coffee
- Animal foods Little meat and fish are poor sources
- Evidence Thin a few small human studies
Upper limits from the US National Academies and EFSA, food figures from the NIH Office of Dietary Supplements. The Caltide food library does not measure boron yet.
Food Sources of Boron
The Caltide food library does not measure boron yet, so there is no ranking here. Plants are the source, and how much they hold depends on the soil and water where they grew.
Foods Rich in Boron per Serving
- Prune juiceabout 1.43 mg in 1 cup
- Avocadoabout 1.07 mg in half a cup, cubed
- Dried and fresh fruitraisins, peaches, apples, pears and grape juice
- Nuts and legumespeanuts, peanut butter and beans
Main Sources of Boron in US Diets
In US diets the largest contributors are coffee, milk, apples, dried beans and potatoes. Coffee and milk are low in boron per cup, but people drink so much of them that they add up to more than richer foods eaten rarely.
Sources: NIH Office of Dietary Supplements, EFSA. Not medical advice.
What Is Boron?
Boron sits in an odd place in nutrition. Plants cannot live without it: it links the molecules of their cell walls, and boron-poor soil stunts crops. For people, no one has shown a disease caused by too little boron, so it has no daily amount, yet it clearly does things in the body.
What Boron Seems to Do
Studies in people and animals point to effects on how the body handles calcium, magnesium and vitamin D, all central to bone. Boron also appears to influence steroid hormones such as estrogen and testosterone, and markers of inflammation. How it does any of this is not known, and its exact biochemical role in people is still unclear.
About 85% to 90% of the boron in food and supplements is absorbed, and the body removes it mainly in urine.
What Human Studies Show About Boron
The research is small. A handful of trials have tested boron supplements for bone density, osteoarthritis, hormone levels and brain function, most with few people and short follow-up. Some found changes, others found none, and none was large enough to set advice. The NIH fact sheet concludes that more research is needed.
Boron Supplements
Boron is sold alone and in bone and joint products as sodium borate, boron citrate, boron glycinate or calcium fructoborate, and labels give elemental boron in mg. Since there is no daily need, there is no target to supplement toward, only the upper limit to stay under.
Boron Upper Limits in the US and EU
The US and EU limits for boron differ twofold. Both come from the same kind of animal studies on reproduction and development; the EU limit is 10 mg a day against 20 mg in the US. Either way, food alone does not come close for most people.
Common Boron Mistakes
Boric acid is a supplement. Boric acid and borax are pest killers and cleaners. Swallowing them causes poisoning: vomiting, diarrhea, red skin and, at high doses, seizures.
No daily need means none is needed. It means the case is not proven. A diet with plenty of fruit, nuts and legumes supplies boron either way, without a pill aimed at an unset target.
Tracking Boron in Caltide
- Not totaled yetCaltide does not add up boron yet, because most food data does not measure it.
Boron Sources and References
The figures and claims on this page are checked against these sources.
Questions About Boron
No daily amount has been set. Boron is not proven essential for people, so there is no RDA, adequate intake or EU label reference, only upper limits.
Fruit, nuts and legumes. In the NIH table, a cup of prune juice has about 1.43 mg and half a cup of avocado about 1.07 mg. Raisins, peaches, apples, pears and peanuts are also good sources.
Yes. Adults should stay under 20 mg a day in the US and 10 mg a day in the EU, from food and supplements together.
There is not enough evidence to say. Boron appears to affect how the body uses calcium, magnesium and vitamin D, and a few small studies have looked at bone and osteoarthritis, without firm conclusions.
Not reliably. A few small studies found shifts in testosterone or estrogen with boron supplements, and others found none, so it is not an established effect.
It is a boron compound, but not a food. Swallowing boric acid or borax, sold as pest killers and cleaners, can cause poisoning with vomiting, diarrhea, red skin and in severe cases seizures.
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