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NCP Miracle II
161 Richardson-Bass Rd
Kenly, NC 27542
Tel:(919)284-6002 Fax:(919)284-4197
EMail: info1@ncpmiracle2.com
161 Richardson-Bass Rd
Kenly, NC 27542
Tel:(919)284-6002 Fax:(919)284-4197
EMail: info1@ncpmiracle2.com
| Iron |
Iron: What is it?
Iron, one of the most abundant metals on Earth, is essential to most life forms and to normal
human physiology. Iron is an integral part of many proteins and enzymes that maintain good
health. In humans, iron is an essential component of proteins involved in oxygen transport
[1,2]. It is also essential for the regulation of cell growth and differentiation [3,4]. A
deficiency of iron limits oxygen delivery to cells, resulting in fatigue, poor work
performance, and decreased immunity [1,5-6]. On the other hand, excess amounts of iron
can result in toxicity and even death [7].
Almost two-thirds of iron in the body is found in hemoglobin, the protein in red blood cells
that carries oxygen to tissues. Smaller amounts of iron are found in myoglobin, a protein
that helps supply oxygen to muscle, and in enzymes that assist biochemical reactions. Iron
is also found in proteins that store iron for future needs and that transport iron in blood.
Iron stores are regulated by intestinal iron absorption [1,8].
What foods provide iron?
There are two forms of dietary iron: heme and nonheme. Heme iron is derived from
hemoglobin, the protein in red blood cells that delivers oxygen to cells. Heme iron is found
in animal foods that originally contained hemoglobin, such as red meats, fish, and poultry.
Iron in plant foods such as lentils and beans is arranged in a chemical structure called
nonheme iron [9]. This is the form of iron added to iron-enriched and iron-fortified foods.
Heme iron is absorbed better than nonheme iron, but most dietary iron is nonheme iron [8].
What affects iron absorption?
Iron absorption refers to the amount of dietary iron that the body obtains and uses from
food. Healthy adults absorb about 10% to 15% of dietary iron, but individual absorption is
influenced by several factors [1,3,8,11-15].
Storage levels of iron have the greatest influence on iron absorption. Iron absorption
increases when body stores are low. When iron stores are high, absorption decreases to
help protect against toxic effects of iron overload [1,3]. Iron absorption is also influenced by
the type of dietary iron consumed. Absorption of heme iron from meat proteins is efficient.
Absorption of heme iron ranges from 15% to 35%, and is not significantly affected by diet
[15]. In contrast, 2% to 20% of nonheme iron in plant foods such as rice, maize, black beans,
soybeans and wheat is absorbed [16]. Nonheme iron absorption is significantly influenced
by various food components [1,3,11-15].
Meat proteins and vitamin C will improve the absorption of nonheme iron [1,17-18]. Tannins
(found in tea), calcium, polyphenols, and phytates (found in legumes and whole grains) can
decrease absorption of nonheme iron [1,19-24]. Some proteins found in soybeans also
inhibit nonheme iron absorption [1,25]. It is most important to include foods that enhance
nonheme iron absorption when daily iron intake is less than recommended, when iron
losses are high (which may occur with heavy menstrual losses), when iron requirements are
high (as in pregnancy), and when only vegetarian nonheme sources of iron are consumed.
Iron in human breast milk is well absorbed by infants. It is estimated that infants can use
greater than 50% of the iron in breast milk as compared to less than 12% of the iron in infant
formula [1]. The amount of iron in cow's milk is low, and infants poorly absorb it. Feeding
cow's milk to infants also may result in gastrointestinal bleeding. For these reasons, cow's
milk should not be fed to infants until they are at least 1 year old [1]. The American Academy
of Pediatrics (AAP) recommends that infants be exclusively breast fed for the first six
months of life. Gradual introduction of iron-enriched solid foods should complement breast
milk from 7 to 12 months of age [26]. Infants weaned from breast milk before 12 months of
age should receive iron-fortified infant formula [26]. Infant formulas that contain from 4 to 12
milligrams of iron per liter are considered iron-fortified [27].
Data from the National Health and Nutrition Examination Survey (NHANES) describe dietary
intake of Americans 2 months of age and older. NHANES (1988-94) data suggest that males of
all racial and ethnic groups consume recommended amounts of iron. However, iron intakes
are generally low in females of childbearing age and young children [28-29].
Researchers also examine specific groups within the NHANES population. For example,
researchers have compared dietary intakes of adults who consider themselves to be food
insufficient (and therefore have limited access to nutritionally adequate foods) to those who
are food sufficient (and have easy access to food). Older adults from food insufficient
families had significantly lower intakes of iron than older adults who are food sufficient. In
one survey, twenty percent of adults age 20 to 59 and 13.6% of adults age 60 and older from
food insufficient families consumed less than 50% of the RDA for iron, as compared to 13% of
adults age 20 to 50 and 2.5% of adults age 60 and older from food sufficient families [30].
Iron intake is negatively influenced by low nutrient density foods, which are high in calories
but low in vitamins and minerals. Sugar sweetened sodas and most desserts are examples
of low nutrient density foods, as are snack foods such as potato chips. Among almost 5,000
children and adolescents between the ages of 8 and 18 who were surveyed, low nutrient
density foods contributed almost 30% of daily caloric intake, with sweeteners and desserts
jointly accounting for almost 25% of caloric intake. Those children and adolescents who
consumed fewer "low nutrient density" foods were more likely to consume recommended
amounts of iron [31].
Data from The Continuing Survey of Food Intakes by Individuals (CSFII1994-6 and 1998) was
used to examine the effect of major food and beverage sources of added sugars on
micronutrient intake of U.S. children aged 6 to 17 years. Researchers found that
consumption of presweetened cereals, which are fortified with iron, increased the
likelihood of meeting recommendations for iron intake. On the other hand, as intake of
sugar-sweetened beverages, sugars, sweets, and sweetened grains increased, children
were less likely to consume recommended amounts of iron [32].
When can iron deficiency occur?
The World Health Organization considers iron deficiency the number one nutritional
disorder in the world [33]. As many as 80% of the world's population may be iron deficient,
while 30% may have iron deficiency anemia [34].
Iron deficiency develops gradually and usually begins with a negative iron balance, when
iron intake does not meet the daily need for dietary iron. This negative balance initially
depletes the storage form of iron while the blood hemoglobin level, a marker of iron status,
remains normal. Iron deficiency anemia is an advanced stage of iron depletion. It occurs
when storage sites of iron are deficient and blood levels of iron cannot meet daily needs.
Blood hemoglobin levels are below normal with iron deficiency anemia [1].
Iron deficiency anemia can be associated with low dietary intake of iron, inadequate
absorption of iron, or excessive blood loss [1,16,35]. Women of childbearing age, pregnant
women, preterm and low birth weight infants, older infants and toddlers, and teenage girls
are at greatest risk of developing iron deficiency anemia because they have the greatest
need for iron [33]. Women with heavy menstrual losses can lose a significant amount of iron
and are at considerable risk for iron deficiency [1,3]. Adult men and post-menopausal
women lose very little iron, and have a low risk of iron deficiency.
Individuals with kidney failure, especially those being treated with dialysis, are at high risk
for developing iron deficiency anemia. This is because their kidneys cannot create enough
erythropoietin, a hormone needed to make red blood cells. Both iron and erythropoietin can
be lost during kidney dialysis. Individuals who receive routine dialysis treatments usually
need extra iron and synthetic erythropoietin to prevent iron deficiency [36-38].
Vitamin A helps mobilize iron from its storage sites, so a deficiency of vitamin A limits the
body's ability to use stored iron. This results in an "apparent" iron deficiency because
hemoglobin levels are low even though the body can maintain normal amounts of stored
iron [39-40]. While uncommon in the U.S., this problem is seen in developing countries
where vitamin A deficiency often occurs.
Chronic malabsorption can contribute to iron depletion and deficiency by limiting dietary
iron absorption or by contributing to intestinal blood loss. Most iron is absorbed in the small
intestines. Gastrointestinal disorders that result in inflammation of the small intestine may
result in diarrhea, poor absorption of dietary iron, and iron depletion [41].
Signs of iron deficiency anemia include [1,5-6,42]:
feeling tired and weak
decreased work and school performance
slow cognitive and social development during childhood
difficulty maintaining body temperature
decreased immune function, which increases susceptibility to infection
glossitis (an inflamed tongue)
Eating nonnutritive substances such as dirt and clay, often referred to as pica or geophagia,
is sometimes seen in persons with iron deficiency. There is disagreement about the cause
of this association. Some researchers believe that these eating abnormalities may result in
an iron deficiency. Other researchers believe that iron deficiency may somehow increase
the likelihood of these eating problems [43-44].
People with chronic infectious, inflammatory, or malignant disorders such as arthritis and
cancer may become anemic. However, the anemia that occurs with inflammatory disorders
differs from iron deficiency anemia and may not respond to iron supplements [45-47].
Research suggests that inflammation may over-activate a protein involved in iron
metabolism. This protein may inhibit iron absorption and reduce the amount of iron
circulating in blood, resulting in anemia [48].
Who may need extra iron to prevent a deficiency?
Three groups of people are most likely to benefit from iron supplements: people with a
greater need for iron, individuals who tend to lose more iron, and people who do not absorb
iron normally. These individuals include [1,36-38,41,49-57]:
pregnant women
preterm and low birth weight infants
older infants and toddlers
teenage girls
women of childbearing age, especially those with heavy menstrual losses
people with renal failure, especially those undergoing routine dialysis
people with gastrointestinal disorders who do not absorb iron normally
Celiac Disease and Crohn's Syndrome are associated with gastrointestinal malabsorption
and may impair iron absorption. Iron supplementation may be needed if these conditions
result in iron deficiency anemia [41].
Women taking oral contraceptives may experience less bleeding during their periods and
have a lower risk of developing an iron deficiency. Women who use an intrauterine device
(IUD) to prevent pregnancy may experience more bleeding and have a greater risk of
developing an iron deficiency. If laboratory tests indicate iron deficiency anemia, iron
supplements may be recommended.
Total dietary iron intake in vegetarian diets may meet recommended levels; however that
iron is less available for absorption than in diets that include meat [58]. Vegetarians who
exclude all animal products from their diet may need almost twice as much dietary iron each
day as non-vegetarians because of the lower intestinal absorption of nonheme iron in plant
foods [1]. Vegetarians should consider consuming nonheme iron sources together with a
good source of vitamin C, such as citrus fruits, to improve the absorption of nonheme iron
[1].
There are many causes of anemia, including iron deficiency. There are also several potential
causes of iron deficiency. After a thorough evaluation, physicians can diagnose the cause of
anemia and prescribe the appropriate treatment.
Does pregnancy increase the need for iron?
Nutrient requirements increase during pregnancy to support fetal growth and maternal
health. Iron requirements of pregnant women are approximately double that of
non-pregnant women because of increased blood volume during pregnancy, increased
needs of the fetus, and blood losses that occur during delivery [16]. If iron intake does not
meet increased requirements, iron deficiency anemia can occur. Iron deficiency anemia of
pregnancy is responsible for significant morbidity, such as premature deliveries and giving
birth to infants with low birth weight [1,51,59-62].
Low levels of hemoglobin and hematocrit may indicate iron deficiency. Hemoglobin is the
protein in red blood cells that carries oxygen to tissues. Hematocrit is the proportion of
whole blood that is made up of red blood cells. Nutritionists estimate that over half of
pregnant women in the world may have hemoglobin levels consistent with iron deficiency.
In the U.S., the Centers for Disease Control (CDC) estimated that 12% of all women age 12 to
49 years were iron deficient in 1999-2000. When broken down by groups, 10% of
non-Hispanic white women, 22% of Mexican-American women, and 19% of non-Hispanic black
women were iron deficient. Prevalence of iron deficiency anemia among lower income
pregnant women has remained the same, at about 30%, since the 1980s [63].
The RDA for iron for pregnant women increases to 27 mg per day. Unfortunately, data from
the 1988-94 NHANES survey suggested that the median iron intake among pregnant women
was approximately 15 mg per day [1]. When median iron intake is less than the RDA, more
than half of the group consumes less iron than is recommended each day.
Several major health organizations recommend iron supplementation during pregnancy to
help pregnant women meet their iron requirements. The CDC recommends routine low-dose
iron supplementation (30 mg/day) for all pregnant women, beginning at the first prenatal
visit [33]. When a low hemoglobin or hematocrit is confirmed by repeat testing, the CDC
recommends larger doses of supplemental iron. The Institute of Medicine of the National
Academy of Sciences also supports iron supplementation during pregnancy [1].
Obstetricians often monitor the need for iron supplementation during pregnancy and
provide individualized recommendations to pregnant women.
Iron, one of the most abundant metals on Earth, is essential to most life forms and to normal
human physiology. Iron is an integral part of many proteins and enzymes that maintain good
health. In humans, iron is an essential component of proteins involved in oxygen transport
[1,2]. It is also essential for the regulation of cell growth and differentiation [3,4]. A
deficiency of iron limits oxygen delivery to cells, resulting in fatigue, poor work
performance, and decreased immunity [1,5-6]. On the other hand, excess amounts of iron
can result in toxicity and even death [7].
Almost two-thirds of iron in the body is found in hemoglobin, the protein in red blood cells
that carries oxygen to tissues. Smaller amounts of iron are found in myoglobin, a protein
that helps supply oxygen to muscle, and in enzymes that assist biochemical reactions. Iron
is also found in proteins that store iron for future needs and that transport iron in blood.
Iron stores are regulated by intestinal iron absorption [1,8].
What foods provide iron?
There are two forms of dietary iron: heme and nonheme. Heme iron is derived from
hemoglobin, the protein in red blood cells that delivers oxygen to cells. Heme iron is found
in animal foods that originally contained hemoglobin, such as red meats, fish, and poultry.
Iron in plant foods such as lentils and beans is arranged in a chemical structure called
nonheme iron [9]. This is the form of iron added to iron-enriched and iron-fortified foods.
Heme iron is absorbed better than nonheme iron, but most dietary iron is nonheme iron [8].
What affects iron absorption?
Iron absorption refers to the amount of dietary iron that the body obtains and uses from
food. Healthy adults absorb about 10% to 15% of dietary iron, but individual absorption is
influenced by several factors [1,3,8,11-15].
Storage levels of iron have the greatest influence on iron absorption. Iron absorption
increases when body stores are low. When iron stores are high, absorption decreases to
help protect against toxic effects of iron overload [1,3]. Iron absorption is also influenced by
the type of dietary iron consumed. Absorption of heme iron from meat proteins is efficient.
Absorption of heme iron ranges from 15% to 35%, and is not significantly affected by diet
[15]. In contrast, 2% to 20% of nonheme iron in plant foods such as rice, maize, black beans,
soybeans and wheat is absorbed [16]. Nonheme iron absorption is significantly influenced
by various food components [1,3,11-15].
Meat proteins and vitamin C will improve the absorption of nonheme iron [1,17-18]. Tannins
(found in tea), calcium, polyphenols, and phytates (found in legumes and whole grains) can
decrease absorption of nonheme iron [1,19-24]. Some proteins found in soybeans also
inhibit nonheme iron absorption [1,25]. It is most important to include foods that enhance
nonheme iron absorption when daily iron intake is less than recommended, when iron
losses are high (which may occur with heavy menstrual losses), when iron requirements are
high (as in pregnancy), and when only vegetarian nonheme sources of iron are consumed.
Iron in human breast milk is well absorbed by infants. It is estimated that infants can use
greater than 50% of the iron in breast milk as compared to less than 12% of the iron in infant
formula [1]. The amount of iron in cow's milk is low, and infants poorly absorb it. Feeding
cow's milk to infants also may result in gastrointestinal bleeding. For these reasons, cow's
milk should not be fed to infants until they are at least 1 year old [1]. The American Academy
of Pediatrics (AAP) recommends that infants be exclusively breast fed for the first six
months of life. Gradual introduction of iron-enriched solid foods should complement breast
milk from 7 to 12 months of age [26]. Infants weaned from breast milk before 12 months of
age should receive iron-fortified infant formula [26]. Infant formulas that contain from 4 to 12
milligrams of iron per liter are considered iron-fortified [27].
Data from the National Health and Nutrition Examination Survey (NHANES) describe dietary
intake of Americans 2 months of age and older. NHANES (1988-94) data suggest that males of
all racial and ethnic groups consume recommended amounts of iron. However, iron intakes
are generally low in females of childbearing age and young children [28-29].
Researchers also examine specific groups within the NHANES population. For example,
researchers have compared dietary intakes of adults who consider themselves to be food
insufficient (and therefore have limited access to nutritionally adequate foods) to those who
are food sufficient (and have easy access to food). Older adults from food insufficient
families had significantly lower intakes of iron than older adults who are food sufficient. In
one survey, twenty percent of adults age 20 to 59 and 13.6% of adults age 60 and older from
food insufficient families consumed less than 50% of the RDA for iron, as compared to 13% of
adults age 20 to 50 and 2.5% of adults age 60 and older from food sufficient families [30].
Iron intake is negatively influenced by low nutrient density foods, which are high in calories
but low in vitamins and minerals. Sugar sweetened sodas and most desserts are examples
of low nutrient density foods, as are snack foods such as potato chips. Among almost 5,000
children and adolescents between the ages of 8 and 18 who were surveyed, low nutrient
density foods contributed almost 30% of daily caloric intake, with sweeteners and desserts
jointly accounting for almost 25% of caloric intake. Those children and adolescents who
consumed fewer "low nutrient density" foods were more likely to consume recommended
amounts of iron [31].
Data from The Continuing Survey of Food Intakes by Individuals (CSFII1994-6 and 1998) was
used to examine the effect of major food and beverage sources of added sugars on
micronutrient intake of U.S. children aged 6 to 17 years. Researchers found that
consumption of presweetened cereals, which are fortified with iron, increased the
likelihood of meeting recommendations for iron intake. On the other hand, as intake of
sugar-sweetened beverages, sugars, sweets, and sweetened grains increased, children
were less likely to consume recommended amounts of iron [32].
When can iron deficiency occur?
The World Health Organization considers iron deficiency the number one nutritional
disorder in the world [33]. As many as 80% of the world's population may be iron deficient,
while 30% may have iron deficiency anemia [34].
Iron deficiency develops gradually and usually begins with a negative iron balance, when
iron intake does not meet the daily need for dietary iron. This negative balance initially
depletes the storage form of iron while the blood hemoglobin level, a marker of iron status,
remains normal. Iron deficiency anemia is an advanced stage of iron depletion. It occurs
when storage sites of iron are deficient and blood levels of iron cannot meet daily needs.
Blood hemoglobin levels are below normal with iron deficiency anemia [1].
Iron deficiency anemia can be associated with low dietary intake of iron, inadequate
absorption of iron, or excessive blood loss [1,16,35]. Women of childbearing age, pregnant
women, preterm and low birth weight infants, older infants and toddlers, and teenage girls
are at greatest risk of developing iron deficiency anemia because they have the greatest
need for iron [33]. Women with heavy menstrual losses can lose a significant amount of iron
and are at considerable risk for iron deficiency [1,3]. Adult men and post-menopausal
women lose very little iron, and have a low risk of iron deficiency.
Individuals with kidney failure, especially those being treated with dialysis, are at high risk
for developing iron deficiency anemia. This is because their kidneys cannot create enough
erythropoietin, a hormone needed to make red blood cells. Both iron and erythropoietin can
be lost during kidney dialysis. Individuals who receive routine dialysis treatments usually
need extra iron and synthetic erythropoietin to prevent iron deficiency [36-38].
Vitamin A helps mobilize iron from its storage sites, so a deficiency of vitamin A limits the
body's ability to use stored iron. This results in an "apparent" iron deficiency because
hemoglobin levels are low even though the body can maintain normal amounts of stored
iron [39-40]. While uncommon in the U.S., this problem is seen in developing countries
where vitamin A deficiency often occurs.
Chronic malabsorption can contribute to iron depletion and deficiency by limiting dietary
iron absorption or by contributing to intestinal blood loss. Most iron is absorbed in the small
intestines. Gastrointestinal disorders that result in inflammation of the small intestine may
result in diarrhea, poor absorption of dietary iron, and iron depletion [41].
Signs of iron deficiency anemia include [1,5-6,42]:
feeling tired and weak
decreased work and school performance
slow cognitive and social development during childhood
difficulty maintaining body temperature
decreased immune function, which increases susceptibility to infection
glossitis (an inflamed tongue)
Eating nonnutritive substances such as dirt and clay, often referred to as pica or geophagia,
is sometimes seen in persons with iron deficiency. There is disagreement about the cause
of this association. Some researchers believe that these eating abnormalities may result in
an iron deficiency. Other researchers believe that iron deficiency may somehow increase
the likelihood of these eating problems [43-44].
People with chronic infectious, inflammatory, or malignant disorders such as arthritis and
cancer may become anemic. However, the anemia that occurs with inflammatory disorders
differs from iron deficiency anemia and may not respond to iron supplements [45-47].
Research suggests that inflammation may over-activate a protein involved in iron
metabolism. This protein may inhibit iron absorption and reduce the amount of iron
circulating in blood, resulting in anemia [48].
Who may need extra iron to prevent a deficiency?
Three groups of people are most likely to benefit from iron supplements: people with a
greater need for iron, individuals who tend to lose more iron, and people who do not absorb
iron normally. These individuals include [1,36-38,41,49-57]:
pregnant women
preterm and low birth weight infants
older infants and toddlers
teenage girls
women of childbearing age, especially those with heavy menstrual losses
people with renal failure, especially those undergoing routine dialysis
people with gastrointestinal disorders who do not absorb iron normally
Celiac Disease and Crohn's Syndrome are associated with gastrointestinal malabsorption
and may impair iron absorption. Iron supplementation may be needed if these conditions
result in iron deficiency anemia [41].
Women taking oral contraceptives may experience less bleeding during their periods and
have a lower risk of developing an iron deficiency. Women who use an intrauterine device
(IUD) to prevent pregnancy may experience more bleeding and have a greater risk of
developing an iron deficiency. If laboratory tests indicate iron deficiency anemia, iron
supplements may be recommended.
Total dietary iron intake in vegetarian diets may meet recommended levels; however that
iron is less available for absorption than in diets that include meat [58]. Vegetarians who
exclude all animal products from their diet may need almost twice as much dietary iron each
day as non-vegetarians because of the lower intestinal absorption of nonheme iron in plant
foods [1]. Vegetarians should consider consuming nonheme iron sources together with a
good source of vitamin C, such as citrus fruits, to improve the absorption of nonheme iron
[1].
There are many causes of anemia, including iron deficiency. There are also several potential
causes of iron deficiency. After a thorough evaluation, physicians can diagnose the cause of
anemia and prescribe the appropriate treatment.
Does pregnancy increase the need for iron?
Nutrient requirements increase during pregnancy to support fetal growth and maternal
health. Iron requirements of pregnant women are approximately double that of
non-pregnant women because of increased blood volume during pregnancy, increased
needs of the fetus, and blood losses that occur during delivery [16]. If iron intake does not
meet increased requirements, iron deficiency anemia can occur. Iron deficiency anemia of
pregnancy is responsible for significant morbidity, such as premature deliveries and giving
birth to infants with low birth weight [1,51,59-62].
Low levels of hemoglobin and hematocrit may indicate iron deficiency. Hemoglobin is the
protein in red blood cells that carries oxygen to tissues. Hematocrit is the proportion of
whole blood that is made up of red blood cells. Nutritionists estimate that over half of
pregnant women in the world may have hemoglobin levels consistent with iron deficiency.
In the U.S., the Centers for Disease Control (CDC) estimated that 12% of all women age 12 to
49 years were iron deficient in 1999-2000. When broken down by groups, 10% of
non-Hispanic white women, 22% of Mexican-American women, and 19% of non-Hispanic black
women were iron deficient. Prevalence of iron deficiency anemia among lower income
pregnant women has remained the same, at about 30%, since the 1980s [63].
The RDA for iron for pregnant women increases to 27 mg per day. Unfortunately, data from
the 1988-94 NHANES survey suggested that the median iron intake among pregnant women
was approximately 15 mg per day [1]. When median iron intake is less than the RDA, more
than half of the group consumes less iron than is recommended each day.
Several major health organizations recommend iron supplementation during pregnancy to
help pregnant women meet their iron requirements. The CDC recommends routine low-dose
iron supplementation (30 mg/day) for all pregnant women, beginning at the first prenatal
visit [33]. When a low hemoglobin or hematocrit is confirmed by repeat testing, the CDC
recommends larger doses of supplemental iron. The Institute of Medicine of the National
Academy of Sciences also supports iron supplementation during pregnancy [1].
Obstetricians often monitor the need for iron supplementation during pregnancy and
provide individualized recommendations to pregnant women.