Monohydrate, pentahydrate and hexahydrate forms are relatively rare. In addition to blue-green colour crystals, other forms of ferrous sulfate are mostly white coloured crystals. When heated, the hydrated crystals lose water and become anhydrous solids. Upon further heating, it is decomposed into sulfur dioxide, sulfur trioxide and iron III oxide reddish-brown colour. They are odourless crystals. Ferrous sulfate is used to treat conditions of iron deficiencies like iron deficiency anaemia.
It is also added to plants, as well. In conditions like iron chlorosis, where plant leaves become yellow, pale colour ferrous is given. Moreover, it is used as a precursor to synthesize other compounds.
Since it is a reduction agent, it is used for redox reactions, as well. In ferrous gluconate, the ferrous anion is combined with an organic anion.
Blood levels should be rechecked periodically, and supplements discontinued or taken at a lower dosage if levels return to normal, as long-term high dosages can lead to constipation or other digestive upset. Anemia of chronic disease AOCD occurs not from a low iron intake but with conditions that cause inflammation in the body, such as infections, cancer, kidney disease, inflammatory bowel disease, heart failure, lupus, and rheumatoid arthritis. The body may actually contain normal amounts of iron, but levels in the blood are very low.
Treatment for AOCD focuses on treating the inflammatory condition. Increasing iron in the diet typically does not help. If the inflammation or condition improves, the anemia will usually decrease as well. In rare severe cases, a blood transfusion can be given to quickly boost the amount of hemoglobin in the blood.
Toxicity is rare because the body regulates iron absorption and will absorb less if iron stores are adequate. Some people have a hereditary condition called hemochromatosis that causes an excessive buildup of iron in the body.
Treatments are given periodically to remove blood or excess iron in the blood. People with hemochromatosis are educated to follow a low-iron diet and to avoid iron and vitamin C supplements. If left untreated, iron can build up in certain organs so that there is a higher risk of developing conditions like liver cirrhosis, liver cancer, or heart disease.
Try this easy dish that can boost iron levels by combining foods rich in non-heme iron and vitamin C:. The contents of this website are for educational purposes and are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
The Nutrition Source does not recommend or endorse any products. Skip to content The Nutrition Source. Harvard T. The Nutrition Source Menu. Patients exhibiting signs of iron-deficiency anemia should be encouraged to seek medical evaluation by their primary health care provider to prevent further complications. In addition, patients exhibiting signs of anemia who are not pregnant, breast-feeding, or menstruating, or are not on a meat-restricted diet should always seek medical evaluation because anemia may be a symptom of a more serious medical condition.
Nonprescription iron supplements are available as ferrous salts and ferric salts Table 3. Ferrous salt formulations may be administered with ascorbic acid to improve absorption. Some clinicians may advise patients to take iron supplements with fruit juices high in ascorbic acid to improve absorption.
Some combination products contain iron and ascorbic acid, such as Vitron-C Insight Pharmaceuticals , which is formulated to help the body absorb iron more effectively and to cause less constipation.
If iron supplementation is warranted, clinicians should consider which product is best for the individual patient, how well the iron is absorbed and tolerated, the dosing intervals, and the amount of elemental iron delivered per dose. Patients concerned about iron deficiency should not use iron supplements until they have been evaluated by their primary health care provider to ensure that supplementation is appropriate.
When patients are counseled about iron supplementation, it is important to remind them that iron supplements may be associated with GI irritation, nausea, constipation, dark stools, and abdominal pain. Patients should be reminded that iron supplements should only be taken as directed under the supervision of their primary health care provider.
Patients should be encouraged to contact their primary health care provider if they experience any adverse effects or their symptoms worsen. Serum ferritin concentration, a measure of the body's iron stores, is currently the most efficient and cost-effective test for diagnosing iron deficiency [ ].
Because serum ferritin decreases during the first stage of iron depletion, it can identify low iron status before the onset of IDA [ 7 , 9 , 14 ]. However, serum ferritin is subject to influence by inflammation due, for example, to infectious disease , which elevates serum ferritin concentrations [ 16 ].
Hemoglobin and hematocrit tests are the most commonly used measures to screen patients for iron deficiency, even though they are neither sensitive nor specific [ 5 , 7 , 17 ]. Often, hemoglobin concentrations are combined with serum ferritin measurements to identify IDA [ 7 ].
DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and gender, include:. Table 1 lists the current iron RDAs for nonvegetarians.
The RDAs for vegetarians are 1. This is because heme iron from meat is more bioavailable than nonheme iron from plant-based foods, and meat, poultry, and seafood increase the absorption of nonheme iron [ 5 ]. For infants from birth to 6 months, the FNB established an AI for iron that is equivalent to the mean intake of iron in healthy, breastfed infants. The richest sources of heme iron in the diet include lean meat and seafood [ 19 ]. Dietary sources of nonheme iron include nuts, beans, vegetables, and fortified grain products.
In the United States, about half of dietary iron comes from bread, cereal, and other grain products [ 2 , 3 , 5 ]. Breast milk contains highly bioavailable iron but in amounts that are not sufficient to meet the needs of infants older than 4 to 6 months [ 2 , 20 ]. In the United States, Canada, and many other countries, wheat and other flours are fortified with iron [ 21 , 22 ]. Infant formulas are fortified with 12 mg iron per liter [ 20 ]. Heme iron has higher bioavailability than nonheme iron, and other dietary components have less effect on the bioavailability of heme than nonheme iron [ 3 , 4 ].
In addition to ascorbic acid, meat, poultry, and seafood can enhance nonheme iron absorption, whereas phytate present in grains and beans and certain polyphenols in some non-animal foods such as cereals and legumes have the opposite effect [ 4 ]. Unlike other inhibitors of iron absorption, calcium might reduce the bioavailability of both nonheme and heme iron.
Several food sources of iron are listed in Table 2. Some plant-based foods that are good sources of iron, such as spinach, have low iron bioavailability because they contain iron-absorption inhibitors, such as polyphenols [ 23 , 24 ]. The U. Food and Drug Administration FDA developed DVs to help consumers compare the nutrient contents of foods and dietary supplements within the context of a total diet.
The DV for iron is 18 mg for adults and children age 4 years and older [ 26 ]. FDA requires food labels to list iron content. Iron is available in many dietary supplements. Frequently used forms of iron in supplements include ferrous and ferric iron salts, such as ferrous sulfate, ferrous gluconate, ferric citrate, and ferric sulfate [ 3 , 27 ].
Because of its higher solubility, ferrous iron in dietary supplements is more bioavailable than ferric iron [ 3 ]. Other forms of supplemental iron, such as heme iron polypeptides, carbonyl iron, iron amino-acid chelates, and polysaccharide-iron complexes, might have fewer gastrointestinal side effects than ferrous or ferric salts [ 27 ].
The different forms of iron in supplements contain varying amounts of elemental iron. Fortunately, elemental iron is listed in the Supplement Facts panel, so consumers do not need to calculate the amount of iron supplied by various forms of iron supplements. Calcium might interfere with the absorption of iron, although this effect has not been definitively established [ 4 , 31 ]. For this reason, some experts suggest that people take individual calcium and iron supplements at different times of the day [ 32 ].
People in the United States usually obtain adequate amounts of iron from their diets, but infants, young children, teenaged girls, pregnant women, and premenopausal women are at risk of obtaining insufficient amounts [ 28 , ]. The average daily iron intake from foods is The average daily iron intake from foods and supplements is The median dietary iron intake in pregnant women is Rates of iron deficiency vary by race and other sociodemographic factors.
Deficiency including IDA is more common among children and adolescents in food-insecure households than in food-secure households [ 36 , 37 ]. Among pregnant women, deficiency based on depleted iron stores is more common in Mexican American Some groups are at risk of obtaining excess iron.
Individuals with hereditary hemochromatosis, which predisposes them to absorb excessive amounts of dietary iron, have an increased risk of iron overload [ 39 ]. One study suggests that elderly people are more likely to have chronic positive iron balance and elevated total body iron than iron deficiency.
The authors did not assess genotypes, so they could not determine whether these results were due to hemochromatosis [ 40 ]. Iron deficiency is not uncommon in the United States, especially among young children, women of reproductive age, and pregnant women. Because iron deficiency is associated with poor diet, malabsorptive disorders, and blood loss, people with iron deficiency usually have other nutrient deficiencies [ 2 ]. In developing countries, iron deficiency often results from enteropathies and blood loss associated with gastrointestinal parasites [ 2 ].
Iron depletion and deficiency progresses through several stages [ ]:. Although iron deficiency is the most common cause of anemia, deficiencies of other micronutrients such as folate and vitamin B12 and other factors such as chronic infection and inflammation can cause different forms of anemia or contribute to their severity. The functional deficits associated with IDA include gastrointestinal disturbances; weakness; fatigue; difficulty concentrating; and impaired cognitive function, immune function, exercise or work performance, and body temperature regulation [ 15 , 43 ].
In infants and children, IDA can result in psychomotor and cognitive abnormalities that, without treatment, can lead to learning difficulties [ 2 , 43 ]. Some evidence indicates that the effects of deficiencies early in life persist through adulthood [ 2 ]. Because iron deficiency is often accompanied by deficiencies of other nutrients, the signs and symptoms of iron deficiency can be difficult to isolate [ 2 ]. During pregnancy, plasma volume and red cell mass expand due to dramatic increases in maternal red blood cell production [ 2 ].
As a result of this expansion and to meet the needs of the fetus and placenta, the amount of iron that women need increases during pregnancy. Iron deficiency during pregnancy increases the risk of maternal and infant mortality, premature birth, and low birthweight [ 44 ]. Infants—especially those born preterm or with low birthweight or whose mothers have iron deficiency—are at risk of iron deficiency because of their high iron requirements due to their rapid growth [ 34 , 45 ].
Full-term infants usually have sufficient iron stores and need little if any iron from external sources until they are 4 to 6 months old [ 2 ]. However, full-term infants have a risk of becoming iron deficient at 6 to 9 months unless they obtain adequate amounts of solid foods that are rich in bioavailable iron or iron-fortified formula. Women of reproductive age who have menorrhagia, or abnormally heavy bleeding during menstruation, are at increased risk of iron deficiency.
Women with menorrhagia lose significantly more iron per menstrual cycle on average than women with normal menstrual bleeding [ 49 ]. Frequent blood donors have an increased risk of iron deficiency [ 5 ]. In the United States, adults may donate blood as often as every 8 weeks, which can deplete iron stores. In a study of 2, blood donors, men who had given at least three and women who had given at least two whole-blood donations in the previous year were more than five times as likely to have depleted iron stores as first-time donors [ 53 ].
A clinical trial of iron supplementation found that of adults who had donated a unit of blood within the past 3—8 days, those randomized to take an iron supplement Without iron supplementation, two-thirds of the donors had not recovered the iron they lost, even after 24 weeks. The main causes of iron deficiency in people with cancer are anemia of chronic disease discussed in the Iron and Health section below and chemotherapy-induced anemia. However, chronic blood loss and deficiencies of other nutrients due, for example, to cancer-induced anorexia can exacerbate iron deficiency in this population.
The combination of low iron intake and high iron loss can lead to a negative iron balance; reduced production of hemoglobin; or microcytic, hypochromic anemia [ 58 ]. Potential causes of iron deficiency in people with heart failure include poor nutrition, malabsorption, defective mobilization of iron stores, cardiac cachexia, and use of aspirin and oral anticoagulants, which might result in the loss of some blood in the gastrointestinal tract [ 61 ].
This section focuses on the role of iron in IDA in pregnant women, infants, and toddlers, as well as in anemia of chronic disease. Rates of deficiency were 6. Randomized controlled trials have shown that iron supplementation can prevent IDA in pregnant women and related adverse consequences in their infants [ 66 , 67 ].
In the same review, use of daily iron supplements was associated with an 8. In addition, mean birthweight was 31 g higher for infants whose mothers took daily iron supplements during pregnancy compared with the infants of mothers who did not take iron. Guidelines on iron supplementation during pregnancy vary, but many recommend some form of iron supplementation to prevent IDA:. The IOM notes that because the median intake of dietary iron by pregnant women is well below the EAR, pregnant women need iron supplementation [ 5 ].
The Dietary Guidelines for Americans advises that women who are pregnant take an iron supplement when recommended by an obstetrician or other health-care provider [ 19 ]. It adds that low intakes of iron are a public health concern for pregnant women. The prevalence of IDA in U. Full-term infants typically have adequate iron stores for approximately the first 4 to 6 months, but the risk of iron deficiency in low-birthweight and preterm infants begins at birth because of their low iron stores.
IDA in infancy can lead to adverse cognitive and psychological effects, including delayed attention and social withdrawal; some of these effects might be irreversible [ 2 , 20 ].
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