Last update Nov. 23, 2019

Infant Phenylketonuria

Very Low Risk

Safe. Compatible. Minimal risk for breastfeeding and infant.

An autosomal recessive congenital disease in which there is an enzyme deficit that prevents the metabolization of the essential amino acid phenylalanine (Phe) to the amino acid tyrosine, producing an accumulation of Phe in the body that, untreated, damages the central nervous system causing mental deficiency.
The treatment consists of restricting from one’s diet foods that contain large quantities of Phe, especially pulses, soy, meat, fish, eggs, cereals (except rice and corn), dairy products and the sweetener aspartame.
This restriction, which is fundamental in the initial stage of life, is recommended to be life-long.

Since 1980 when it was discovered that breastmilk has a low concentration of Phe (29-64 mg / dL), lower than milk formula (Lawrence 2016 p.493, Banta-Wright 2012), breastfeeding, supplemented with special formulas that are Phe-free, is now considered an indicated feeding method for infants affected by phenylketonuria (Kose 2017, Lawrence 2013, Lamônica 2012, Cornejo 2003, Duncan 1997).

There are several dietary control protocols (Duncan 1997). Plasma Phe checks should be frequent (initially weekly) and be maintained between 2 and 6 mg/dL (120-360 mmol/L) varying the amount of special formula offered in each feed before breastfeeding (Lawrence 2016 p.493, Lamônica 2012) or the daily number of breastmilk feeds "ad libitum" alternated with special formula feeds (van Rijn 2003) based on these levels.

More than half of the diet can be breastmilk (Lawrence 2016 p.493). Mothers must handle breastmilk extraction and storage techniques well.
They should not take aspartame (Lawrence 2016 p.315).
Control and monitoring must be undertaken by specialized personnel.

Weight gain was similar or greater and there is equal or more frequency of Phe plasma levels within the range in breastfed phenylketonuric infants than in non-breastfed infants (Kose 2017, Banta-Wright 2012, Kanufre 2009, Hinrichs 1994). The number of days needed for Phe levels to return to normal was similar (7-8 days on average) in both groups (Kanufre 2009, Motzfeldt 1999).

Growth (weight, height, head circumference) was monitored in 74 phenylketonuric infants breastfed for an average of 7 months, ranging from 1 to 16 months (Motzfeldt 1999).

Eight out of ten large European centres treating infants with phenylketonuria promote breastfeeding within dietary procedure (Ahring 2009).

With respect to not having been breastfed, breastfeeding prior to the diagnosis of phenylketonuria improved neurodevelopment in schoolchildren, with an average of 13 points higher in IQ (Riva 1996).

Despite all its advantages, abandonment and shorter duration of breastfeeding has been observed following the diagnosis of phenylketonuria in infants, partly due to the difficulty of measuring Phe intake (Banta-Wright 2014).

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Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Infant Phenylketonuria in other languages or writings:


Infant Phenylketonuria belongs to this group or family:


  1. MotherToBaby. Maternal PKU. Fact Sheet 2017 Full text (link to original source) Full text (in our servers)
  2. Kose E, Aksoy B, Kuyum P, Tuncer N, Arslan N, Ozturk Y. The Effects of Breastfeeding in Infants With Phenylketonuria. J Pediatr Nurs. 2017 Abstract
  3. MotherToBaby. Fenilcetonuria materna. Hoja informativa. 2015 Full text (link to original source) Full text (in our servers)
  4. Banta-Wright SA, Press N, Knafl KA, Steiner RD, Houck GM. Breastfeeding infants with phenylketonuria in the United States and Canada. Breastfeed Med. 2014 Abstract Full text (link to original source) Full text (in our servers)
  5. Lawrence RM. Circumstances when breastfeeding is contraindicated. Pediatr Clin North Am. 2013 Feb;60(1):295-318. Abstract
  6. Banta-Wright SA, Shelton KC, Lowe ND, Knafl KA, Houck GM. Breast-feeding success among infants with phenylketonuria. J Pediatr Nurs. 2012 Abstract Full text (link to original source) Full text (in our servers)
  7. Lamônica DA, Stump MV, Pedro KP, Rolim-Liporacci MC, Caldeira AC, Anastácio-Pessan Fda L, Gejão MG. Acompanhamento do aleitamento materno no tratamento de crianças com fenilcetonúria. J. Soc. Bras. Fonoaudiol. vol.24 no.4 São Paulo 2012 Full text (link to original source) Full text (in our servers)
  8. Lamônica DA, Stump MV, Pedro KP, Rolim-Liporacci MC, Caldeira AC, Anastácio-Pessan Fda L, Gejão MG. Breastfeeding follow-up in the treatment of children with phenylketonuria. J Soc Bras Fonoaudiol. 2012 Abstract Full text (link to original source) Full text (in our servers)
  9. Ahring K, Bélanger-Quintana A, Dokoupil K, Gokmen Ozel H, Lammardo AM, MacDonald A, Motzfeldt K, Nowacka M, Robert M, van Rijn M. Dietary management practices in phenylketonuria across European centres. Clin Nutr. 2009 Abstract
  10. Kanufre VC, Starling AL, Leão E, Aguiar MJ, Santos JS, Soares RD, Silveira AM. Breastfeeding in the treatment of children with phenylketonuria. J Pediatr (Rio J). 2007 Abstract Full text (link to original source) Full text (in our servers)
  11. van Rijn M, Bekhof J, Dijkstra T, Smit PG, Moddermam P, van Spronsen FJ. A different approach to breast-feeding of the infant with phenylketonuria. Eur J Pediatr. 2003 Abstract
  12. Cornejo V, Manríquez V, Colombo M, Mabe P, Jiménez M, De la Parra A, Valiente A, Raimann E. Fenilquetonuria de diagnóstico neonatal y lactancia materna. [Phenylketonuria diagnosed during the neonatal period and breast feeding]. Rev Med Chil. 2003 Abstract Full text (link to original source) Full text (in our servers)
  13. Motzfeldt K, Lilje R, Nylander G. Breastfeeding in phenylketonuria. Acta Paediatr Suppl. 1999 Abstract
  14. Duncan LL, Elder SB. Breastfeeding the infant with PKU. J Hum Lact. 1997 Abstract
  15. Riva E, Agostoni C, Biasucci G, Trojan S, Luotti D, Fiori L, Giovannini M. Early breastfeeding is linked to higher intelligence quotient scores in dietary treated phenylketonuric children. Acta Paediatr. 1996 Abstract
  16. Hinrichs F, Biggemann B, Wendel U. [Breast feeding of infants with phenylketonuria]. Klin Padiatr. 1994 Abstract

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