Vitamin Imbalances

Although true vitamin deficiencies are rare in the United States, subclinical deficiencies are commonly seen in population subgroups in which either maternal or child dietary intake is imbalanced and contains inadequate amounts of vitamins. Vitamin D–deficiency rickets, once rarely seen because of the widespread commercial availability of vitamin D–fortified milk, increased before the turn of the century. Populations at risk include the following:

The American Academy of Pediatrics (AAP) (2008) recommends that infants who are breastfed exclusively receive 400 IU of vitamin D beginning shortly after birth to prevent rickets and vitamin D deficiency. Vitamin D supplementation should continue until the infant is consuming at least 1 L/day (or 1 quart/day) of vitamin D–fortified formula (AAP, 2008). Nonbreastfed infants who are taking less than 1 L/day of vitamin D–fortified formula should also receive a daily vitamin D supplement of 400 IU. Inadequate maternal ingestion of cobalamin (vitamin B₁₂) may contribute to infant neurologic impairment when exclusive breastfeeding (past 6 months) is the only source of the infant’s nutrition. A correlation between the incidence of childhood upper respiratory infections and vitamin D deficiency has been found, but the implications of the findings have yet to be completely understood (Taylor and Camargo, 2011; Walker and Modlin, 2009).

Children may also be at risk for vitamin deficiencies secondary to disorders or their treatment. For example, vitamin deficiencies of the fat-soluble vitamins A and D may occur in malabsorptive disorders such as cystic fibrosis and short bowel syndrome. Preterm infants may develop rickets in the second month of life as a result of inadequate intake of vitamin D, calcium, and phosphorus. Children receiving high doses of salicylates may have impaired vitamin C storage. Environmental tobacco smoke exposure has been implicated in decreased concentrations of ascorbate in children; therefore increased intake of sources of vitamin C should be encouraged even in children minimally exposed to environmental tobacco smoke (Preston, Rodriguez, and Rivera, 2003). Children with chronic illnesses resulting in anorexia, decreased food intake, or possible nutrient malabsorption as a result of multiple medications should be evaluated carefully for adequate vitamin and mineral intake in some form (parenteral or enteral).

Children with sickle cell disease are reported to have suboptimal intakes (according to DRI recommendations) of vitamins E and D, folate, calcium, and fiber, which decrease significantly with increasing age. Poor dietary intake was a significant factor in the findings of the study (Kawchak, Schall, Zemel, et al., 2007). One study found that children with intestinal failure who were being transitioned from parenteral to enteral nutrition had at least one vitamin and mineral deficiency; vitamin D was the most common deficiency identified, and zinc and iron were the most common minerals identified as being deficient (Yang, Duro, Zurakowski, et al., 2011).

Vitamin A deficiency has been reported with increased morbidity and mortality in children with measles. However, a Cochrane review of studies wherein a single dose of vitamin A was administered to children with measles found no decrease in mortality. Children with measles younger than the age of 2 years who received two doses of vitamin A (200,000 IU) on consecutive days did have decreased mortality rates and a reduced rate of pneumonia-specific mortality (Huiming, Chaomin, and Meng, 2005). Complications from diarrhea and infections are often increased in infants and children with vitamin A deficiency. Although scurvy (caused by a deficiency of vitamin C) is rare in developed countries, cases have been reported in children who were fed an organic diet deficient in vegetables and fruits (Burk and Molodow, 2007).

An excessive dose of a vitamin is generally defined as 10 or more times the Recommended Dietary Allowance (RDA), although the fat-soluble vitamins, especially vitamins A and D, tend to cause toxic reactions at lower doses. With the addition of vitamins to commercially prepared foods, the potential for hypervitaminosis has increased, especially when combined with the excessive use of vitamin supplements. Hypervitaminosis of vitamins A and D presents the greatest problems because these fat-soluble vitamins are stored in the body. High intakes of vitamin A have been linked to physeal growth arrest, which can lead to osteoporosis, fracture, and metaphyseal irregularity (Saltzman and King, 2007). Chronic hypervitaminosis A may result in signs and symptoms of headache; vomiting; dry, itching desquamating skin; anorexia; fissures at the corner of the mouth; weight loss; bulging fontanels; and neurologic signs such as irritability and stupor (Zile, 2011). An excessive intake of vitamin A in pregnant women has also been linked to fetal defects (Zile, 2011). Vitamin D is the most likely of all vitamins to cause toxic reactions in relatively small overdoses. The water-soluble vitamins, primarily niacin, B₆, and C, can also cause toxicity. Poor outcomes in infants (e.g., fatal hypermagnesemia) have been associated with megavitamin therapy with high doses of magnesium oxide, and severe anemia and thrombocytopenia have resulted from megadoses of vitamin A.

One vitamin supplement that is recommended for all women of childbearing age is a daily dose of 0.4 mg of folic acid, the usual RDA. Folic acid taken before conception and during early pregnancy can reduce the risk of neural tube defects such as spina bifida by as much as 70%. Drugs such as oral contraceptives and antidepressants may decrease folic acid absorption; thus adolescent girls taking such medications should consider supplementation. (See Spina Bifida (Myelomeningocele, Chapter 49.)

Mineral Imbalances

A number of minerals are essential nutrients. The macrominerals refer to those with daily requirements greater than 100 mg and include calcium, phosphorus, magnesium, sodium, potassium, chloride, and sulfur. Microminerals, or trace elements, have daily requirements of less than 100 mg and include several essential minerals and those in which the exact role in nutrition is still unclear. The greatest concern with minerals is deficiency, especially iron deficiency anemia (see Chapter 43). However, other minerals that may be inadequate in children’s diets, even with supplementation, include calcium, phosphorus, magnesium, and zinc. Low levels of zinc can cause nutritional growth failure (failure to thrive [FTT]). Some of the macrominerals may be overlooked inadvertently when a child with intestinal failure or recent surgery is making the transition from total parenteral to enteral intake.

An imbalance in the intake of calcium and phosphorous may occur in infants who are given whole cow’s milk instead of infant formula; neonatal tetany may be observed in such cases. Whole cow’s milk is also a poor source of iron, and inadequate intake of iron from other food sources such as iron-fortified cereal may cause iron deficiency anemia.

The regulation of mineral balance in the body is a complex process. Dietary extremes of mineral intake can cause a number of mineral-mineral interactions that could result in unexpected deficiencies or excesses. For example, excessive amounts of one mineral such as zinc can result in a deficiency of another mineral such as copper even if sufficient amounts of copper are ingested. Thus megadose intake of one mineral may cause an inadvertent deficiency of another essential mineral by blocking its absorption in the blood or intestinal wall or competing with binding sites on protein carriers needed for metabolism.

Deficiencies can also occur when various substances in the diet interact with minerals. For example, iron, zinc, and calcium can form insoluble complexes with phytates or oxalates (substances found in plant proteins), which impair the bioavailability of the mineral. This type of interaction is important in vegetarian diets because plant foods such as soy are high in phytates. Contrary to popular opinion, spinach is not an ideal source of iron or calcium because of its high oxalate content. Factors that affect iron absorption are listed in Chapter 32.

Children with certain illnesses are at greater risk for growth failure, especially in relation to bone mineral deficiency as a result of the treatment of the disease, decreased nutrient intake, or decreased absorption of necessary minerals. Those at risk for such deficiencies include children who are receiving or have received radiation and chemotherapy for cancer; children with human immunodeficiency virus (HIV), sickle cell disease, cystic fibrosis, gastrointestinal (GI) malabsorption, or nephrosis; and extremely low–birth-weight (ELBW) and very low–birth-weight (VLBW) preterm infants.

Protein-Energy Malnutrition (Severe Childhood Undernutrition)

Malnutrition continues to be a major health problem in the world today, particularly in children younger than 5 years of age. However, lack of food is not always the primary cause of malnutrition. In many developing and underdeveloped nations, diarrhea (gastroenteritis) is a major factor. Additional factors are bottle-feeding (in poor sanitary conditions), inadequate knowledge of proper child care practices, parental illiteracy, economic and political factors, climate conditions, cultural and religious food preferences, and simply a lack of adequate food. Müller and Krawinkel (2005) point out that poverty is the underlying cause of malnutrition. The most extreme forms, or protein-energy malnutrition (PEM), are kwashiorkor and marasmus. Some authorities suggest that severe malnutrition encompasses more than protein-energy deficits and thus prefer the term severe childhood undernutrition (SCU). Another term used is severe acute malnutrition (SAM). Entities such as the WHO continue to use the term protein-energy malnutrition. SCU may also be subdivided into edematous (kwashiorkor) and nonedematous (marasmus) types.

In the United States milder forms of PEM are seen as a result of primary malnutrition, although the classic cases of marasmus and kwashiorkor may also occur. Unlike in developing countries, where the main reason for PEM is inadequate food, in the United States PEM occurs despite ample dietary supplies (see Failure to Thrive, Chapter 31). It may also be seen in people with chronic health problems such as cystic fibrosis, renal dialysis, cancer, and GI malabsorption; in elderly adults who have chronic malnutrition; and in people with acute illnesses such as prolonged, untreated anorexia nervosa. Kwashiorkor has been reported in the United States in children fed only a rice beverage diet (Rice Dream) and few solid foods and in infants who were fed nonstandard infant diets such as flour water, corn porridge, molasses, and nondairy creamer (Katz, Mahlberg, Honig, et al., 2005; Tierney, Sage, and Shwayder, 2010). Kwashiorkor has also been reported in the United States when infants have been fed inappropriate food as a result of parental (caretaker) nutritional ignorance, a perceived cow’s milk–based formula intolerance, family social chaos, or cow’s milk intolerance. Therefore it is important that health care workers not assume that PEM cannot occur in developed countries; a comprehensive dietary history should be obtained in any child with clinical features resembling PEM.

Food Allergy

In late 2010 the National Institute of Allergy and Infectious Diseases (NIAID), working with 34 other professional organizations, published new evidence-based guidelines for the diagnosis and management of food allergy. A food allergy is defined by the NIAID as “an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food” (Boyce, Assa’ad, Burks, et al., 2010, p. 1108). Food allergens are defined as specific components of food or ingredients in food such as a protein that are recognized by allergen-specific immune cells eliciting an immune reaction that results in the characteristic symptoms (Boyce, Assa’ad, Burks, et al., 2010). A food intolerance is said to exist when a food or food component elicits a reproducible adverse reaction but does not have an established or likely immunologic mechanism (Boyce, Assa’ad, Burks, et al., 2010). The example given suggests that a person may have an immune-mediated allergy to cow’s milk protein, but the person who is unable to digest the lactose in cow’s milk is considered to be intolerant, not allergic, to it. The NIAID guidelines classify food allergy according to the following: food-induced anaphylaxis, GI food allergies, and specific syndromes; cutaneous reactions to foods; respiratory manifestation; and Heiner syndrome (Boyce, Assa’ad, Burks, et al., 2010). The exact prevalence of food allergies in children is reported to be much lower than that which parents report. Approximately 6% of children may experience food allergic reactions in the first 2 to 3 years of life; 1.5% will have an allergy to eggs, 2.5% to cow’s milk, and 1% to peanuts (Sampson and Leung, 2011). Seafood allergies in children are reported to be low in the United States: 0.2% for fish and 0.5% for crustaceans (Boyce, Assa’ad, Burks, et al., 2010). Diagnosed allergy to milk and eggs was found to be 2.2% in a Danish study and 1.6% in a Norwegian study. The NIAID report further points out that most children will eventually be able to tolerate milk, eggs, soy, and wheat; far fewer will ever tolerate tree nut and peanuts (Boyce, Assa’ad, Burks, et al., 2010). The NIAID report indicates that 50% to 90% of all presumed food allergies are not actually allergies. The NIAID’s (Boyce, Assa’ad, Burks, et al., 2010) guidelines also recommend the following:

A summary of the NIAID guidelines is provided by McBride (2011).

The clinical manifestations of food allergy may be divided as follows (AAP, 2009):

Food allergies usually occur either as an immunoglobulin E (IgE)–mediated or non–IgE-mediated immune response; some toxic reactions may occur as a result of a toxin found within the food. Food allergy is caused by exposure to allergens, usually proteins (but not the smaller amino acids), that are capable of inducing IgE antibody formation (sensitization) when ingested. Sensitization refers to the initial exposure of an individual to an allergen, resulting in an immune response; subsequent exposure induces a much stronger response that is clinically apparent. Consequently food allergy typically occurs after the food has been ingested one or more times. The NIAID report (Boyce, Assa’ad, Burks, et al., 2010) indicates that sensitization alone is not sufficient to classify as a food allergy; rather an immune-mediated response and manifestation of specific sign and symptoms are necessary to categorize an individual as having a food allergy. The most common food allergens are listed in Box 41-1.

Oral allergy syndrome occurs when a food allergen (commonly fruits and vegetables) is ingested and there is subsequent edema and pruritus involving the lips, tongue, palate, and throat. Recovery from symptoms is usually rapid. Immediate GI hypersensitivity is an IgE-mediated reaction to a food allergen; reactions include nausea, abdominal pain, cramping, diarrhea, vomiting, anaphylaxis, or all of these. Additional food allergies seen in young children include allergic eosinophilic esophagitis, allergic eosinophilic gastroenteritis, food protein–induced proctocolitis, and food protein–induced enterocolitis.

Food allergy or hypersensitivity may also be classified according to the interval between ingestion and the manifestation of symptoms: immediate (within minutes to hours) or delayed (2 to 48 hours) (AAP, 2009).

Food allergies can occur at any time but are common during infancy because the immature intestinal tract is more permeable to proteins than the mature intestinal tract, thus increasing the likelihood of an immune response. Allergies in general demonstrate a genetic component: children who have one parent with an allergy have a 50% or greater risk of developing one; children who have both parents with an allergy have up to a 100% risk of developing one. Allergy with a hereditary tendency is referred to as atopy. Some infants with atopy can be identified at birth from elevated levels of IgE in umbilical cord blood.

Deaths have been reported in children who experienced an anaphylactic reaction to food. Onset of the reactions occurred shortly after ingestion (5 to 30 minutes). In most of the children the reactions did not begin with skin signs such as hives, red rash, and flushing but rather mimicked an acute asthma attack (wheezing, decreased air movement in airways, dyspnea). Watch children with food anaphylaxis closely because a biphasic response has been recorded in a number of cases in which there is an immediate response, apparent recovery, and acute recurrence of symptoms (Simons, 2009) (see Nursing Alert and Emergency box). Children with extremely sensitive food allergies should wear a medical identification bracelet and have an injectable epinephrine cartridge (EpiPen) readily available. (See Anaphylaxis, Chapter 42.) Any child with a history of food allergy or previous severe reaction to food should have a written emergency treatment plan and an EpiPen. Note that Benadryl and cetirizine are effective for cutaneous and nasal manifestations but not for airway manifestations (Keet, 2011).

Although the reason is unknown, many children “outgrow” their food allergies, especially to milk and eggs. Approximately 50% of all infants who are intolerant to cow’s milk usually develop tolerance by 3 to 5 years of age (Sampson and Leung, 2011). More than half (60%) of infants have an IgE-mediated reaction to cow’s milk, and 25% retain sensitivity until the second decade of life. Children who are allergic to more than one food may develop tolerance to each food at a different time. The most common allergens such as peanuts are outgrown less readily than other food allergens. Because of the tendency to lose the hypersensitivity, allergenic foods should be reintroduced into the diet after a period of abstinence (usually ≥1 year) to evaluate whether the food can safely be added to the diet. However, foods that are associated with severe anaphylactic reactions continue to present a lifelong risk and must be avoided.

Lactose Intolerance

Lactose intolerance refers to at least four different entities that involve a deficiency of the enzyme lactase, which is needed for the hydrolysis or digestion of lactose in the small intestine; lactose is hydrolyzed into glucose and galactose. Congenital lactase deficiency occurs soon after birth after the newborn has consumed lactose-containing milk (human milk or commercial formula). This inborn error of metabolism involves the complete absence or severely reduced presence of lactase, is extremely rare, and requires a lifelong lactose-free or extremely reduced lactose diet.

Primary lactase deficiency, sometimes referred to as late-onset lactase deficiency, is the most common type of lactose intolerance and is manifested usually after 4 or 5 years of age, although the time of onset is variable. Ethnic groups with a high incidence of lactase deficiency include Asians, southern Europeans, Arabs, Israelis, and African-Americans; Scandinavians tend to have the lowest incidence. Lactose malabsorption manifests as lactose intolerance and is characterized by an imbalance between the ability for lactase to hydrolyze the ingested lactose and the amount of lactose ingested (Heyman and AAP Committee on Nutrition, 2006).

Secondary lactase deficiency may occur secondary to damage of the intestinal lumen, which decreases or destroys the enzyme lactase. Cystic fibrosis; sprue; celiac disease; kwashiorkor; and infections such as giardiasis, HIV, or rotavirus may cause a temporary or permanent lactose intolerance.

Developmental lactase deficiency refers to the relative lactase deficiency observed in preterm infants of less than 34 weeks of gestation (Heyman and AAP Committee on Nutrition, 2006).

The primary symptoms of lactose intolerance include abdominal pain, bloating, flatulence, and diarrhea after the ingestion of lactose. The onset of symptoms occurs within 30 minutes to several hours of lactose consumption. Lactose intolerance is often perceived as an allergy; and, in several studies with reports of acute GI symptoms ascribed to lactose intolerance, measurement of lactase activity is normal.

Lactose intolerance may be diagnosed on the basis of the history and improvement with a lactose-reduced diet. The breath hydrogen test is used to positively diagnose the condition. Breath samples in lactose-deficient individuals yield a higher percentage of hydrogen (≥20 parts per million [ppm] above baseline). In infants lactose malabsorption may be diagnosed by evaluating fecal pH and reducing substances; fecal pH in infants is usually lower than in older children, but an acidic pH may indicate malabsorption (Heyman and AAP Committee on Pediatrics, 2006).

Treatment of lactose intolerance is elimination of offending dairy products; however, some advocate decreasing amounts of dairy products rather than total elimination, especially in small children (Heyman and AAP Committee on Nutrition, 2006). In infants lactose-free or low-lactose formula offers no special advantages over lactose-containing formula except in those who are severely malnourished (Heyman and AAP Committee on Pediatrics, 2006).

One concern is that dairy avoidance in children and adolescents with lactose intolerance contributes to reduced bone mineral density and osteoporosis (AAP, 2009; Suchy, Brannon, Carpenter, et al., 2010). Evidence indicates that dietary lactose enhances calcium absorption and that lactose-free diets may negatively affect bone mineralization (Heyman and AAP Committee on Nutrition, 2006). It is recommended that individuals with lactose maldigestion who do not experience lactose intolerance symptoms continue to consume small amounts of dairy products with meals to prevent reduced bone mass density and subsequent osteoporosis. Some evidence indicates that probiotics (food preparations containing microorganisms such as Lactobacillus, which alter the GI microflora and thus are beneficial to the host) improve lactose intolerance when live cultures are fermented in dairy products (de Vrese and Schrezenmeir, 2008). The positive attributes of probiotics for those with lactose maldigestion include delayed GI transit (slower than milk), positive effects on intestinal and colonic microflora, and a reduction of maldigestion symptoms.

Most people are able to tolerate small amounts of lactose (≈1 cup of milk per day) even in the presence of deficient lactase activity (Heyman and AAP Committee on Nutrition, 2006; Suchy, Brannon, Carpenter, et al., 2010) and should be encouraged to continue their intake of dairy products in small amounts to obtain much-needed nutrients. Milk taken at meals may be better tolerated than when taken alone (see Family-Centered Care box). Pretreated milk (with microbial-derived lactase) is reported to be effective in improving lactose absorption. Because dairy products are a major source of calcium and vitamin D, supplementation of these nutrients is needed to prevent deficiency. Yogurt contains inactive lactase enzyme, which is activated by the temperature and pH of the duodenum; this lactase activity substitutes for the lack of endogenous lactase. Fresh, plain yogurt may be tolerated better than frozen or flavored yogurt; hard cheeses, lactase-treated dairy products, and lactase tablets taken with dairy products are also viable options. An important distinction between lactose intolerance and food allergy is that lactose intolerance does not manifest as an anaphylactic-type reaction.