A trace element is a small mineral nutrient. It is necessary to the body, but it has to be supplied in small quantities. If ingested in too large quantities, it can be toxic.
We can distinguish:
- Essential trace elements at risk of deficiency demonstrated in humans: Iodine, Iron, Copper, Zinc, Selenium, Chromium, Molybdenum, (Fluorine*).
- Essential trace elements at low risk of deficiency : Manganese, Silicon, Vanadium, Nickel, Tin, (Cobalt*).
What are the functions of trace elements ?
Trace elements may have a structural role: for example, iron in haemoglobin, and iodine for thyroid hormones. Most of them help to activate all kinds of enzymes.
Finally, some trace elements contribute to antioxidant defences. Selenium, zinc, copper, iron and manganese are part of the group of antioxidants. To neutralize free radicals and thus participate in the prevention of cardiovascular disease and certain cancers, they act in synergy with vitamins E and C, beta-carotene and polyphenols.
Zinc is also involved in the immune system, while iron is anti-anemic.
We could sum up the main use of trace elements as follows :
- Iron against anaemia;
- Zinc in the treatment of diarrhea;
- Fluoride for caries;
- Iodine in case of thyroid deficiency or disease;
- Cobalt in the treatment of underweight.
What are the recommended intakes of the principal trace elements ?
Research on trace elements is far from complete. For some, dosing techniques and modes of action have only just been perfected and elucidated. However, in France for example, the recommended intakes are as follow :
|Iron (mg)||Zinc (mg)||Iodine (µg)||Selenium (µg)||Copper (mg)||Chromium (µg)|
|Children from 1 to 3 years old||7||6||80||20||0,8||25|
|Children from 4 to 6 years old||7||7||90||30||1||35|
|Children from 6 to 9 years old||8||9||120||40||1,2||40|
|Children from 10 to 12 years old||10||12||150||45||1,5||45|
|Adolescents 13 to 16 years old||13||13||150||50||1,5||50|
|Adolescents 13 to 16 years old||16||10||150||50||1,5||50|
|Adolescents 16 to 19 years old||13||13||150||50||1,5||50|
|Adolescents 16-19 years old||16||10||150||50||1,5||50|
What are the sources of trace elements ?
Selenium is concentrated in fish and seafood, it is also found in eggs.
Iron, zinc and copper, present in offal and meat, are particularly well assimilated. In addition, it is found in pulses and whole grains.
Manganese is abundant in vegetables and tea.
Fluoride is essential for the strength of tooth enamel and helps prevent cavities. To get your quota, it is advisable to choose drinking water that provides about 1 mg of fluoride per litre.
Iodine contributes indirectly to weight stability, as it is a constituent of thyroid hormones that regulate energy metabolism. It is provided by fish, seafood, eggs, dairy products and iodised salt.
Chromium and manganese are essential for the production or action of insulin. In the event of a deficit, there is a dysfunction of this hormone, which results in excessive fat storage. Chromium is replenished by eating eggs, liver and whole grains.
Other trace elements have been identified in the human body: molybdenum and boron, which participate in protein metabolism; lithium, important for nervous balance and silicon, which is involved in collagen synthesis.