Health Consequences Of Vitamin Deficiencies In Children

As early as the 1500s, people recognized that excluding certain foods from their diets led to disease. For example, British sailors developed scurvy on a diet that was devoid of fruits and vegetables. In 1911, the first vitamin, thiamin, was isolated from rice polishings following investigations into the causes of beriberi among Japanese sailors. In the past century, our knowledge of vitamins -- and the diseases that occur when we don't get them -- has expanded dramatically. We have also learned that vitamin deficiencies can be particularly devastating in growing children.

Vitamin A Deficiency

According to the World Health Organization, vitamin A deficiency is the world's leading cause of preventable childhood blindness. Xerophthalmia, a condition characterized by dry eyes and thickening of the corneas, is almost diagnostic of vitamin A deficiency. The skin and mucous membranes also become thickened and dry, and growth retardation is common. Night blindness may be an early sign of vitamin A deficiency in older children. Immune function is typically impaired, leading to frequent respiratory and gastrointestinal infections, which may be fatal.

Vitamin D Deficiency

The Merck Manual of Diagnosis and Therapy states that vitamin D deficiency can result from inadequate intake, reduced intestinal absorption, abnormal metabolism or cellular resistance to the vitamin's effects. A lack of sunlight exposure is probably a contributing cause in older children.

A 2006 study in "Breastfeeding Medicine" demonstrated that nursing mothers who consumed the recommended daily intake of vitamin D supplied extremely small amounts to their infants, signifying a possible shortcoming in current guidelines. Muscle aches, weakness and bone pain are common signs of vitamin D deficiency at any age. In infants, deficiency can cause softening of the skull and delayed sitting and crawling, while older children develop the classic signs of rickets: wrist and ankle enlargement, scoliosis, delayed walking and bowlegs or knock-knees. Severe deficiency can also cause progressively severe neurologic symptoms, including numbness of the lips, tongue and fingertips, muscle spasms in the face, hands and feet and seizures. Vitamin D deficiency may be implicated in childhood immunologic or hormonal dysfunction as more research is completed.

Vitamin E Deficiency

The most common cause of vitamin E deficiency is inadequate intake, although some genetic and medical conditions can interfere with absorption. Signs and symptoms of deficiency in children include difficulties with walking or balance, muscle weakness, paralysis of eye muscles, speech impairment and loss of deep tendon reflexes. Anemia also occurs, but it is usually not severe.

Vitamin K Deficiency

Deficiency of vitamin K results from inadequate intake. Although intestinal bacteria synthesize some vitamin K, the amount is insufficient for a child's daily needs. Breastfed infants are at a higher risk for deficiency due to the paucity of vitamin K in breast milk. Since vitamin K is essential for producing clotting factors, a deficiency of this nutrient increases a child's risks for bleeding. Easy bruisability, frequent nosebleeds or blood in the stool or urine might signal vitamin K deficiency. In very young infants, a lack of vitamin K can contribute to bleeding in the brain, which can be fatal or cause lifelong disability.

The B Vitamins

The B vitamins often cooperate to perform their cellular functions, and they are usually found together in foods. Therefore, deficiencies of B vitamins frequently occur together. B vitamins are water-soluble, so most of them don't store well in the body.

This family of vitamins is crucial for the normal development and function of the nervous system. In fetuses, a lack of folate causes defects in brain and spinal cord development, while older children often develop diarrhea and anemia. Niacin deficiency can cause a classic illness called pellagra, which is characterized by oral ulcers, an inflamed tongue, a symmetric rash that worsens in the sun, diarrhea that is sometimes bloody and mental aberrations, such as confusion, disorientation, mania and, eventually, coma. Insufficient thiamin intake causes irritability, abdominal pain, fatigue and sleeplessness. Untreated thiamin deficiency progresses to beriberi, an illness manifested by abnormal sensations in the hands and feet, muscle cramps, muscle wasting and heart failure.

Deficiency of vitamin B6 causes dermatitis, anemia, a sore tongue and, occasionally, seizures. Vitamin B12 deficiency usually develops slowly, because the body does maintain some stores of this nutrient. For example, in non-supplemented, breastfed babies of vegan mothers, B12 deficiency often develops by age four to six months. Depending on a child's age, signs and symptoms of B12 deficiency include anemia, abdominal pain, loss of appetite, constipation and neurologic problems that include loss of balance, weakness, poor reflexes, difficulty walking, confusion and spasticity. Without treatment, B12 deficiency can cause permanent damage to the brain and spinal cord.

Vitamin C Deficiency

Vitamin C deficiency is uncommon in developed countries, but it still occurs in areas where undernutrition is common. Since this vitamin's role in preventing scurvy is well-known, severe deficiency is rare. Vitamin C participates in the formation of healthy connective tissues, so growing children who are deficient in this nutrient can exhibit poor bone growth, joint problems, poor dental development or early loss of deciduous teeth, impaired wound healing, easy bruisability and stress fractures of the bones. Irritability, lethargy and and failure to thrive are also common.

Considerations

Vitamin deficiencies are relatively uncommon in developed countries, but they can occur even in wealthy nations where segments of the population have limited access to nutritious food. Even when anti-hunger programs are instituted by governments and charitable organizations, children cannot always access them. Certain behaviors, such as avoidance of sun exposure, can contribute to specific vitamin deficiencies even when nutrition is otherwise adequate. Genetic defects that interfere with vitamin absorption or metabolism and medications that interact with a specific vitamin are less common causes of vitamin deficiencies among children.