Nutrition Interventions for Children with Special Health Care Needs

Chapter 21 - Nutrition Interventions for Metabolic Disorders
and include, for example, the restriction of specific amino acids or total protein,
fatty acids, simple sugars, or total carbohydrate (1,2). In general, the strategies
for treatment focus on reducing the negative impact of the affected enzyme and
normalizing biochemical status. These goals can be achieved by using one or more
dietary modification or intervention strategies, depending on the disorder:
• reduce the substrate
• provide the product(s)
• supplement co-factors
• enhance elimination of excess nitrogen
The protein and amino acid restrictions require the critical assessment of protein and
energy intakes; particular attention must be paid to the protein-energy ratio of these
prescribed diets. See Table 19-1 for nutritional restrictions and modifications for
selected metabolic disorders.
The nutrient needs of each individual must be carefully considered and the
dietary prescription based on the individual genetic and biochemical requirements
for nutrients. If the specific nutrient needs of an individual are ignored or
misunderstood, mental retardation, metabolic crisis, growth failure, neurologic crisis,
organ damage, or death may occur.
For many metabolic disorders, especially those involving amino acid metabolism,
it is extremely difficult to correct the metabolic imbalances caused by the disorder
and meet the nutritional requirements for growth, maintenance, and activity without
the use of a specialized semi-synthetic formula or medical food. The formulas are
generally supplemented with small amounts of high biological value (HBV) protein to
supply the restricted amino acid(s) to the requirement level. These formulas provide
75-80% of the total protein intake for the individual. Nitrogen-free foods are often
needed to provide an appropriate energy intake, such as low protein pasta, bread,
and other baked goods (4,5,6).
Maintaining metabolic balance for these children requires frequent and intensive
monitoring of biochemical parameters specific to the disorder and those indicative
of normal nutritional status. The goal is to achieve biochemical levels at or near the
normal range. Laboratory parameters that are frequently monitored include:
• plasma amino acids
• hematological status
• protein status
• electrolytes
• blood lipid level
• ammonia
238 Nutrition Interventions for Children With Special Health Care Needs