Nutritional Deficiencies

Iodine - updated: 16 December 2008

Adequacy of the iodine supply in The Netherlands

Eur J Clin Nutr. 1997 Nov;51 Suppl 4:S11-5

Brussaard JH, Hulshof KF, Kistemaker C, Löwik MR.

OBJECTIVE: To assess the adequacy of the iodine supply in the Netherlands and to study possible ways of increasing the iodine intake. DESIGN, SETTINGS AND SUBJECTS: Goitre and nutrition surveillance studies (intake and urinary excretion of iodine) among population groups (age: 12-85 y, n=57-1704) in the Netherlands in the period 1981-1993. Simulation studies, based on the Dutch Nutrition Food Consumption Surveys (n=6000), calculating iodine intake among population groups after fictively iodizing different food groups. RESULTS: Mean intake of iodine, measured with different food consumption methods in the period 1984-1993, met the recommended amount of 150-300 microg per day in males, but not in females. Median urinary iodine excretion levels were in the range for mild Iodine Deficiency Disorders in both sexes. According to dietary methods reflecting habitual intake and urinary iodine excretion per kg body weight or per mmol creatinin the prevalence of low iodine supply among adults is between 4 and 20% for women and between 5 and 15% for men. Iodization of different products would increase mean iodine intakes by up to 45% and would give a reduction of roughly 65% in the prevalence of low iodine intakes. CONCLUSION: The present goitre prophylaxis in the Netherlands is not optimally effective. The iodine supply is below cut-off points in 4-20% of the adult population. It is possible to decrease the prevalence of low iodine intakes without a clear risk of exceeding the maximum acceptable daily iodine intake by increasing the iodine content of baker's salt and/or by adding iodine to other foods.

Publication Types:

• Study

Calculated iodine intake before and after simulated iodization (Dutch Nutrition Surveillance System).

Ann Nutr Metab. 1995;39(2):85-94

Brussaard JH, Hulshof KF, Löwik MR.

To estimate the effect of possible goitre prophylactic measures on the intake of iodine among population groups, simulation studies, based on the first Dutch National Food Consumption Survey, were carried out. Iodine intake figures and prevalence of low intakes were calculated after fictively iodizing either bread, a combination of industrial products, milk and dairy products (without cheese) or margarine and shortenings. In addition, the effect of iodizing both bread and cheese or bread + biscuits + rusks was calculated. The simulated iodization of different products increased mean calculated iodine intakes by up to 45% and gave a reduction of 60-90% in the prevalence of iodine intakes below 100 micrograms/day. The maximum acceptable intake of 1 mg iodine per day was never reached by any subject (average of 2 days). It is concluded that it is possible to increase substantially the mean iodine intake of the Dutch population and to decrease the prevalence of low iodine intakes without a clear risk of exceeding the maximum acceptable daily oral iodine intake

Publication Types:

• Study

Iodine intake and urinary excretion among adults in the Netherlands

Eur J Clin Nutr. 1997 Nov;51 Suppl 3:S59-62

Brussaard JH, Brants HA, Hulshof KF, Kistemaker C, Löwik MR.

OBJECTIVE: To assess the prevalence of low and marginal iodine intake and urinary iodine excretion among adults in the Netherlands and to investigate determinants of urinary iodine excretion. DESIGN AND SUBJECTS: The study population consisted of 444 people aged 20-79 y, balanced for sex and 10 y age classes with an over-representation of people with a low habitual intake of vitamin B6. Food consumption was measured by three day food records and 24 h urine was sampled twice. RESULTS AND CONCLUSIONS: On average, iodine intake (mean of three days) in men was in the recommended range of 150-300 microg/d, but average intake in women was not. Mean 24 h urinary excretion values confirmed this observation. Estimation of the prevalence of low iodine excretion depended on the parameter chosen (absolute per 24 h, per kg body weight per 24 h, as concentration or per creatinin). The prevalence of low iodine supply, based on intake <100 microg/d (mean of three days) and intake or excretion parameters per creatinin excretion or per kg body weight, varied from 4-14% among adult women and from 5-17% among adult men. The prevalence of marginal iodine intake (<50 microg/d) and excretion was less than 5% in all adult age-sex groups. Urinary iodine excretion was most strongly associated with intake of iodine as such or as bread in combination with urinary excretion of sodium or potassium, confirming the importance of iodized salt (in bread) for iodine status. Age and total energy intake had a relatively minor impact on urinary iodine excretion.

Publication Types:

• Study

Iodine deficiency in Europe

Cas Lek Cesk. 1995 Jan 18;134(2):35-43

Delange F.

Iodine is a trace element present in the human body in minute amounts (15-20 mg in adults, i.e. 0.0285 x 10(-3)% of body weight). The only confirmed function of iodine is to constitute an essential substrate for the synthesis of thyroid hormones, tetraiodothyronine, thyroxine or T4 and triiodothyronine, T3 (1). In thyroxine, iodine is 60% by weight. Thyroid hormones, in turn, play a decisive role in the metabolism of all cells of the organism (2) and in the process of early growth and development of most organs, especially of the brain (3). Brain development in humans occurs from fetal life up to the third postnatal year (4). Consequently, a deficit in iodine and/or in thyroid hormones occurring during this critical period of life will result not only in the slowing down of the metabolic activities of all the cells of the organism but also in irreversible alterations in the development of the brain. The clinical consequence will be mental retardation (5). When the physiological requirements of iodine are not met in a given population, a series of functional and developmental abnormalities occur (Table 1), including thyroid function abnormalities and, when iodine deficiency is severe, endemic goiter and cretinism, endemic mental retardation, decreased fertility rate, increased perinatal death, and infant mortality. These complications, which constitute an hindrance to the development of the affected population, are grouped under the general heading of Iodine Deficiency Disorders, IDD (6). Broad geographic areas exist in which the population is affected by IDD

Publication Types:

• Review

Iodide excretion before and after revision of goiter prophylaxis (Dutch Nutrition Surveillance System).

Eur J Clin Nutr. 1992 Sep;46(9):671-8

Brug J, Löwik MR, Wedel M, Odink J.

To assess the iodine supply in The Netherlands after the revision of the goiter prophylaxis measures (Bread Act of 1982, with an increase of iodine content of bread salt) the data of a nationwide survey among Dutch elderly people conducted in 1984/1985 were analysed. Iodide excretion in 24 h urine samples was used as the main iodine status indicator. The data were compared with data on iodine nutriture obtained among an elderly population in The Netherlands before the revision of goiter prophylaxis. High prevalences (greater than or equal to 37%) of low iodine excretion (less than 0.78 mumol/24 h; 100 micrograms/24 h) were found for Dutch elderly people. Mean urinary iodide excretion was 0.95 mumol/24 h (121 micrograms/24 h) for men and 0.79 mumol/24 h (100 micrograms/24 h) for women which is low, especially among women, in comparison with the United States recommended dietary allowance (118 mumol/day = 150 micrograms/day). Consistent positive associations of iodide excretion were found with urinary potassium and sodium excretion, bread consumption and total iodine intake. Bread, as the iodine carrier chosen for goiter prophylaxis in The Netherlands, was found to be the main dietary iodine source. No improvement in iodine nutrition was found among the elderly studied in 1984/1985 in comparison with an elderly population seen in 1981. Therefore, it is concluded that the present measures regarding goiter prophylaxis in The Netherlands might be of limited effectiveness.

Publication Types:

• Dutch Nutrition Surveillance System

Publication Types:

• Review