Iodine deficiency
Iodine deficiency (also iodine deficiency ) occurs in humans when the body takes in too little iodine through food or drinking water without further supply of trace elements . Iodine is needed almost exclusively to build up thyroid hormones . With a good supply, the thyroid can store ten milligrams of iodine; this corresponds to the iodine requirement for three months.
Recommended daily intake of iodine
| Age group | Germany, Austria |
Switzerland, WHO |
|---|---|---|
| baby | ||
| 0 to less than 4 months a | 40 | 50 |
| 4 to less than 12 months | 80 | 50 |
| children | ||
| 1 to under 4 years | 100 | 90 |
| 4 to under 7 years | 120 | 90 |
| 7 to under 10 years | 140 | 120 |
| 10 to under 13 years | 180 | 120 |
| 13 to under 15 years | 200 | 150 |
| Teenagers and adults | ||
| 15 to under 19 years | 200 | 150 |
| 19 to under 25 years | 200 | 150 |
| 25 to under 51 years | 200 | 150 |
| 51 to under 65 years | 180 | 150 |
| 65 years and older | 180 | 150 |
| Pregnant women | 230 | 200 |
| Breastfeeding | 260 | 200 |
| a estimate | ||
The German Nutrition Society (DGE) recommends a daily intake of 180–200 µg iodine per day for adults (slightly more for pregnant and breastfeeding women) and 40–200 µg for children and adolescents. The actual iodine intake in Germany was estimated by the DGE 2003 to be 110–120 µg iodine per day in adults.
Causes and epidemic situation of iodine deficiency
In Central Europe, the agriculturally used soils are comparatively poor in iodine compounds. This applies not only to the Alpine region, but also to the soils of the coastal plains in Denmark and the Netherlands . The reason why the soils of the humid climatic zones are so poor in iodine is that iodine was washed out in the course of the earth's history. The iodine content in the secondary environmental compartments of water and arable land is subject to many influencing factors. Mountainous regions remote from the sea are more likely to be affected by iodine deficiency than the lowlands. In Europe, these were traditionally the Alpine countries and the Balkans. In North America it was especially the areas around the great lakes .
The WHO estimates that around 750 million to one billion people worldwide are affected by iodine deficiency. In Western and Central Europe, this affects more than 380 million people.
The thyroid gland can absorb and accumulate around 40 percent of the iodine it consumes from the blood . The rest is excreted through the kidneys . The amount of iodine that is excreted daily in the urine is a good measure of the organism's iodine supply. The measured value of the daily iodine excretion is based on creatinine , a metabolic product that is also excreted in the urine; so you can get an age-independent parameter. According to the DGE recommendation, the target value is 150 µg / g creatinine. The World Health Organization (WHO) classifies iodine deficiency and oversupply as follows
| Hazard potential | Urinary excretion of iodine in µg / l |
|---|---|
| negative effects on health | over 300 |
| Risk of iodine-induced hyperthyroidism in vulnerable groups | 200-299 |
| Degree of iodine deficiency | with iodine excretion |
|---|---|
| No shortage | over 150 µg iodine |
| 0 (WHO) | 100–150 µg iodine |
| I (WHO) | 50–100 µg iodine |
| II (WHO) | 25–50 µg iodine |
| III (WHO) | less than 25 µg iodine |
Symptoms and consequences of iodine deficiency
Iodine is an essential trace element and especially important for the functioning of the thyroid gland . The thyroid gland synthesizes the vital iodine-containing hormones thyroxine (tetraiodothyronine, T 4 ) and triiodothyronine (T 3 ). Chronic iodine deficiency initially leads to hyperplasia and later hypertrophy , i. H. to increase the size of the thyroid gland. This is clinically noticeable as a goiter (medical: goiter ). The endemic goiter was in earlier centuries the characteristic of entire populations, e.g. B. in Bavaria, Switzerland or Austria. If the iodine deficiency persists for a long time, nodular goiter with autonomous adenomas can develop. If the iodine deficiency situation is suddenly corrected (e.g. by increasing the intake with the diet or by giving X - ray contrast media with a high content of iodine ), hyperthyroidism (overactive thyroid gland) can develop due to excessive hormone production by the autonomic areas .
The hormones T 3 and T 4 are crucial for early childhood brain development. A pronounced deficiency of these hormones at birth leads to more or less severe mental retardation (up to cretinism ). That is why every newborn is routinely checked for hypothyroidism (underactive thyroid function) in order to treat it as soon as possible. If the treatment is delayed by only a few weeks, this can result in a mental handicap that makes it impossible to go to higher education later. The most common cause of hypothyroidism in the newborn is insufficient iodine intake during pregnancy. Sufficient iodine intake is therefore of particular importance during pregnancy. A meta-analysis from ten different studies showed that chronic iodine deficiency led to a mean reduction in intelligence quotient of 13.5 points. Studies from all parts of the world have shown that chronic iodine deficiency leads to mental retardation in children. Iodine deficiency is considered to be the world's largest single cause of preventable brain damage and intellectual disability.
Mental retardation due to iodine deficiency was an endemic phenomenon in iodine deficient areas in earlier times. In 1748, during a trip through Styria , the Scottish philosopher David Hume described his impressions in shock: “As appealing as the country is in its roughness, the inhabitants are wild, disfigured and monstrous in their appearance. Very many of them have ugly swollen necks. Cretins and the deaf and dumb frolic in every village. The general sight of the people is the most shocking I've ever seen. "
Medical history
In ancient China , doctors recommended eating seaweed and sponges . Pure iodide has been available since the 19th century . From 1918 onwards, the Swiss doctor Otto Bayard introduced iodized salt into the communities in his practice area in the Nikolaital, using the right amount of iodine in the table salt, and showed that development disorders, the enlargement of the thyroid gland, goiter and nodule formation were not undesirable and have damage treated successfully. Building on this, the Swiss Goiter Commission, founded by the Federal Office of Public Health in 1922, recommended the use of iodine-containing table salt to the population and the twenty-five cantonal authorities, and based on these empirical studies it determined the amount of calcium iodine added to table salt. The introduction of structured iodine prophylaxis according to Bayard throughout Switzerland in the following years had a worldwide pioneering character.
There is statutory iodine prophylaxis in Switzerland , Austria , the USA , Taiwan and until reunification in the GDR . In the unified Germany, however, there is no statutory iodine prophylaxis.
prevention
A sufficient iodine supply of 150 to 200 micrograms per day is possible in deficient areas like Germany through the careful consumption of foods containing iodine such as sea fish as well as food supplements such as seaweed preparations and / or by taking iodine tablets. In Europe, sea fish is generally the most widely available food with the highest iodine content ( haddock approx. 240 µg in 100 g or herring approx. 50 µg in 100 g).
If seaweed is consumed frequently, attention should be paid to the iodine content of the algae, otherwise the maximum amount of 500 µg per day provided by the WHO is easily exceeded. This maximum amount is an average. Exceeding this on individual days is not a problem if less consumption is consumed on other days. The Stiftung Warentest states that algae can contain 5 to 11,000 µg of iodine and recommends only consuming products whose iodine content is known. It is often stated on the packaging.
The usual household amount of iodized table salt increases the iodine supply of the consumers by approx. 20 µg daily, in addition there is the iodine in ready-made foods and meat products, which fluctuates strongly. On the one hand, iodized salt in Germany contains 20 µg of iodine per gram of salt in the form of potassium iodate ; In 2014, the concentration in Switzerland was increased from 20 to 25 µg iodine per gram of salt. On the other hand, iodide is added on a voluntary basis to increase the iodine supply in meat products, dairy products, bread, ready meals, canteen meals and common table salt . The proportion of iodized salt in commercial food is around 70% in Switzerland and around 30% in Germany. After all, animal feed is iodized in several countries, including Germany. The EU sets limit values.
In areas where salt iodination is not possible, an oil capsule enriched with iodine can be added every one or two years. This is mostly the case in developing countries when the salt supply is decentralized or salt production is private.
Situation in Germany
Numerous epidemiological studies over the last few decades confirm the natural iodine deficiency in Germany . The largest study (approx. 6000 people) was carried out by Hampel et al. Surveyed 1993–1994 and presented in 1995. The mean urinary iodine excretion was 72 µg iodine per gram creatinine. Only nine percent of the test persons were adequately supplied with more than 150 µg / g of iodine. 17% had an iodine deficiency of grade 0 (WHO), 25% grade I, 17% grade II and 2% grade III. Inhabitants of the coastal regions had no higher iodine excretion than the inhabitants of the low mountain ranges and the foothills of the Alps.
The shortage situation led to 100,000 thyroid operations per year in Germany at the end of the 1990s. Iodized salt had been available since 1959, but was initially only approved for medical treatment until 1981. It was not included in the Additive Admissions Ordinance until 1989 and the declaration obligations for producers were reduced in the following years.
As a result of the public relations work of the Federal Center for Health Education and the industry- financed working group iodine deficiency and the increasing use of iodine-enriched table salt in households (83%), in large kitchens and in the food industry (29%), the iodine excretion has increased significantly since then, especially according to recent studies with children. Comprehensive data are not yet available, but the voluntary nature of these measures means that high regional and individual fluctuations are to be expected. Even the latest studies still show a high proportion of underserved people. The measurements by Hampel et al. In 2001, 3000 school children from 128 cities in Germany showed an average iodine excretion of 148 µg / g, but 27% still had an iodine deficiency grade I or worse. A WHO report in 2003 classified Germany as optimally cared for (except for pregnant and breastfeeding women). According to the guidelines of the WHO, nationwide data on iodine supply should be collected every five years. This took place in Germany in 1996 and 2006.
Results from the child and youth health survey of the Robert Koch Institute are available for the current epidemic situation of iodine supply in children and adolescents : median ioduria of 117 µg / l. The pharmacoepidemiological situation of the use of thyroid preparations in adults and of serum levels of the thyroid hormones triiodothyronine , thyroxine and TSH is presented in a GBE publication from the population-representative data of the RKI health surveys (see web link: Report of the Robert Koch Institute).
In a study from 2005 (published in 2009), 64% of the people examined showed sufficient iodine excretion, but 23% a mild, 10% a moderate and 3% a severe iodine deficiency. The authors saw the reasons for the improved iodine supply primarily in the higher iodine content of milk and dairy products and the widespread use of iodized table salt in restaurants. The food industry does not yet use iodized table salt sufficiently often.
Problems
Data from countries with legally mandatory salt iodine, such as Austria, showed that during the first few years after the introduction of higher iodine levels, autoimmune diseases of the thyroid gland ( e.g. Graves' disease ) can be aggravated. An optimal prophylaxis should therefore be based on needs, i. H. while avoiding an oversupply, and carefully monitored epidemiologically. Patients with such diseases should be identified and treated early on.
In order to prevent damage to health, the European Food Safety Authority has recommended restricting the permitted iodination of animal feed, i.e. ultimately also that of human beings. As a result, the upper limits for the iodination of animal feed for chickens and cows were halved by EU Regulation No. 1459/2005. The EU has tried to take into account the total iodine intake of humans at the end of the food chain. However, when the current limit value is fully exhausted (5 mg / kg) and only concentrated feed is used, doses of 400–1200 µg / l are still possible in cow's milk, which corresponds to a multiple of the recommended daily dose if one liter of cow's milk is consumed daily. In Germany the iodine content of concentrated feed is only 1 mg / kg with an average of 50% concentrated feed (resulting in an average milk iodine content of 100 µg / l).
The Stiftung Warentest also determined the milk iodine content in a large milk test. It was between 30 and 180 µg / l, organic milk types were in the lower third of this range. The World Health Organization (WHO) warns of negative health consequences with a median value of over 300 μg iodine / l urine.
Web links
- Iodine supply in Germany is on the decline again - Tips for a good iodine supply - Questions and answers from the Federal Institute for Risk Assessment (BfR) updated in February 2020
- Working group iodine deficiency
- Iodine Status Worldwide. WHO 2004 (PDF; 1.24 MB;) English
- On the enrichment of iodine in foods of animal origin, Nutrition Review 2006. (PDF; 82 kB)
- Position of the Federal Institute for Risk Assessment on iodine prophylaxis, March 31, 2012
- Position of the German. Ges. For Nutrition, 2003
- Report of the Robert Koch Institute on thyroid diseases in Germany. (PDF) Status 2002
- Report by the Federal Institute for Consumer Health Protection and Veterinary Medicine (BgVV), today the Federal Institute for Risk Assessment (BfR): Germany is still an iodine deficiency area . (PDF) Status 1997
Individual evidence
- ↑ Iodine: Recommended intake. German Nutrition Society, accessed on February 19, 2018 .
- ↑ DGE -Info: With iodized salt and a balanced diet consistently, effectively and safely against iodine deficiency. Research, Clinic and Practice 11/2003 full text
- ^ Mortality and Burden of Disease Estimates for WHO Member States in 2002 . (xls; 3.0 MB) In: World Health Organization. 2002, accessed January 4, 2011 .
- ↑ European FOREGS Atlas , 2005, Forum of the European Geological Surveys Directors, weppi.gtk.fi (PDF) Map (PDF)
- ^ R. Fuge: Geochemistry of iodine in relation to iodine deficiency diseases . Geological Society, London, Special Publications 1996 (113), pp. 201-211
- ^ Iodine status worldwide: WHO Global Database on Iodine Deficiency. In: Bruno de Benoist u. a. (Ed.): Department of Nutrition for Health and Development . World Health Organization, Geneva 2004, ISBN 92-4-159200-1 , who.int (PDF; 1.3 MB)
- ↑ a b WHO 2004 Iodine Status Worldwide, p. 31, gtk.fi ( Memento from September 27, 2007 in the Internet Archive ) (PDF) whqlibdoc.who.int (PDF; 1.3 MB)
- ↑ The Cretinnen in Tyrol, Salzburg, Steyermark, Carinthia, Ungern, Galicia and Bohemia . In: Franz Sartori (Hrsg.): Oesterreichs Tibur, or nature and art paintings from the Austrian Empire . Anton Doll, Vienna 1819, p. 211 .
- ↑ N. Bleichrodt, MP Born: A meta-analysis of research on iodine and its relationship to cognitive development. In: JB Stanbury (Ed.): The damaged brain of iodine deficiency. New York, Cognizant Communication, 1994, ISBN 1-882345-03-7 , pp. 195-200.
- ↑ Alicia Pineda-Lucatero, Laura Avila-Jiménez, Rosa Isela Ramos-Hernández, Clementina Magos, Homero Martínez: Iodine deficiency and its association with intelligence quotient in schoolchildren from Colima, Mexico . In: Public Health Nutrition . tape 11 , no. 07 , 2008, p. 690-698 , doi : 10.1017 / S1368980007001243 , PMID 18205986 .
- Jump up ↑ M. Qian, D. Wang, WE Watkins, V. Gebski, YQ Yan, M. Li, ZP Chen: The effects of iodine on intelligence in children: a meta-analysis of studies conducted in China. In: Asia Pac J Clin Nutr. 2005; 14 (1), pp. 32-42. PMID 15734706
- ^ Piedad Santiago-Fernandez u. a .: Intelligence Quotient and Iodine Intake: A Cross-Sectional Study in Children . In: The Journal of Clinical Endocrinology & Metabolism . tape 89 , no. 8 , August 2004, p. 3851-3857 , doi : 10.1210 / jc.2003-031652 .
- ^ Sarah C Bath, Colin D Steer, Jean Golding, Pauline Emmett, Margaret P Rayman: Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC). In: The Lancet . 2013, pp. 331-337, doi: 10.1016 / S0140-6736 (13) 60436-5 .
- ^ F. Delange: Iodine deficiency as a cause of brain damage . In: Postgraduate Medical Journal . tape 77 , no. 906 , January 4, 2001, p. 217-220 , doi : 10.1136 / pmj.77.906.217 , PMID 11264481 .
- ^ Ernest Campbell Mossner: The Life of David Hume . 2nd Edition. Clarendon Press, Oxford 1980, ISBN 0-19-924336-0 , pp. 338 (English): … as much as the Country is agreeable in its Wildness; as much are the Inhabitants savage & deform'd & monstrous in their appearance. Very many of them have ugly swelld Throats: Idiots, & Deaf People swarm in every Village; & the general aspect of the people is the most shocking I ever saw.
- ↑ Often too much iodine in seaweed products , In: Geschäftszentrale.de, as of September 2, 2019
- ↑ The Federal Council: Iodine content in table salt is increased. Retrieved January 29, 2018 .
- ↑ M. Thamm, U. Ellert, W. Thierfelder, K.-P. Liesenkötter, H. Völzke: Iodine Supply in Germany - Results of the iodine monitoring in the Child and Adolescent Health Survey (KiGGS) (PDF; 572 kB)
- ↑ R. Hampel, G. Bennöhr, A. Gordalla, H. Below: Jodidurie in adults in Germany 2005 in the WHO target area. In: Medical Clinic. Volume 104, Number 6, pp. 425-428, June 2009 doi: 10.1007 / s00063-009-1090-y
- ↑ steiermark.orf.at
- ^ Benedikt L. Baltisberger, Christoph E. Minder, Hans Bürgi: Decrease of incidence of toxic nodular goitre in a region of Switzerland after full correction of mild iodine deficiency . In: European Journal of Endocrinology . tape 132 , no. 5 , January 5, 1995, pp. 546-549 , doi : 10.1530 / eje.0.1320546 , PMID 7749493 .
- ↑ efsa.europa.eu
- ↑ idw-online.de
- ↑ G. Flachowsky et al. a .: For iodine enrichment in foods of animal origin. (PDF; 82 kB) In: Nutrition review. 53 (200), p. 17 ff.
- ↑ Milk test by Stiftung Warentest , issue 11/2007.
