HOT THYROIDOLOGY
(www.hotthyroidology.com), September, No 2,
2007
THE PAST, PRESENT AND FUTURE STATUS OF IODINE NUTRITION IN LATIN AMERICA.
Eduardo A Pretell, MD, MACP
ICCIDD Regional Coordinator for America, Endocrine and Metabolism Unit, High Altitute Research Institute, Cayetano Heredia Peruvian University,
Lima 27, Peru,
Geraldo Medeiros-Neto, MD, MACP
Thyroid Molecular Laboratory (LIM-25), University of Sao Paulo Medical School,
01246-900 Sao Paulo, Brazil,
Address for correspondence:
Geraldo Medeiros-Neto, MD, MACP
Thyroid Molecular Laboratory (LIM-25)
University of Sao Paulo Medical School
01246-900 Sao Paulo, Brazil
Iodine deficiency is recognized as the most common cause of preventable brain damage and mental retardation. It also causes goiter, damaged reproduction, induces neurological and mental conditions, and other disorders, all together termed Iodine Deficiency Disorders (IDD) (1). Iodine deficiency is a permanent natural phenomenon widely distributed around the world and the association of severe iodine deficiency with endemic cretinism was recognized as a geographical-epidemiological fact long ago (2,3). Pioneering studies in the Region (4,5), and elsewhere (6,7), pointed the lack of iodine during pregnancy as a major cause of irreversible brain damage in the fetus, and this, rather than goitre, emerged as the gravest consequence of iodine deficiency. At the beginning of the 1990’s it was estimated that at least 1500 million people, about one third of the world’s population, were at risk of iodine deficiency, 655 million were affected by goiter, 11 million were overt cretins, and another 43 million had some degree of mental retardation (8).
The elimination of IDD as a public health problem by the year 2000 was advocated at the UN World Summit for Children in 1990, This unprecedented Declaration was endorsed by 71 Heads of States attending the meeting and representatives from other 88 governments. The goal of the elimination of IDD by the year 2000 was adopted by the World Health Assembly in 1991 , and reafirmed by the UN General Assembly in May 2002, and by the International Conference on Nutrition in 1992. In 1993, WHO and UNICEF recommended universal salt iodization (USI) as the main strategy to achieve elimination of IDD (9). As the goal was not achieved, the UN System at the UN General Assembly Special Session for Children (UNGASS) in May 2002 set the new target for elimination of IDD the year 2005.
Although enormous progress in the sustained elimination of IDD has been made by a number of countries, according to the latest report of the WHO to the 60th World Health Assembly (May 2007), about 31% (1900.9 million) of the world's population still have insufficient iodine intakes, and, as a result, twenty-two million children each year are at risk to fail to reach their full intellectual potential. The most affected Regions are South-East Asia and Europe, while the American Region has achieved the most significant progress (10).
Recognizing the importance of IDD elimination the World Health Assembly
in 2005 adopted the Resolution WHA58.24 committing to reporting on the global
IDD situation every 3 years.
The past and present situation of IDD in Latin America
Past situation
The American countries have a rich history of iodine deficiency. Pre-Colombian statues in the Andean regions and in Mexico show that endemic goiter existed there long before Columbus arrived. In the early 20th century, iodine deficiency was recognized as a public health problem in most of the Latin America countries, The severity of iodine deficiency followed geologic patterns similar to those elsewhere in the world. The worst endemias were in isolated mountain communities. The Andean Regions and Central Mexico were the most affected, but many other parts of the hemisphere were also severely involved, and virtually no country in mainland Latin America was free of iodine deficiency (11-13).
Modern surveys for goiter within individual counties began in the 1930s. Almost all had at least some regions where the goiter prevalence was more than 50% and several countries such as Bolivia, Brazil, Ecuador, Peru, Mexico and Guatemala, had iodine deficiency in most of their territory.
In the 1950s to 1970s, most countries passed legislation on iodized salt,
establishing arbitrarily a wide range of iodization levels (11,12), likely
because of poor information on the daily physiologic needs of iodine (Table
1). Unfortunately, after some initial success in most of the countries,
later some of them relapsed, e..g.. Guatemala, Colombia and Mexico, mainly
because several common problems emerged. First, laws were not enforced and
did not fix responsibility for absorbing the cost of salt iodization. No
Latin America country addressed these issues satisfactorily. Secondly, monitoring
was either absent or inadequate. Thus, after initial enthusiasm on the part
of the government and the salt industry for regular checks on iodine levels
in salt, interest waned, monitoring lapsed, and the iodine content of randomly
selected salt samples either was absent or greatly diminished. Thirdly,
the importance of iodine deficiency and its correction was not adequately
communicated to the concerned sectors, such as different branches of the
government, the health establishment, industry, and most important, the
consumers. Hence, about thirty years later, as shown in Table
1, only a few countries were nearing iodine sufficiency, and goiter
prevalence had no significantly changed (13). In 1999, the WHO reported
that despite significant regional progress, iodine deficiency remained a
public health problem in 19 countries in the region (14). This general failure
in Latin America provides a valuable lesson related to iodine prophylaxis
elsewhere in the world.
Present situation
Most Latin American countries have reassessed their iodine status over the last 15 years and have implemented programs for the control of IDD (Table 2). Since 1985 great progresses have been made in the fight against iodine deficiency, particularly by aggressive push for iodized salt use. The achievements to date have been remarkable and indicate that the American Region will be among the first regions to attain the goal of the sustained elimination of iodine deficiency. The virtual elimination of IDD has been declared in six countries by external evaluations, Peru in 1996, Colombia in 1998, Ecuador and Venezuela in 1999, Panama in 2002, and Cuba in 2004. Bolivia was also declared to be free of IDD in 1996, but because of lack of sustainability relapsed three years later.
It must be noticed, however, that despite the great progress made by governments and agencies in the past 15 years, problems remain, such as a low level of governmental support and lack of effective monitoring of salt iodization in some countries that prevent from an effective and sustained elimination of IDD in the whole region. Some countries have regressed in the past five years, others never achieved iodine sufficiency, and still other countries have been incompletely assessed, and the risk of iodine excess has risen in more than one (Table 3).
The present article summarizes some recent information collected principally
by ICCDD in the Region (15), the countries’ reports to the Regional Meeting
Optimal Iodine Nutrition in the Americas (Lima, Peru, 2004) (16), and the
experience with the ThyroMobil project, which visited 13 countries in the
Region in 1998-2000 (17).
Iodized salt: supply, consumption and quality
As shown in Table 4 currently all the countries
in the region have reinforced their activities to reach the goal of universal
salt iodization (USI) for human consumption. The legislation concerning
the level of iodization of the salt has been corrected during the last
decade in seven countries (Brazil, Chile, Ecuador, Mexico, Panama, Paraguay,
and Venezuela) where used to be very low or very high, and in Uruguay
where the iodization of the salt was required in only half of the country.
With the exception of three countries (Haiti, Dominican Republic and Guatemala),
in all the others the production/importation volume of iodized salt is
practically covering the human potential demand, estimated on the bases
of an average annual consumption of 4-5 kilos of salt per person.
Monitoring of iodized salt is being carried out in practically all the
countries (Table 2). Although in the majority of
countries more than 80% of the salt at retail contains more than 15ppm
of iodine, the recommended figure of more than 90% has not been met or
sustained in many. It is of particular concern the situation of Guatemala
and Dominican Republic, as well the lack of information in Haiti. At least
90% of households use adequately iodized salt.
Urinary iodine and iodine nutrition
Urinary iodine excretion analysis is recognized as the most important
indicator of the impact of intervention and of the iodine nutrition. However,
regular monitoring is carried out in only a few countries (Table
2), in some the only data available is the one collected with the
ThyroMobil campaign.
As shown in Table 4, urinary iodine appears normal
in most of the countries. The median urinary iodine is above 100µg/L (i.e.,
iodine sufficient) in 16 out of the 20 (Table 2).
There are 3 countries with a median ‹100mU/L. It must be noticed
that in 11 countries the median value is above 200µg/L, and that in 5
of them (Brazil, Colombia, Honduras, Paraguay and Uruguay) their medians
are above 300µg/L, signalizing the risk of iodine excess. Recently Camargo
et al (18) reported on a higher prevalence (17.5%) of chronic autoimmune
thyroiditis in the urban area of Săo Paulo, Brazil, that was considered
to be linked to the relatively higher iodine intake (1998-2004) by the
Brazilian population (UIE median: 305 µg I/L).
Goiter prevalence
Less and less emphasis is placed on assessing the prevalence of goiter
because the palpation method is unreliable and the ultrasound method is
not available in all the countries. Recently, the ThyroMobil Project in
Latin America examined schoolchildren in 13 countries and the results
showed that prevalence was still above 5% in the majority of countries
(Table 5). This is probably due to the fact that
the goiter disappearance following iodine prophylaxis is a long lasting
process.
Contributing factors to the sustained elimination of IDD in Latin America
There have been important global and regional accounts that have significantly contributed to strengthen the development and progress of the national IDD control programs in the Region. Some of these are listed below.
PAHO/WHO Technical Group on Research in Endemic Goiter
In the early 60’s the Panamerican Health Organizations/World Health Organization gave high priority to the study of the iodine deficiency problem and founded the Technical Group on Research in Endemic Goiter, convening various prestigious Latin American scientists to promote and carry out epidemiologic as well as research studies for the prevention and treatment of IDD. The group, headed by John B Stanbury, a well recognized international authority in this field, hold five regional meetings, the first one in Venezuela (1963) and the last one in Peru (1983).
Foundation of the International Council for the Control of Iodine Deficiency Disorders (ICCIDD)
No doubt that the foundation of the ICCIDD in March 1986 has been the most important and decisive push for the countries to abandon their many decades neglected and ineffective attitude in front to the iodine deficiency problems. Moreover, the important role played by the ICCIDD in a series of Resolutions passed by the World Health Assembly and for the adoption of the goal of virtual elimination of IDD at the UN Children´s Summit in 1990, strengthen the governments commitments against IDD.
Andean Sub-Regional Program for the Control of IDD
This Program was founded by UNICEF with the collaboration of PAHO/WHO
and ICCIDD in 1991, and lasted for about ten years. The program included
originally Bolivia, Colombia, Ecuador, Peru and Venezuela, and later on
Paraguay as well. The objective of the program was to assist the country
members to reach the goal of the World Summit for Children. Its main asset
was to promote the exchanges of methodology and experiences among countries
in IEC, social marketing, salt iodization technology, epidemiology, and
monitoring. It proved effective in strengthening the IDD control programs
of individual countries.
Regional research
Many studies carried out in the Region underscore the importance and deleterious
effects of iodine deficiency on human development and the urgent need for
its elimination. The following paragraphs briefly describe some of these.
Maternal-fetal studies
Pioneering studies in the Region during pregnancy (4, 5) pointed to iodine
deficiency as a high risk situation for the pregnant woman and the fetus,
and as the major cause of impaired mental and neurofunctional development.
Concern about this finding, confirmed by others around the world (6, 7),
led the World Summit for Children to declare the elimination of IDD as
a target for the year 2000. These studies also demonstrated that this
damage can be prevented by the appropriated supplementation of iodine
during the critical periods of life.
Use of iodized oil for correcting and preventing IDD
Research studies on iodised oil for correcting and preventing iodine deficiency
paved the way for rapid control of the problem in Peru (19) and its widespread
use around the world, while awaiting the more slowly paced implementation
of USI. This method has proved to be effective and long lasting, one single
injection protects from iodine deficiency for three to five years without
complications, it is of easy application and low cost. Its administration
to pregnant women was safe and effective to protect the fetus from the
consequences of iodine deficiency. Its use has been recommended by WHO
in those areas at high risk of IDD while the iodized salt is not available
(20,21).
ThyroMobil Project in Latin America
This is the first survey assessing iodine nutrition in a whole continent
by using the same standardized methods for the estimation of the three
key variables recommended by WHO/UNICEF/ICCIDD (22), i.e. the iodine content
of salt in the community , the median urinary iodine and the prevalence
of goiter in school children. The ThyroMobil model used in this study
confirmed its specific performances in providing, on a strictly independent
basis, standardized data, communication and social mobilization, partnership
with the private sector and mobilization of national experts and authorities.
The results show remarkable success in the elimination of iodine deficiency
by iodized salt programs in Latin America. (17)
Thirteen Latin American countries (Mexico, El Salvador, Guatemala, Honduras,
Nicaragua, Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay, Peru
and Venezuela) were selected for the l project on the basis of mutual
agreement between the health authorities in each country and the Regional
Coordinator of ICCIDD. A total of 16,288 school children were examined
for thyroid volume estimated by ultrasound and spot urine samples were
randomly collected in about half of them (8,208). Salt samples were also
obtained in local markets or at local homes.
This study disclosed a wide variation in the levels of salt iodization
reflecting the different laws, which established a markedly lower or markedly
higher content of iodine in salt than the recommended range of 20 to 40
ppm. The health authorities in five countries (Brazil, Chile, Ecuador,
Paraguay and Mexico), following the report of the study have changed the
level of salt iodization.
An important role was played by the ThyroMobil system in terms of social
mobilization and awareness creation. The launching and development of
the project in each country included press conferences, lectures and distributions
of education materials, aimed to increase awareness of IDD, as well as
to reinforce commitments towards its sustained elimination among national
authorities, academicians, salt industry, and the population in general.
International reference values for thyroid volume by ultrasound
A multinational project which objectives was to develop international
reference values for thyroid gland volume by ultrasound in school-age
children from areas of long-standing iodine sufficiency. The study was
carried out in 6 sites selected from the Americas, Europe and Western
Pacific: Manama, Bahrain; Tokyo, Japan; Lima, Peru; Zurich, Switzerland;
Boston , USA; and Cape Town, South Africa. These criteria can now be used
to define goiter in the context of iodine deficiency disorders (IDD) surveillance
( 23 ).
Salt industry
The salt industry is absolutely recognized as one of the important partners
for reaching the goal of the sustained elimination of iodine deficiency.
As a matter of fact, its accelerated growing has been a key issue in the
success of the IDD control programs in the region. The expansion of its
market has been favored by the social marketing and the IEC campaigns carried
out by the national IDD programs.
Support to laboratories processing iodine
Since urinary iodine is the most important indicator of iodine nutrition,
it is important the quality assurance of laboratories processing it. The
Andean Sub- Regional Program iniciated a trial in 1998 to provide support
for quality assurance to the laboratories processing iodine in urinary and
in salt in the country’s members. Most recently, the participation of ICCIDD
in the International Resource Laboratories for Iodine (IRLI) Network has
maintained and reinforced the support to improve the quality and efficiency
of the laboratories in all the Latin American Region. Two laboratories in
the region have been selected to integrate the IRLI Network, one in Peru
– Endocrinology and Metabolism Unit, High Altitude Research Institute, Cayetano
Heredia Peruvian University (6) and the other one in Guatemala – Food Safety
and Fortification Area, INCAP.
Regional meetings
A number of scientific meetings have been organized in the Region and
important decision has been recommended.
Meetings of the PAHO/WHO Technical Group on Research in
Endemic Goiter
A series of five meetings were hold by the PAHO/WHO Technical Group on
Research in Endemic Goiter which took place in Caracas, Venezuela (1963),
Cuernavaca, Mexico (1965), Puebla, Mexico (1968), Gauruja, Brazil (1973),
and Lima, Peru (1983). These meetings were aimed to review new knowledge
on the pathophysiology of the IDD, research studies on prevention and
correction of iodine deficiency, regional epidemiology, and other important
related subjects, as well as to formulate a series of recommendations
on definitions, research, and approaches to prophylaxis.
A landmark meeting in Quito, Ecuador, in April 1994, attended by high-ranking
officials from UNICEF, PAHO/WHO, ICCIDD, and government, issued a declaration,
signed by representatives from 23 countries in the region, stating their
commitment to universal salt iodization in the Region by the year 1995
as the mid-decade goal, to be followed by the final goal of eliminating
iodine deficiency as a public health problem by the year 2000.
Salt 2000. The Latin American and the Caribbean Regional
Meeting, Bogota, Colombia 2000
In 2000 a salt regional meeting in Bogota, Colombia, reached a number
of important decisions for the salt industry: (i) encourage salt producers
to produce and distribute top quality iodized salt at a reasonable price;
(ii) pursue permanent political will for support of IDD programs; (iii)
maintain regular monitoring of quality of salt production and its effects
in human nutrition; (iiii) develop social mobilization programs to encourage
consumption of iodized salt; (iiiii) create a trust fund for implementing
regional communication programs o iodized salt consumption; (iiiiii) include
instruction on iodine deficiency and iodized salt use in the educational
system.
Regional Meeting Optimal Iodine Nutrition in the Americas,
Lima-Peru 2004
This meeting took place in Lima,Peru in May 2004, sponsored by PAHO/WHO,
UNICEF, ICCIDD and the Iodine Network. The meeting was convened to review
the current status of iodine nutrition and iodized salt in each of the
Latin American and the Caribbean countries, to identify obstacles to sustainable
optimal iodine nutrition, and to develop a strategy to overcome them.
The following key issues in achieving and sustaining optimal iodine nutrition
were discussed: (i). organization of national efforts for sustained IDD
eliminations, (ii). national coalitions to promote and sustain optimal
iodine nutrition, (iii). assuring adequately iodized salt, (iiii). effective
systems for monitoring iodine in people and in salt, (iiiii). role of
the education and communication, (iiiiii). regional cooperation-harmonization
of salt iodization levels and regulations, laboratory networks, information
sharing, (iiiiiii). current and future role of agencies and NGOs. The
meeting was attended by twenty countries (Argentina, Bolivia, Brazil,
Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador,
Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru,
Uruguay, Venezuela) were represented by their Ministers of Health or senior
leadership in health and nutrition at the Regional Meeting. Governmental
officials responsible for iodine nutrition, and representatives of the
salt industry were also participants., as well as representatives of eight
international agencies and organizations (PAHO/WHO, UNICEF, ICCIDD, Kiwanis
International, Micronutrients Initiative, Salt Institute, Network for
Sustained Elimination of Iodine Deficiency).
Conclusions and recommendations
1) Globally the countries of The Americas have made significant
progress towards the elimination of IDD; however, problems remain that
threaten the effective and sustained elimination of IDD in the whole region.
A few countries are still deficient, others have been incompletely assessed,
and the risk of iodine excess has risen in some.
2) Much of the America´s severe iodine deficiency of the past has been
corrected. At least 80% of salt at retail is adequately iodized, and only
3 countries (Guatemala, Dominic Republic, Haiti) have currently median
urinary iodine in the deficient range.
3) The achievements so far reflect effective collaboration among may partners,
both national –governments (especially Ministries of Health, Education,
and Commerce), the salt industry, the health sector, consumers, and advocacy
groups – and international – ICCIDD, UNICEF, PAHO/WHO, Kiwanis, bilateral
donors, private foundations, and others. This collaboration offers useful
models for tackling other health issues.
4) The great challenge now is sustaining the progress. The failures after
previous success in the past decades in Latin America emphasize the perils
of relaxed vigilance. The following elements are essential to sustain
progress toward optimum iodine nutrition:
√
Maintain high level political commitment to and priority on the
prevention and correction of nutritional deficiencies, such as infant
brain damage due to inadequate intakes of iodine, while at the same
time preventing the excess intake of essential nutrients. It includes
a permanent funding from regular budget, mobilization of social
demand, securing adequate resources, ownership and empowerment of
salt producers, and an enabling legal environment linked to a system
of transparent and effective enforcement.
√
Implementation of a national watch committee. Each country must
take long-range responsibility for its own program to achieve permanent
optimal iodine nutrition. A National Coalition is the critical tool
to ensure that all stake holders continue their contribution to
the progress in iodine nutrition, each according to agreed-upon
and responsibilities.
√
Monitoring of iodine in people and in salt is still non existent,
fragile, or inadequate in many countries. Monitoring of iodine in
salt and in people is essential to assess and maintain optimum iodine
nutrition status. It must be sustained and systematic, and results
must be communicated to the appropriate levels of decision to make
necessary corrections. Laboratories with adequate quality assurance
systems in place are required to guarantee the validity of monitoring
results.
√
Ensuring adequately iodized salt. Provided with adequate assistance,
all salt producers – small and large – can iodize salt effectively.
Some countries need watching for iodine excess, as a result of high
iodine ins salt.
√
Communication, including advocacy and education, needs to be planned
comprehensively as an integral part of the overall national effort.
To bridge the generation gap it is important to infiltrate and pervade
national education systems permanently.
√
Report every three years on the status of national programms and
on the efforts being made to ensure progress and sustainability
at the highest national level as well as to PAHO/WHO, in accordance
with the WHA Resolution WH58.24.
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