Boron: the trace element explained

Iron, zinc, selenium – almost everyone knows those. But boron? This trace element rarely takes centre stage, even though we encounter it every day through apples, nuts and legumes. Boron is a natural trace element and metalloid that enters the diet via plant-based foods; for humans it is regarded as non-essential, and no classic deficiency picture is defined. This guide explains factually what boron is, which foods contain it, in what forms it is offered as a food supplement, and what you can look out for in terms of amount and quality.

The key points at a glance

• Boron is a trace element and metalloid, widely distributed in nature.
• For humans it is regarded as non-essential – no classic deficiency picture is defined.
• Good sources are fruit, nuts, legumes and some vegetables.
• In supplements, boron is often present as boron citrate, boron glycinate or sodium borate.
• Typical amounts are in the milligram range per day.

What is boron – and what role does it play in nature?

Boron (chemical symbol B) is a metalloid and one of the trace elements – that is, substances that occur in the body only in tiny amounts, if at all. In nature, boron never appears in pure, elemental form, but always as a compound, such as a borate or boric acid. It is a natural component of soils, groundwater and seawater and reaches plants through their roots. For plants, boron is in fact an essential nutrient that they need for normal growth – which is why farmers know it as a fixed part of plant nutrition.

In humans, the role of boron is less clearly defined than that of the established trace elements. It is currently not regarded as essential, because no clear deficiency picture is defined – you do not become ill if you take in no additional boron. Nevertheless, boron is repeatedly the subject of nutritional research, which is why it is receiving increasing attention.

Which foods contain boron

Boron enters the diet primarily via plant-based foods. The content depends strongly on the boron content of the soil on which the plants were grown, and therefore varies from region to region. The following are considered comparatively rich in boron:

A plant-focused diet with plenty of fruit, nuts and legumes therefore supplies boron regularly and quite automatically. Animal-based foods such as meat or dairy products, on the other hand, usually contain considerably less. Anyone who eats a varied, plant-rich diet generally does not need to worry about their boron intake – a point that also comes through in the guide Nutrients when you eat little vegetables.

The regional aspect is also interesting: because the boron content of a fruit depends directly on the soil, the same apple can contain different amounts of boron depending on where it was grown. A fixed table with exact milligram values per food would therefore be misleading – the range is simply too wide. As a rule of thumb: eat a varied, plant-focused diet, and boron will come together in a sensible amount all by itself through the range of fruit, nuts and legumes.

Forms of boron in food supplements

In supplements, boron is offered in various chemical compounds that differ in their pure boron content. Common ones are:

• Boron citrate: boron bound to citric acid or citrate.
• Boron glycinate (boron bisglycinate): boron bound to the amino acid glycine.
• Sodium borate / sodium tetraborate: a mineral boron compound.

Because boron is supplied only in very small amounts, the precise declaration of the elemental boron content – that is, the pure amount of boron, not just the compound – is especially important. How the chemical form can influence absorption in the body is put into general context by Bioavailability simply explained.

Amount, upper limits and a sensible framework

The amounts common in food supplements are in the milligram range per day – and thus considerably lower than for some other minerals. For boron, the European Food Safety Authority (EFSA) has derived a tolerable total intake level (Upper Level, UL) for adults that lies clearly above the usual intake amounts from a normal diet. Important: this upper limit refers to the total intake from all sources combined – foods, beverages and supplements. Anyone using food supplements should therefore observe the manufacturer's dosage instructions and not carelessly combine different sources, in order to stay within a sensible framework. The general topic of overdosing is put into context by Can you take too many vitamins?.

What research is investigating

Boron is an active field of nutritional research, precisely because its status in humans is more open than that of established trace elements. Among the things being investigated are how boron is absorbed and excreted in the body, what interactions it has with other minerals such as calcium and magnesium, and what role it might play in mineral metabolism. For plants, the essential function of boron is well documented; in humans, the data are thinner and continue to be researched.

To put it honestly: for boron, no health claims (health claims under Regulation (EU) No 432/2012) are currently authorised in the EU. We therefore may not and do not wish to make statements about a particular effect – for example on bones, joints or the hormonal balance. We describe boron in terms of what is established: its occurrence, the forms and the questions of dosage.

Why boron is often mentioned alongside bones and joints

Anyone who looks into boron quickly comes across its association with bones, joints and mineral metabolism. Where does that come from? In the discussion, boron is frequently mentioned in connection with other minerals such as calcium, magnesium and vitamin D, because research is investigating possible interactions between these substances. This has given rise to a thematic proximity – boron often appears in guides and product ranges next to the classic "bone nutrients".

The clean distinction is important: this association describes in what context boron is discussed – it is expressly not a promise of effect. The nutrients responsible for the actually authorised statements around bones are others, such as calcium, vitamin D, magnesium or vitamin K. If this topic interests you, our neutrally worded guides on Nutrients for the bones and Nutrients for the joints give you a suitable overview.

What you can look out for regarding quality

• Form: a clear statement of the compound (e.g. boron citrate, boron glycinate, sodium borate).
• Elemental boron content: a stated pure boron proportion per daily portion.
• Purity: laboratory-tested, without unnecessary additives – see Laboratory-tested: what does that mean?
• Transparent dosage: sensible, clearly declared amounts in the milligram range.

Anyone who wants to read the label with confidence will find a practical guide in Food supplements: reading the label correctly. As a German manufacturer with laboratory testing, Scheunengut places value on transparent declaration and tested raw materials.

Honestly put into context: what is established and what is not

Established is: boron is a natural trace element that enters the diet via plant-based foods, is essential for plants and is supplied to humans in the milligram range. Open – or not assertable – is a concrete health effect in humans; there are no authorised statements on this in the EU, and no classic deficiency picture is defined. Boron is often mentioned in connection with bones and joints; that is an association arising from the discussion, not a promise of effect. For health questions or persistent complaints, please consult your doctor.

Suitable products from Scheunengut

You will find boron and other trace elements in the category Trace elements as well as in the overview under Vitamins, minerals & trace elements. Since boron is frequently mentioned in connection with bones and joints, the section Joints & bones also fits. As further, neutrally worded guides, Nutrients for the bones and Nutrients for the joints are worthwhile.

Frequently asked questions (FAQ)

Is boron essential for humans?

According to current knowledge, boron is regarded as non-essential in humans – no clear deficiency picture is defined, so you do not become ill if you take in no additional boron. For plants, on the other hand, boron is an essential nutrient. Boron is the subject of nutritional research and continues to be investigated.

Which foods contain the most boron?

Boron is found above all in plant-based foods: fruit such as apples, pears, grapes, plums and raisins, nuts such as almonds, hazelnuts and walnuts, as well as legumes. Wine and some mineral waters also contain boron. The content varies depending on the boron content of the soil. Animal-based foods usually supply considerably less.

How much boron per day is safe?

The amounts common in food supplements are in the milligram range per day. EFSA has derived a tolerable total intake level (Upper Level) for adults that refers to all sources combined – foods, beverages and supplements. Stick to the manufacturer's instructions and do not carelessly combine sources.

In what form is boron available as a food supplement?

Common ones are boron citrate (bound to citrate), boron glycinate or boron bisglycinate (bound to the amino acid glycine) and sodium borate as a mineral compound. What matters is the statement of the elemental boron content, that is, the pure amount of boron per daily portion, not just the compound.