Minerals Part IV: Iron and iodine
Some people will be familiar with the terms iodine and iron within the spectrum of minerals and trace elements. The reason for the popularity of these elements lies on the one hand in their importance for routine medical diagnostics, such as checking thyroid levels and ruling out iron deficiency anaemia, and on the other hand in the well-known iodisation of our common table salt.
But iodine and iron are more than just famous elements, because they are considered immensely important players in our biochemical cycle. In the following, we would like to specifically explain the dose, function and undersupply of the individual elements.
The facts at a glance:
- Iron is the most abundant trace element in the body. Depending on age and sex, 10 to 15 milligrams should be consumed daily. Pregnant women and breastfeeding mothers may take more.
- Meat such as poultry and offal are particularly suitable sources of iron. When it comes to iron absorption in the intestine, it is important to bear in mind that other food components can interfere with or promote absorption.
- For a sufficient amount of iodine, 180 to 200 micrograms daily are recommended. Pregnant and breastfeeding women, however, have to resort to higher values. Iodised table salt, seafood and dairy products are particularly good sources.
- Iron is responsible for oxygen transport, electron transfer and functions as a coenzyme of various enzymes. An iron deficiency leads to a disturbed functioning of certain enzymes as well as to a reduced supply of oxygen. An iron overdose can also damage specific tissues and contribute to diseases such as diabetes.
- Iodine is needed for thyroid hormone synthesis. These hormones play an important role in differentiation processes, growth and metabolic pathways. Iodine deficiency affects insufficient thyroid hormone synthesis. An overdose of iodine is rare, but can lead to increased thyroid hormone synthesis and various symptoms
Iron is the most common trace element in our body.
Our own body has about 50 milligrams of iron per kilogram of body weight. Iron is found in various places in our system. In particular, iron is found in haemoglobin. This substance is an essential component of our red blood cells (= erythrocytes) and, together with iron, is responsible for transporting oxygen. In addition, the body has, among other things, storage iron and transport iron as sources of iron.
Sufficient iron intake: meat and offal are particularly suitable.
To avoid an undersupply of iron, 10–15 milligrams per day should be consumed, depending on age and sex, according to the German Society for Nutrition. Pregnant and breastfeeding women are recommended to substitute 20 or 30 milligrams daily. Due to the rather low, but nevertheless necessary daily dose, iron is one of the elements that is only needed in traces. Significant sources include in particular meat such as poultry and offal. If necessary, vegetables, pulses, cereals and nuts can also be used.
Pay attention to other food components in iron absorption
In the context of iron absorption in the intestine, however, it must be remembered that the absorption of various other food components can be promoted or inhibited. For example, animal proteins, fructose or vitamin C promote iron absorption. Inhibition, on the other hand, is caused by selected dietary fibres or calcium.
The trace element iodine as a building material for thyroid hormones
According to the German Nutrition Society, only 180 to 200 micrograms of this element are needed daily for adequate iodine levels (depending on age and sex). Again, values between 230 and 260 micrograms are recommended for pregnant and breastfeeding women. With regard to the substitution dimension, iodine is therefore classified with the trace elements. The most favourable sources are iodised table salt, seafood or dairy products. Since the soils and drinking water throughout Germany do not contain enough iodine, this important element is added to our salt. Despite the small amount our body needs, iodine is of immense importance for every individual. If there is a deficiency, this affects our thyroid hormones in particular, which are involved in numerous processes throughout the body’s system.
Iron functions primarily as an oxygen transporter
When considering the functions of iron, three core areas stand out, one of which is particularly prominent — oxygen transport. In addition to this outstanding function, iron also contributes to the proper functioning of cells as an electron transporter. By acting as a coenzyme, it also supports the proper functioning of various enzymes.
Stressful consequences of an iron deficiency/iron surplus
In the context of an iron deficiency, the enzymes that make use of the electron transfer property of iron suffer in particular, as does the transport of oxygen in the body. In particular, an undersupply of oxygen to the body causes fatigue and reduced performance. The cause of such deficiencies is often an insufficient iron intake.
On the other hand, an overdose of iron is considered to be at least as harmful. Increased storage in certain tissues can cause damage. The liver in particular can be attacked to such an extent that cirrhosis of the liver is imminent. But the heart and pancreas are also often affected by excessive storage. It is not uncommon for this to lead to cardiomyopathies and diabetes.
The only known function of iodine: participation in the synthesis of thyroid hormones.
Iodine has one significant function above all: the synthesis of the thyroid hormones T3 and T4. These hormones are of outstanding importance for growth and differentiation of the organism, especially during development. Taken together, T3 and T4 are involved in a multitude of metabolic processes. A deficiency of these hormones, especially from birth, can lead to reduced intelligence and short stature. Iodine deficiency is not infrequently the cause of hypothyroidism (= too little thyroid hormone).
Another main feature of iodine deficiency is the so-called goitre. This is an enlargement of the thyroid gland. Depending on the size of the goitre, it can lead to a wide variety of complications.
Iodine overdose is difficult to achieve
Although a daily intake of more than 500 micrograms of iodine can cause damage, a high consumption of iodine is extremely rare. However, if such a constellation were to occur, hyperthyroidism (= too much thyroid hormone) would result. Symptoms would include weight loss, high pulse, fever or muscle weakness.
Text sources:
(1) https://www.dge.de/wissenschaft/referenzwerte/jod/
(2) https://www.dge.de/wissenschaft/referenzwerte/eisen/
(3) Stalla, Endocrinology and Metabolic Diseases, 2007
(4) Biesalski, Pocket Atlas of Nutrition, 7th edition, 2017
(5) Silbernagel et al, Physiology, 8th edition, 2018.
(6) Horn, Biochemistry, 8th edition, 2020.
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