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Nutrition for Nurses

10.1 The Impact of Nutrition on Hematologic Wellness Across the Lifespan

Nutrition for Nurses10.1 The Impact of Nutrition on Hematologic Wellness Across the Lifespan

Learning Outcomes

By the end of this section, you should be able to:

  • 10.1.1 Describe the impact of nutrition on the hematologic system during pregnancy.
  • 10.1.2 Describe the impact of nutrition on the hematologic system during infancy.
  • 10.1.3 Describe the impact of nutrition on the hematologic system during childhood.
  • 10.1.4 Describe the impact of nutrition on the hematologic system during adolescence.
  • 10.1.5 Describe the impact of nutrition on the hematologic system during adulthood.
  • 10.1.6 Describe the impact of nutrition on the hematologic system during later adulthood.

The most common hematologic consequence throughout the lifespan is anemia, affecting approximately 1.8 billion individuals worldwide (Safiri et al., 2021). Although the specific nutrient responsible for nutritional anemia can vary, the condition is characterized by a deficiency in healthy red blood cells. This can lead to various health conditions and is a major public health issue with significant implications for quality of life, productivity, and mortality.

Less common than anemia, nutritional bleeding disorders are a group of conditions that can lead to problems involving prolonged bleeding and thrombosis caused by a lack of nutrients in the diet, such as vitamin K, vitamin C, or iron. Recognizing signs and symptoms related to these deficiencies is critical to avoid life-threatening complications, particularly during health emergencies such as trauma or sepsis. Although seen less frequently, macronutrient and micronutrient deficiencies can also impair immune system function and tissue healing, effects that can be particularly problematic for individuals living with acute or chronic illnesses such as infections or autoimmune diseases.

Controlling anemia requires an interdisciplinary team to prioritize the highest-risk groups, including young children and clients of reproductive age. Despite the nature of the disease, dietary iron deficiency (ID) is the leading cause of anemia in all regions (Safiri et al., 2021). Recent reports indicate an increased trend in anemia and iron deficiency among pregnant clients and young children over the past two decades (National Center for Health Statistics, 2023). According to the World Health Organization (WHO) criteria, anemia and iron deficiency among pregnant individuals and U.S. children have reached the significance of mild and moderate public health problems, respectively (Jefferds et al., 2022). More attention must therefore be paid to nutritional interventions for these high-risk groups.

Impact on Health During Pregnancy

Red blood cell production increases by 30% during pregnancy to support blood volume expansion and fetal growth (Benson et al., 2022). Iron is preferentially used for erythropoiesis (production of red blood cells); therefore, iron deficits can quickly occur, resulting in maternal and fetal anemia.

Anemia affects approximately 36% of pregnant people worldwide and approximately 12% of pregnant people in the United States. The most common causes of anemia in pregnancy are iron deficiency and acute blood loss (Smith et al., 2019; WHO, n.d.-a). Figure 10.2 is an image of human blood from a case of iron deficiency. If iron needs are not met, there is an increased chance of maternal and fetal adverse outcomes. As the severity of anemia worsens, so do the associated risks, which can result in prolonged hospitalization for postpartum clients (Smith et al., 2019; Jefferds et al., 2022). Clients who have multiple births are twice as likely as those who have single births to develop iron deficiency anemia (IDA) due to increased blood volume expansion and utilization of iron stores.

Anemic blood under the microscope. Most of the smaller red blood cells are pale, although there are a few that are darker. These red blood cells surround the larger white blood cells.
Figure 10.2 Human blood from a case of iron deficiency anemia. The red blood cells are pale and smaller than the larger white blood cells shown in the image. (credit: “This photomicrograph of a Prussian blue stained bone marrow sample, revealed that there was a lack of iron stores. Prussian blue staining for iron particles, which reveals little or no stainable iron in the bone marrow reticulum cells, and normoblasts, is the definitive test for iron deficiency, in the case of iron deficiency anemia (IDA)” by CDC/Dr. Gordon D. McLaren, Public Domain)

The third trimester of pregnancy is the highest risk period of gestation. If the pregnant client has anemia (any type) during pregnancy, they will have a decreased tolerance of blood loss occurring during birth, increasing their risk for hypovolemic shock, heart failure, infection, and the need for blood transfusion (Sharma et al., 2021; Smith et al., 2019). See Table 10.1 for complications and risks associated with anemia in pregnancy.

Race disparities in nutritional anemia exist both globally and within the United States. According to data from the National Health and Nutrition Examination Survey (NHANES), a program conducted by the National Center for Health Statistics to assess the health and nutritional status of adults and children in the United States, non-Hispanic Black pregnant women have the highest prevalence of IDA, particularly during the third trimester of pregnancy (Sharma et al., 2021).

Maternal Risks for Developing Anemia in Pregnancy Maternal Complications of Anemia Fetal Complications of Anemia
  • Maternal age less than 20 years
  • Maternal age greater than 40 years
  • Multiparous
  • Multiple pregnancy
  • In vitro fertilization
  • Underweight before pregnancy
  • Prior cesarean delivery
  • Hypertension
  • Chronic disease
  • Maternal death
  • Cesarean delivery
  • Preeclampsia
  • Placenta previa with hemorrhage
  • Placental abruption
  • Hypovolemic shock
  • Preterm birth
  • Low birth weight
  • Small for gestational age
  • Fetal death
Table 10.1 Complications and Risks Associated with Anemia in Pregnancy

Screening for anemia and ID in pregnant clients to improve maternal and infant health outcomes is a secondary health promotion intervention. The American College of Obstetricians and Gynecologists (2021) now recommends screening for anemia in all pregnant clients at the first prenatal visit and, if detected, screening for iron deficiency. However, current guidelines do not recommend prepregnancy iron screening. This decreases the chance of early identification because individuals may not be aware they are pregnant until later in the pregnancy.

Iron deficiency and IDA are found equally often among pregnant individuals; however, ID alone doubles in the third trimester and might go completely undetected if the client is asymptomatic (Cochrane et. al, 2022; Nour, 2022). Iron requirements gradually increase during pregnancy from 0.8 mg/day to 7.5 mg/day by the third trimester. The average Western diet includes 1–5 mg of iron daily from food sources; therefore, iron stores will be depleted quickly from a pregnant client if not supplemented (Means, 2020). The Centers for Disease Control and Prevention (CDC) recommends 30 mg/day of elemental iron at the start of pregnancy, and the WHO recommends 60 mg/day. If the pregnant client is diagnosed with anemia during pregnancy, iron should be increased to 60–120 mg/day (National Institutes of Health [NIH], 2023; WHO, n.d.-b).

Clinical Tip

Elemental vs. Nonelemental Iron

Elemental iron is a natural substance (heavy metal) directly used by erythrocytes in the body. Nonelemental iron is a chemical compound of iron bound to salt, such as ferrous sulfate. Iron supplements contain an iron salt compound because it is absorbed better than natural iron (Harvard T. H. Chan School of Public Health, 2023). Various iron supplements are available over the counter, which is often confusing for patients and health care professionals. Although health care providers often write prescriptions for iron supplementation, most pharmacies do not carry a “prescription-strength” iron supplement, and clients are directed to over-the-counter products. These product labels will contain two different amounts of iron, elemental and nonelemental; therefore, when providing patient education, nurses must be aware of the amount of elemental iron prescribed and teach clients how to read the labels.

Folate and Vitamin B12 Requirements

Before the United States FDA began mandating folate fortification in 1998, folate (vitamin B9) deficiency was a common cause of anemia during pregnancy (Ismail et al., 2023). Folate demands increase during pregnancy to support fetal and maternal tissue development (Ballestín et al., 2021). Both anemia and folic acid deficiency can place the fetus at risk for neurologic compromise, including defects in brain development and in the myelination of nerve fibers (Jefferds et al., 2022). Although not a common cause of anemia in most women, vitamin B12 deficiency can cause serious maternal-fetal consequences for women with gastrointestinal malabsorption.

Folate and vitamin B12 deficiencies do not always result in macrocytic anemia during pregnancy; however, a physiologic decline is expected (Achebe & Gafter-Gvili, 2017). Folate deficiency in pregnant clients can result in low birth weight and small-for-gestational age (SGA) newborns. Adequate maternal intake of vitamin B12 is necessary to support fetal growth and development. Signs and symptoms of vitamin B12 deficiency include fatigue, pallor, tachycardia, poor exercise tolerance, and suboptimal work performance and should be considered in clients with a history of malabsorption conditions (Achebe & Gafter-Gvili, 2017).

As a primary health promotion intervention, the WHO recommends 400 mcg daily of folic acid in pregnant clients until 3 months postpartum. The CDC recommends 400 mcg/day of folic acid for all individuals of childbearing age to prevent neural tube defects in the event of pregnancy. Prenatal vitamins generally contain 1 mg of folate; however, doses of up to 5 mg/day are recommended for those with higher demands, such as during pregnancy in women who have previously had a pregnancy affected by a neural tube defect (Khan, 2023).

Special Considerations

Vitamin B12 Deficiency

Vitamin B12 is readily stored in excess in the liver, so most pregnant clients are not deficient. However, when vitamin B12 cannot be obtained or absorbed, such as with dietary insufficiency or malabsorption, hepatic stores are depleted, creating a deficiency (Ankar & Kumar, 2022). This includes pregnant clients with a history of a strict vegan diet for the previous 3 years and those who have undergone bariatric surgery. The WHO and the NIH recommend 2.6 mcg of vitamin B12 daily during pregnancy, increasing to 2.8 mcg postpartum if breastfeeding (NIH, 2022).

The risk of developing vitamin B12 deficiency is higher for people who do not get vitamin B12 from their diet, such as those who are vegetarian or vegan and those with health conditions or medication regimens that interfere with absorption of the vitamin:

  • Intestinal diseases
  • Previous gastric or ileac resection
  • History of celiac disease or inflammatory bowel disease
  • Autoimmune disorders (Graves’ disease, thyroiditis, vitiligo)
  • Prolonged use of proton pump inhibitors or H2 receptor antagonists

Clients with a proven deficiency will need higher doses of replacement therapy as follows:

  • Deficiency from diet: 1000 mcg orally once daily
  • Deficiency from malabsorption: 1000 mcg parenterally (intramuscular injection) once every 3–4 weeks (Ankar & Kumar, 2022)


Infancy, from birth to 12 months, is a period of intense physical and developmental growth. Hematopoiesis (formation of blood cellular components) and hemostasis (usual reaction to a bleeding injury to stop blow flow) are incomplete at birth, and micronutrient deficiencies can impair the child’s long-term potential. Requirements for macronutrients and micronutrients are higher during infancy and childhood than other developmental stages and are influenced by the rapid cell division occurring during growth (Physicians Committee for Responsible Medicine, 2020a). Research indicates that micronutrient deficiencies negatively affect the thymus, which can impact lymphocyte function, increasing the risk of infection and inflammatory disease in children (Pai et al., 2018).

Infants receive passive immunity while in utero and through breast milk. This is partially the basis of the American Academy of Pediatrics (AAP) recommendations for breast milk as the “sole source of nutrition for the first 6 months of life, or as long as both mother and baby desire” (Meek et al., 2022). After 6 months, infants should be introduced to supplemental solid foods, including iron-fortified infant cereal. Introducing supplemental foods can be challenging for caregivers, leaving infants and toddlers at additional risk for nutritional deficiencies, especially if food allergies or intolerances are identified. To ensure that infants and young children achieve desirable physical and social milestones, nurses must be well versed in the nutritional considerations affecting this vulnerable population. Educating potential and new parents regarding all health benefits for the breastfed infant is an essential client-centered nursing intervention.

Special Considerations

Infant Benefits of Breastfeeding

According to the AAP Section on Breastfeeding (Meek et al., 2022), exclusive breastfeeding for the first 6 months of an infant’s life can decrease risk for:

  • Acute and chronic infections, including lower respiratory and ear infections and tooth decay
  • Food allergies
  • Sudden infant death syndrome (SIDS)
  • Otitis media
  • Eczema
  • Asthma
  • Childhood and adult obesity
  • Types 1 and 2 diabetes
  • Gastrointestinal discomfort, including vomiting, diarrhea, and colic


According to the WHO, infantile and childhood anemia in the United States ranges from 6–18%, with higher rates among low-income families. As with other age groups, ID is the most common cause of anemia, followed by other nutritional anemias, vitamin B12, and folate (NIH, 2022).

Iron deficiency occurs in 12% of infants ages 6–11 months and 8% of toddlers in the United States. Among toddlers, IDA ranges from 0.9–4.4%, depending on the racial and ethnic makeup and socioeconomics of the household (NIH, 2023). During the first 2 years of life, iron needs are high to build iron stores and support the child’s rapid physical and cognitive development rate. Premature infants, infants born to those with iron-deficiency, and infants with low birth weight have been shown to have lifelong learning and memory deficits because of damage to the hippocampus, the brain’s memory center. Accordingly, clinical consequences of ID and IDA in children include (Benson et al., 2022; Drakesmith et al., 2021):

  • Impaired psychomotor development and cognitive function
  • Delayed attention skills
  • Social withdrawal
  • Decreased leukocyte and lymphocyte function
  • Decreased response to childhood vaccines
  • Increased neurotoxicity when ID is associated with high lead blood concentrations

Infant iron stores start to diminish at 6 months of age. After this time, breastfed infants are at greater risk for anemia because the iron content of breast milk depends on the lactating person’s diet, whereas infant formula is fortified with iron. Full-term infants are at the highest risk between ages 6 months and 9 months if they are not consuming iron-fortified formula or successfully introduced to solid foods rich in iron (NIH, 2023). Additionally, children younger than 2 years are more likely than older children to have IDA associated with a transition to solid foods. Recommendations for preventing and treating ID and IDA are shown in Table 10.2.

Recommending Organization Infant Considerations Iron Dosing Iron-Fortified Foods
Centers for Disease Control and Prevention Less than 12 months old, not exclusively breastfed Iron-fortified formula Label will indicate “with iron”
Less than 12 months old, preterm or small for gestational age, exclusively breastfed 2–4 mg/kg/day elemental iron until 12 months old  
Less than 12 months old, full-term, and appropriate for gestational age, exclusively breastfed Consult health care provider for recommendations.

*If eating iron-fortified foods starting at 6 months old, iron supplement may be discontinued.
  • Infant rice cereal
  • Commercially prepared baby food: beef, turkey, pork, lamb, spinach
  • Mashed chickpeas, white beans, broccoli
  • Pureed or mashed sweet potatoes; soft, cooked beans; green peas
American Academy of Pediatrics 4–12 months old, full-term, exclusively breastfed 1 mg/kg/day elemental iron until eating iron-fortified solid foods  
1–12 months old, preterm, exclusively breastfed 2 mg/kg/day elemental iron until 12 months old  
World Health Organization 6–23 months old if diet does not include iron-fortified foods, or if living in a region where anemia prevalence is greater than 40% 2 mg/kg/day elemental iron until 24 months old  
Table 10.2 Recommendations for Iron Supplementation in Infants

Individuals living at high altitudes (greater than 1,500 m) are at increased risk for anemia secondary to increased erythropoiesis. This is a compensatory response to a lower oxygen saturation of the blood, so health care professionals must interpret hemoglobin carefully by using altitude-adjusted algorithms (Mairbäurl et al., 2023). Children living at high altitudes may need a greater intake of iron and micronutrients to avoid growth and development delays (Sharma et al., 2019).

Bleeding Risks

Vitamin K is an essential fat-soluble vitamin required for adequate blood clotting. Infants have minimal vitamin K stored at birth because only small amounts pass through the placenta. Vitamin K comes from one of two sources: diet or synthesis by anaerobic (relating to absence of oxygen) bacteria located in the stomach (Yan et al., 2022). A newborn with a healthy gut will not have bacteria-producing vitamin K until approximately 1 week of life. In addition, breast milk contains low quantities of vitamin K. All infants are therefore at high risk for vitamin K deficiency bleeding (VKDB) until they start eating solid foods, which usually occurs at age 4–6 months (Araki & Shirahata, 2020). VKDB is a condition associated with uncontrolled bleeding due to lack of sufficient vitamin K to form blood clots.

To prevent VKDB, the American Academy of Pediatrics (2022) recommends intramuscular (IM) vitamin K prophylaxis as follows:

  • Infant birth weight greater than 1500 g: 1 mg vitamin K IM within 6 hours of birth
  • Infant birth weight less than 1500 g: 0.3–0.5 mg/kg IM within 6 hours of birth

This risk for VKDB is increased for the following infants:

  • Premature infants
  • Infants who did not receive vitamin K replacement shortly after birth
  • Infants born to mothers with malabsorption or use of antiseizure drugs, antibiotics, warfarin, or antitubercular medications
  • Infants with malabsorption, cholestasis (slowing or halt of bile flow from the liver), or liver disease

Table 10.3 outlines the three types of VKDB according to the time of presentation. Early and classic VKDB occur in 1 in 60 to 1 in 250 newborns whereas late VKDB occurs in 1 in 14,000 to 1 in 25,000 infants. Newborns who do not receive a vitamin K injection are 81 times more likely to develop late VKDB (Hand et al., 2022).

Type Timing Associated Factors
Early Within 24 hours after birth
  • Maternal malabsorption or maternal use of specific medications
  • A spectrum of symptoms from simple bruising to life-threatening cranial hemorrhage
Classic Within 1 week after birth
  • No prophylaxis was received or poorly feeding
  • Exclusively breastfed
Late Between 2 weeks and 6 months after birth
  • Peaks 2–8 weeks after birth
  • No prophylaxis was received and infant exclusively breastfed
  • Infant malabsorption or cholestasis
  • Most life-threatening: cranial hemorrhage in 30–60%
Table 10.3 Types of Vitamin K Deficiency Bleeding (sources: Araki & Shirahata, 2020; CDC, 2023b)


A variety of nutritional inadequacies exist among school-aged children (aged 5–12 years), ranging from overeating (caloric excess) to undereating, often due to food insecurity. Children who overeat or undereat are at risk for hematologic consequences from nutritional deficiencies. Iron deficiency is the most common micronutrient deficiency in school-aged children, although this age group has the lowest prevalence overall among all children. Anemia in school-aged children is highest among non-Hispanic Black children, and iron deficiency is explicitly highest among Mexican American children. The etiology of deficiency is mostly diet related, apart from children with malabsorption conditions (Jefferds et al., 2022).

Iron plays an essential role in brain metabolism and neurotransmitter function, and deficiencies can lead to cognitive dysfunction (Pivina et al., 2019). School-aged children are undergoing steady linear growth and a high amount of cognitive processing. Iron deficiency with or without anemia can cause decreased school performance due to poor attention span, poor memory, and visual and auditory deficits, compromising “socioemotional development” (Rodríguez-Mañas et al., 2023). Children participating in extracurricular activities may have low energy, negatively impacting their physical performance. Signs and symptoms related to IDA often have a gradual onset in school-aged children and may not be easily detected. Research has shown a positive link between children with attention-deficit hyperactivity disorder (ADHD) and IDA. Therefore, children over 4 years of age demonstrating poor attention or impulsivity should be evaluated for ID (Mattiello et al., 2020). If it is detected, treatment and dietary changes are recommended to ensure intake of 3–6 mg/kg/day of elemental iron for 2–3 months.

Vitamin D Deficiency

Fat-soluble vitamin D is essential for calcium absorption, which takes place in the gastrointestinal tract. It is necessary for optimal bone growth; in addition, vitamin D modulates adaptive immunity, and deficiency is associated with an increased risk of infection (Giannini et al., 2022). The fortification of milk with vitamin D significantly decreased the prevalence of rickets, a softening and weakening of bones that can result in bone deformities. However, with fewer children playing outside and an increase in the use of sunscreen, vitamin D deficiency is once again a public health problem, affecting 15% of children aged 1–11 years (Porto & Abu-Alreesh, 2022). Children at increased risk for vitamin D deficiency include those with:

  • Decreased dietary intake of vitamin D
  • Dark skin tones
  • Excess weight
  • Decreased sun exposure
  • Malabsorption diseases, including celiac disease, cystic fibrosis, pancreatic insufficiency, and short bowel syndrome

The AAP recommends that all infants younger than 12 months old receive 400 units of supplemental vitamin D daily and that children older than 12 months old receive 600 units daily (Porto & Abu-Alreesh, 2022). Children with risks for deficiency or known deficiency will need higher doses.

Zinc Deficiency

Zinc is a mineral that is essential for growth in children. Deficiencies can impact hematopoiesis, resulting in poor immunity and poor wound healing. Zinc deficiency affects approximately 31% of toddlers 1–3 years old in the United States and up to 80% globally, usually due to poor diet or situations of food insecurity (Vreugdenhil et al., 2021). Zinc is naturally found in meats, poultry, fish, dairy, eggs, and dry legumes, and in the United States, grains and infant cereals are fortified with zinc. Strict vegetarians are at high risk for zinc deficiency because the body does not readily absorb the zinc found in fruits, vegetables, and bread.


Adolescence is the second time in childhood when rapid growth and development occur. Physically, socially, and psychologically, the energy and micronutrient demands are high. However, parental influence on food choices diminishes during this time, often leading to nutritional deficiencies, most commonly iron.

Adolescence is a time of increased iron needs because of the expansion of blood volume and increase in muscle mass. There are sex differences in ID without anemia in adolescents: 9–20% in females but less than 1% in males. The prevalence of IDA in adolescent females who are not menstruating is 3% (Mattiello et al., 2020). Young females are at particular risk for developing iron deficiency because of menstruation. Approximately 7% of menstruating adolescents have IDA, and those who experience menorrhagia (heavy menstrual bleeding) are at increased risk (Eiduson et al., 2021; Mattiello, 2020). It is difficult to quantify heavy menstrual bleeding outside of clinical trials; however, excessive menstrual blood loss that affects quality of life requires further evaluation and treatment (Mansour et al., 2021). Counting how often sanitary pads or tampons are changed can aid in estimating the amount of blood loss; for example, changing sanitary pads or tampons every 1–2 hours is consistent with heavy menstrual bleeding (Fulton, 2022). Common signs and symptoms of ID and IDA in adolescents include:

  • Decreased psychomotor skills
  • Poor concentration
  • Decreased academic performance
  • Shortness of breath
  • Rapid heart rate
  • Headaches
  • Dizziness and fainting
  • Restless leg syndrome
  • Irritability
  • Mild weakness
  • Fatigue and the need to nap more frequently

Oral iron replacement is recommended as the first step for treating ID and IDA in adolescents, at a dosage of 3–6 mg/kg of elemental iron daily for 2–3 months (Miniero et al., 2019). Adolescents will also need counseling regarding dietary modifications and ways to manage potential adverse effects of iron replacement. Long-term dietary changes will be necessary for female adolescents with ID or IDA associated with menstruation. For therapy to be successful, dietary modifications should reflect individual preferences. Vegetarian options may include legumes, beans, tofu, rolled oats, and quinoa.

Unfolding Case Study

Part A

Read the following clinical scenario and then answer the questions that follow. This case study will evolve throughout the chapter.

The nurse prepares to assess Catalina for more details about her past medical history and current health concerns. Catalina reports that prior to the past few months, she had felt great and had managed her grades and social life well. She does not take any medications regularly, including daily vitamins. Her mother confirms that she has no significant past medical issues, which makes her current symptoms more concerning. Catalina never complains and has always prioritized her grades. Catalina and her mother confirm that nothing has changed in their social circumstances, and Catalina denies symptoms of depression.

The nurse is aware that adolescent females are at risk for anemia and ID once menstruation begins and therefore takes a detailed menstrual bleeding history. Catalina reports that she has had regular menstrual cycles lasting 5–7 days since age 13 years but has noticed an increase in the heaviness of her flow this school year. She further says that her use of sanitary pads has increased, and she must change her pad every 1–2 hours during the day and night. The nurse recognizes this as a sign of heavy menstrual bleeding and notifies the health care provider of her concern that Catalina may be anemic and iron deficient.

What is an expected dose of oral iron supplement for Catalina?
  1. 3 mg/kg/dose twice daily for 3 months
  2. 6 mg/kg/dose twice daily for 3 months
  3. 3–6 mg/kg/day for 6 months
  4. 3 mg/kg/day until anemia is resolved
Which of the following strategies would be most effective when providing diet instruction to Catalina?
  1. Ask her to identify her food likes and dislikes.
  2. List the foods she must eat each week.
  3. Explain that she needs to make these changes on just a short-term basis until her anemia resolves.
  4. Explain that the iron supplement has side effects that she will have to tolerate if she is prescribed that medication.

Special Considerations

The Adolescent Athlete

Adolescent athletes face unique challenges related to nutritional needs. They are already at risk for nutritional deficiencies because of rapid growth, unhealthy food choices, and high-risk behaviors. Adolescent athletes have a high nutritional demand due to the daily energy expenditure associated with training and having less time to make healthy food choices. Additionally, many athletes strive for a lean body composition for a competitive edge, setting them up for disordered eating patterns that can have lifelong effects on their overall health (Kontele & Vassilakou, 2021). Adolescent athletes who limit their intake of meat products are at even higher risk for iron imbalance. Because of increased iron needs combined with potentially low iron intake and increased blood loss from menstruation, ID and IDA are common problems among adolescent female athletes and can affect their physical endurance and cognitive performance. In males, ID is often associated with higher physiologic needs from excessive training rather than from diet alone (Desbrow, 2021).

Iron deficiency can manifest as extreme fatigue, increased susceptibility to infection, impaired skeletal muscle function, and poor decision-making (Berg, 2019). Assessment for ID and IDA should be considered for both male and female athletes demonstrating these symptoms. Athletes at the highest risk for iron deficiency include those who are female; are underweight or undernourished; are vegetarian or consume limited amounts of iron-rich foods; have underlying malabsorption conditions; or compete in endurance sports.


As in other age groups, ID and IDA remain the highest cause of anemia in young and middle adults, although other nutrient deficiencies such as folate and vitamin B12 contribute (NIH, 2023). In adults ages 19–50, males require more zinc and vitamins C, K, and B complex, and menstruating females of the same age require more iron. Females are twice as likely as males to have nutritional anemia, and moderate to severe anemia is five times more common in nonpregnant females than in males. Race differences are prevalent, with the highest incidence in non-Hispanic Black adults, followed by Hispanic and White individuals (Malek, 2019; Physicians Committee for Responsible Medicine, 2020a; Rodríguez-Mañas et al., 2023).

Modern health care relies on healthy adults to maintain the blood supply. However, 25–35% of frequent blood donors will develop ID, which may not be detected if it is present without anemia (NIH, 2023). This raises concern for the frequent blood donor’s health and the quality of blood they donate (Hod et al., 2022).

Folic acid, vitamin B12, and vitamin K deficiencies in adults can also be secondary to chronic liver disease and excessive alcohol intake. Middle adults in the United States consume less than the recommended daily requirements for most essential micronutrients, leading to deficiencies that increase the risk for certain chronic conditions. Chronic diseases are now increasingly common among young adults, often because of poor nutrition, lack of physical activity, and smoking (Rodríguez-Mañas et al., 2023). Sixty percent of adults with chronic heart failure have ID, and 17% of those have IDA. The etiology of this is multifactorial and may be related to:

  • Poor nutrition
  • Malabsorption
  • Defective mobilization of iron stores
  • Cardiac cachexia (unintentional severe weight loss caused by heart failure)
  • Use of aspirin or other anticoagulant medications that can lead to microscopic blood loss in the gastrointestinal tract

The economic burden on adults with IDA includes reduced physical productivity and work capacity due to associated symptoms such as fatigue, weakness, and shortness of breath (Jefferds et al., 2022).

Later Adulthood

Aging naturally impacts physical changes, even in the healthiest adults, but healthy aging depends on proper nutrition (Kaur et al., 2019). Although energy needs decrease with age, specific micronutrient needs increase. As they age, adults become susceptible to nutrient-deficient blood abnormalities secondary to a decreased production of hormones and red blood cells, as well as decreased appetite and food intake related to delayed gastric emptying and declining oral health. In addition, older clients may experience nutritional challenges due to age- or disease-related conditions associated with chewing, swallowing, digestion, and absorption of nutrients (Physicians Committee for Responsible Medicine, 2020a). Malnutrition in this phase of life can result in lower physical function, poor quality of life, a greater risk for loss of muscle mass, and a shorter lifespan (Kaur et al., 2019; Rodríguez-Mañas et al., 2023).

Zinc deficiency occurs in approximately 60% of adults older than 70 years, leading to an increased risk for infection. Decreased dietary zinc intake and the physiologic decline in gastrointestinal absorption are the most likely reasons for this deficiency (Kaur et al., 2019).

Iron Deficiency

Older adults have the greatest incidence of nutritional anemia overall, with those aged 80–85 years having the highest. This is the only age group in which males have a greater incidence of anemia than females—as much as two times more. Older adults with anemia have increased hospitalization rates and mortality. Approximately 25–30% of older adults with congestive heart failure have anemia, worsening functional capacity, and are at increased risk of death (Ambrosy et al., 2019). With advancing age, iron stores diminish. This, along with decreased dietary intake of iron-rich foods and increased incidence of gastrointestinal malabsorption and occult blood loss, contributes to ID and IDA in older adults (Burton et al., 2020; Kaur et al., 2019). The prevalence of IDA in older adults is detailed in Table 10.4.

Age Male Female
65–75 years 11% 10.2%
76–85 years 15% 7–12%
Older than 85 years 30% 17%
Table 10.4 Prevalence of Iron Deficiency Anemia in Older Adults (Kaur et al., 2019)

Signs and symptoms of IDA in older adults may include:

  • Depression
  • Fatigue
  • Loss of muscle strength
  • Decreased cognitive function

Iron-rich foods, such as fortified grains and cereals, and oral replacement are the first step once a deficiency is confirmed; however, parenteral iron replacement may be required due to the frequency of gastrointestinal malabsorption in this population (Burton et al., 2020).

Folate and Vitamin B Deficiencies

Vitamin B12 and folate deficiencies among older adults remain a significant challenge. Approximately 10–30% of older adults are affected by atrophic gastritis, which can interfere with the absorption of vitamin B12 and folate (NIH, 2022). Additionally, the metabolic processes of each micronutrient are interconnected, so it is difficult to distinguish the source of physical manifestations (Socha et al., 2020). Signs and symptoms include:

  • Risk for cardiovascular disease
  • Cognitive impairment
  • Insomnia
  • Impaired mood
  • Decreased decision-making ability
  • Decreased physical performance, leading to increased risk for falls and fractures

Folate deficiency is more likely to be related to decreased absorption and reduced dietary intake, whereas vitamin B12 deficiency is more often associated with diseases of malabsorption and polypharmacy. Mild vitamin B12 deficiency occurs in 20% of adults older than 60, and severe deficiency occurs in 6% of adults older than 70 (NIH, 2022). Nonhematologic symptoms range from vague and nonspecific to severe neurologic and neuropsychiatric disorders (Stauder et al., 2018). Folate deficiency is reported to occur in 5–20% of older adults and is more common in those who smoke, consume excessive amounts of alcohol, are obese, or live alone (Rotstein et al., 2022). Vitamin B12 deficiency anemia is more likely to be associated with neurologic symptoms not seen in individuals with folate deficiency anemia (Stauder et al., 2018). Anemia associated with both of these deficiencies can be distinguished from IDA based on the size of red blood cells; iron deficiency anemia is microcytic, whereas folate and vitamin B12 deficiencies are macrocytic. Treatment is focused on nutrient replacement and diet modification.


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