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Information

Select Inborn Errors of Metabolism Treated With Commercially Available Medical Foods

Inborn Error of Metabolism

Modify or Restrict

Vitamin or Cofactor Responsive

Other Therapies

Phenylketonuria

Phenylalanine

<1% of cases are attributable to biopterin synthetic defect and require biopterin supplementation. Sapropterin dihydrochloride treatment lowers blood phenylalanine in an additional 20% to 40% of phenylketonuria patients. Most patients respond to pegylated recombinant phenylalanine ammonia-lyase

Supplemental tyrosine or other large neutral amino acids

Tyrosinemia type I

Phenylalanine,

tyrosine,

methionine

No

Nitisinone

Tyrosinemia type II

Phenylalanine,

tyrosine

No

Maple syrup urine disease

Leucine, valine, isoleucine

Rare cases are thiamine responsive

Optimize valine and isoleucine levels to ensure the leucine level remains in the normal range

Isovaleric acidemia

Leucine

No

Supplemental carnitine and glycine

Methylmalonic acidemia

Isoleucine, valine, methionine, threonine

Some cases are attributable to defect in cobalamin metabolism

Supplemental carnitine

Propionic acidemia

Isoleucine, valine, threonine

Supplemental carnitine

Homocystinuria

Methionine

Some cases are pyridoxine responsive

Supplemental folate, betaine (converts homocysteine to methionine)

Ornithine transcarbamylase deficiency

Protein

No

Supplemental citrulline, benzoate, phenylacetate, phenylbutyrate

Citrullinemia

Protein

No

Supplemental arginine, benzoate, phenylacetate, phenylbutyrate

Glutaric aciduria type I

Lysine, tryptophan

Possible role for riboflavin

Supplemental carnitine

Long-chain fatty acid oxidation disorders

Dietary long-chain fatty acids

Avoid fasting, supplement with medium-chain triglyceride oil or triheptanoin

From American Academy of Pediatrics. Pediatric Nutrition. 9th ed. American Academy of Pediatrics; 2025.

Therapy for Other Select Inborn Errors of Metabolism

Inborn Error of Metabolism

Modify or Restrict

Vitamin or Cofactor Responsive

Other Therapies

Biotinidase deficiency

None

Biotin

Familial hypophosphatemic rickets

None

1,25-dihydroxy-vitamin D

Phosphorus

Acrodermatitis enteropathica

None

Zinc

Pyruvate dehydrogenase deficiency

Low-carbohydrate, high-fat diet

Possibly thiamine responsive

Alkali therapy

Galactosemia (transferase deficiency)

Galactose, lactose

Lactose-free infant formula

Glycogen storage diseases

Lactose, fructose, sucrose

Frequent feedings, complex starches, high-protein diet

Fructosemia (fructose-1,6-bisphosphatase or aldolase deficiency)

Fructose

Frequent glucose feedings in bisphosphatase deficiency

Medium-chain acyl-CoA dehydrogenase deficiency

Avoid fasting, possible supplemental carnitine

Barth syndrome (X-linked 3-methyl-glutaconic aciduria)

None

Pantothenic acid

Cystinosis

None

None

Cysteamine, phosphate, potassium, vitamin D, alkali

Alpha-aminoadipic semialdehyde dehydrogenase deficiency (pyridoxine responsive epilepsy)

Pyridoxine

Cerebral folate deficiency

None

Folinic acid

Creatine synthesis disorders

None

Creatine

Thiamine-responsive megaloblastic anemia syndrome

None

Thiamine

CoA, coenzyme A.

From American Academy of Pediatrics. Pediatric Nutrition. 9th ed. American Academy of Pediatrics; 2025.