Micronutrients in women during pregnancy: Focus on iodine and folic acid
Main advantage of iodine supplement during pregnancy and preconception:
Helps development of brain both during fetal and early postnatal life.
Prevents birth of children with learning disabilities.
Main advantage of folic acid supplementation during preconception and pregnancy:-
Significantly reduces the occurrence of neural tube defects.
INTRODUCTION
Micronutrients play a key role in daily metabolic activities and maintenance of tissue
Function in men and women alike.
In women the role of micronutrients during childbearing years, pregnancy and lactation is well established.
The micronutrients status of the women has an effect not only on their health, but also has an impact on the next generation.
THE MICRONUTRIENTS STATUS OF THE WOMEN HAS AN EFFECT NOT ONLY ON THEIR HEALTH, BUT ALSO HAS AN IMPACT ON THE NEXT GENERATION.
IN addition to this, micronutrients also have substantial impact on women’s health
During their adolescence and the aging years.
Single micronutrient deficiency states in women can easily recognized and treated.
However, deficiency of multiple micronutrients requires special concern as multiple micronutrients deficiencies in women are common and most complicated to analyze in the individual woman has been well such as iron, calcium, iodine, folic acid and vitamin-A and vitamin
Consequently, efforts are needed to improve diet and quality to ensure proper supply of micronutrients in all stages of the women’s life , with more emphasis being given to the pre-conception and pregnancy periods.
The current research explores the role of micronutrients like iodine and folic acid in women during pregnancy and pre-conception
IODINE AS MICRONUTRIENT:-
Iodine is essential component of the hormones produced by thyroid gland.
Thyroid hormones, and therefore iodine, are essential for mammalian life.
The native iodine content of most foods and beverages is low.
In general, commonly consumed foods provide 3-80 microgram per serving.
Iodine is ingested in several chemical forms and is rapidly and nearly completely absorbed in stomach and duodenum.
Iodate, widely used in salt iodization, is reduced in the gut and absorbed as iodide.
Iodine deficiency has multiple adverse effects in humans, termed Iodine Deficiency Disorders (IDD), due to inadequate thyroid hormones production.
Globally, it is estimated that 2 billion individuals have an insufficient intake , and south asian and south-saharan African population are particularly affected.
India too suffers from grave burden of Iodine Deficiency Disorders (IDD).
In India, no state is free from iodine deficiency and more than 200 million people are on the risk of Iodine Deficiency Disorders (IDD).
Result of the recent survey conducted in 325 districts covering all the states/union territories have revealed that 263 districts are endemic where the prevalence of Iodine Deficiency Disorder (IDD) is more than 10%.
Iodine is necessary for normal growth and neurodevelopment of fetus during pregnancy.
Iodine deficiency during this critical period could result in brain damage to the fetus.
According to WHO recommendation/ guidelines, women of reproductive age (15-49 yrs)
Require a daily of 150 microgram of iodine as a supplement.
The WHO recommends 250 microgram of iodine during pregnancy and lactation periodwhich is nearly double the normal requirement.”
This necessitates external supplementation of iodine in pregnant and lactating women in addition to the routine supplementation of iodine obtained through foods rich in iodine and iodized salt.
Globally, it is estimated that 2 billion individuals have an insufficient iodine intake,
And South Asia and sub-Saharan African Populations are particularly affected.
In India, no state is free from iodine deficiency and more than 200 million people are ‘at risk’ of IDD. Iodine is necessary for normal growth and neurodevelopment of the fetus during pregnancy. Iodine deficiency during critical period could result in brain damage to the fetus.
INCREASED REQUIREMENT OF IODINE IN PREGNANCY:-
Iodine is essential component of the hormones produced by thyroid gland.
Thyroid hormones, and therefore iodine, are essential for mammalian life.
The native iodine content of most foods and beverages is low.
In general, commonly consumed foods provide 3-80 microgram per serving.
Iodine is ingested in several chemical forms and is rapidly and nearly completely absorbed in stomach and duodenum.
Iodate, widely used in salt iodization, is reduced in the gut and absorbed as iodide.
Iodine deficiency has multiple adverse effects in humans, termed Iodine Deficiency Disorders (IDD), due to inadequate thyroid hormones production.
Globally, it is estimated that 2 billion individuals have an insufficient intake , and south asian and south-saharan African population are particularly affected.
Pregnancy is associated with the profound changes in thyroid functioning and the requirements for iodine.
The influence of a rise in concentration of oestrogen results in marked increase in the concentration of serum thyroxine binding globulin which begins during early gestation, reaches a plateau at mid-gestation and is maintained thereafter.
In the early gestation period there is an increase in renal blood flow and glomerular filtration, which leads to an increased iodide clearance from the plasma and thus to an obligatory loss of iodine.
Nearing the end of the first trimester, there is direct stimulation of thyroid gland by an increase in the concentration of gonadotropin (HCG) that may lead temporarily to a slightly higher increased concentration of free thyroxine.
Finally, significant changes occur in the peripheral metabolism of maternal thyroid hormones during the second half of gestation, mainly under the influence of placental type 3 iodthyronine deiodinase.
All these events represent profound metabolic changes associated with the first half of gestation that constitutes a transition from a preconception steady thyroid gland.
This requires an increase in hormone production by the maternal thyroid gland of about 50%.
MICRONUTRIENTS AND EFFECT OF THEIR DEFICIENCIES:-
MICRONUTRIENTS include at least 14 trace elements and 13 vitamins which are required by humans in very small amounts.
The trace elements include Arsenic (As), Boron (B), Chromium (Cr), Copper (Cu), Flourine (F), Iodine (I), Iron (fe), Manganese (Mn), Molybdenum (Mo), Nickel (Ni),
Selinium (Se), Silicon (Si), Vanadium (V), and Zinc (Zn).
The vitamins B6, B12, A , C, D ,E and vitamin-K.
While the trace elements are involved in modulating enzyme activity, the vitamin play an important role or plays an active part within complexes biochemical reactions in the body.
The primary cause of micronutrients can be attributed to overall low dietary intake.
In the addition, genetic factors, nutrients interactions,a poor absorption, drugs and diseases may contribute to micronutrient deficiency especially at an individual level.
The inadequate intakes of calcium, iron , folate, vitamin D, and zinc deficiencies can be addressed to inadequate consumption of fruits, vegetables, meat, and animal source of food.
Iron inadequacy is a major contributor to suboptimal outcomes of women throughout the life cycle.
Inadequacy during pregnancy and lactation can impact the ability to provide optimal feeding after delivery.
Deficient folate intakes can result in neural tube and other birth defects that can occur early in pregnancy.
Severe iodine inadequacy can lead to goiter, hypothyroidism, and cretinism. Iodine deficiency results in a global loss 10-15 IQ points at a population levels and continues the world’s greatest single cause of preventable brain damage and mental retardation
Vitamin-A inadequacy can cause night/complete blindness and can cause or can result in higher susceptibility to morbidity and mortality from infectious diseases and adverse reproductive outcomes.
Zinc is a cofactor for over 100 coenzymes and selenium is required in the form of selenocytesteine within the enzyme glautathione peroxidase .
Riboflavin and niacin play an active role in the electron transfer system or electron transport chain and folic acid in methyl group transfer.
All these micronutrients and vitamins to provide energy , proteins and nucleic acids.
Deficiencies of these individual micronutrients can be easily identified, but the milder forms of deficiency, often of multiple micronutrients are much more common and more difficult to recognize.
A series of stages with biochemical or physiological consequences can result as a person progressively develops more severe depletion of one or more micronutrients.
Specific and localized tissue deficiencies can occur and lead to pathological changes.
Such situation can be defined as subclinical deficiency varies for each micronutrient, and depends upon the nature and amount of body stores.
Need of nutrient intake during pregnancy:-
Intake of nutrition is important to the well-being of pregnant women and the fetus.
Inadequate nutrient intake can lead to maternal anemia, increasing the risk for older maternal morbidities And mortality, fetal growth retardation and low fetal birth weight .
Inadequate of both macronutrients and micronutrients intake in pregnant women has been reported in both developing countries and in developed countries.
Consequently, maternal nutritional status, with respect to both macro and micro nutrients is known to be important determinant of perinatal and neonatal survival and wellbeing of the pregnant women.
Inadequate nutrient intake can lead to maternal anemia, increasing the risk for other maternal morbidities and mortality, fetal growth retardation
and low fetal birth weight\.
The iodine requirement during pregnancy is increased due to:_
1) An increase in maternal T4 production to maintain maternal euthyroidsm and transfer thyroid hormone to the fetus early in the first trimester, before the fetal thyroid is functioning.
2) Iodine transfer to the fetus , particularly in later gestation and
3) An increase in renal iodine clearance.
In order to sustain an increased production of thyroid hormones, it becomes necessary to draw iodine from already depleted thyroid stores.
This is the rationale for the excessive stimulation of thyroid gland observed during a pregnancy that takes place in iodine deficient conditions (figure d).
The consequence of this are relative hypothyroxinaemia, preferential secretion of tri-iodothyronine , an increased concentration of serum thyroid – stimulating hormone as well as serum thyroglobulin and, finally, increase in thyroid volume leading to goiter.
Iodine deficiency and hypothyroidism during pregnancy have long been known to be associated with neurological deficits and mental retardation.
There is also evidence for an increased risk of adverse effects on obstetrical outcomes such as pre-eclampsia or placental abruption, and negative effects on the off spring such as preterm birth fetal death, or low birth weight due to iodine deficiency.
Role of iodine in early brain development
Iodine is required for synthesis of thyroid hormones which are crucial for the development of the brain both during fetel and early postnatal life.
If iodine deficiency is severe, it may induce maternal and fetal hypothyroxinaemia from early gestation onwards.
It is clearly that maternal hypothyroxinemia (defined as thyroxine (T4) concentrations) is potentially damaging for neurodevelopment of the fetus throughout pregnancy and especially before midgestation as then the only source of T4 for developing brain.
Despite a highly efficient uterine-placental ‘barrier’ to their transfer, very small amounts of T4 and triiodothyronine (T3) of maternal origin are present in fetal compartment by 4 weeks after conception, with T4 increasing steadily thereafter.
A major proportion of T4 in fetal fluids is not protein-bound and the ‘free’ T4 (FT4) available to fetal tissues is determined by the maternal serum T4.
Despite very low T3 and Free t3 (FT3) in fetal fluids, the t3 generated locally from t4 in cerebral cortex reaches adult concentration by midgestation, and is partially bound to its nuclear receptor.
As a result, women unable to increase their production of T4 early in pregnancy would constitute a population would constitute a population at risk for neurological disabilities in their children
Women unable to increase their population of T4 early in pregnancy would constitute a population at risk for neurological disabilities in their children.
Consequently , consumption of iodine supplements at the onset of pregnancy ( or earlier)
Can prevent birth of many children with learning disabilities
Published data also indicate that iodine deficiency may have negative effects on the
Clinical studies indicate that moderate iodine deficiency is associated with a 4.26 times higher risk of low IQ and risk of having an IQ below 70 was greater in children with urinary iodine levels less than 100microgram/litre.
According to sources released by ministry of women and child development in India, the number of children are born mentally impaired due to IDD is highest in India.
Every year over 13 million infants are born unprotected from IDD.
About 6.6 million children are born mentally impaired every year in India due to iodine deficiency and intellectual capacity is reduced by 15% across India .
Consequently, consumption of iodine supplement at onset of pregnancy( for earlier) can prevent birth of many children with learning disabilities.
Every year 13 million infants are born unprotected from IDD. About 6.6 million children are born mentally impaired every year in India due to iodine deficiency and intellectual capacity is reduced by 15% across India due to iodine deficiency
Folic acid as a micronutrient:-
Folic acid also known generally as folate or folacin, is a member of b-complex family of vitamins.
The best folate sources in foods are green leafy vegetables , sprouts etc, kidney also contains high amount of folate.
Folic acid function primary as a methyl-group donar involved in many important body processes, including DNA synthesis.
Folic acid is instrumental in reducing homocysteine levels and occurance of neural tube defects(NTD)
NEED OF FOLIC ACID IN PREGNANCY:-
THE benefit of folic acid supplementation to pregnant women has long been establish to prevent the development of megaloblastic anemia, particularly among the populations with low dietary folate.
Low dietary intake of folic acid is known to increase the risk for delivery of a child with a Neural Tube Defects (NTD)
Preconceptional folic acid supplementation significantly reduces the occurrence of NTD.
Supplementation/ supplementational folic acid intake during pregnancy results in increased infant birth weight and improved apgar scores, along with a concomitant decreased incidence of fetal growth retardation and maternal infections.
It is very well-established that folic acid functions primarily as a methyl group donar involved in mechanism or many important body processes, including DNA synthesis.
This mechanism may be perturbed in NTD’S and consequently adequate levels of folic acid intake are very essential in pregnant women.
Periconceptional folic acid supplementation significantly reduces the occurrence of NTD.
Supplemental folic acid intake during pregnancy results in increased infant birth weight and improved Apgar scores, along with a concomitant decreased incidence of fetal growth retardation and maternal infections.
