Is Lysine compatible with breastfeeding? Do we have alternatives for Lysine?


October 20, 2016 (Very Low Risk)

Lysine is an essential amino acid that is not produced by the body and must be taken from the diet.
It is found in large amount in legumes, cereals, red meat, sea fish, cheese and eggs. It is crucial for the synthesis of proteins in the body and multiple metabolic functions.
Often used as a dietary supplement without scientific evidence that would support any benefit of it.

Breastmilk contains it naturally with a highest concentration in the colostrum followed by a decrease within the first month after birth (Harper 1984, 1986 Janas, Spevacek 2015).
The concentration of lysine together with other amino acids and proteins is higher in the milk of mothers of preterm infants than in mothers of term infants (Atkinson 1980).
Pasteurization slightly decreases the concentration of lysine and other amino acids (Silvestre 2006, Valentine 2010) but increases the amount of bioavailable lysine (Baro 2011).

It is excreted into breast milk in clinically non-significant amount (0.5% of the administered dose) and as a part of proteins (Irving 1988, Thomas 1991).
When used as a supplementation is considered to be safe during breastfeeding (Amir 2011, The Royal Women's Hospital Fact Sheet 2013)


We do not have alternatives for Lysine since it is relatively safe.

Very Low Risk

Compatible. Not risky for breastfeeding or infant.

Low Risk

Moderately safe. Mild risk possible. Follow up recommended. Read the Comment.

High Risk

Poorly safe. Evaluate carefully. Use a safer alternative. Read the Comment.

Very High Risk

Not recommended. Cessation of breastfeeding or alternative.


  • Lysine Acetate
  • Lysine Hydrochloride


  • Λυσίνη (Greek)
  • ليزين (Arabic)
  • Лизин (Cyrillic)
  • 赖氨酸 (Chinese)
  • リジン (Japanese)
  • C6H14N2O2 (Molecular formula)


  1. Spevacek AR, Smilowitz JT, Chin EL, Underwood MA, German JB, Slupsky CM. Infant Maturity at Birth Reveals Minor Differences in the Maternal Milk Metabolome in the First Month of Lactation. J Nutr. 2015Abstract
  2. The Royal Women’s Hospital Victoria Australia. Herbal and Traditional Medicines in Breasfeeding. Fact Sheet. 2013 Full text (link to original source) Full text (in our servers)
  3. Baro C, Giribaldi M, Arslanoglu S, Giuffrida MG, Dellavalle G, Conti A, Tonetto P, Biasini A, Coscia A, Fabris C, Moro GE, Cavallarin L, Bertino E. Effect of two pasteurization methods on the protein content of human milk. Front Biosci (Elite Ed). 2011Abstract
  4. Amir LH, Pirotta MV, Raval M. Breastfeeding--evidence based guidelines for the use of medicines. Aust Fam Physician. 2011Abstract Full text (link to original source) Full text (in our servers)
  5. Valentine CJ, Morrow G, Fernandez S, Gulati P, Bartholomew D, Long D, Welty SE, Morrow AL, Rogers LK. Docosahexaenoic Acid and Amino Acid Contents in Pasteurized Donor Milk are Low for Preterm Infants. J Pediatr. 2010Abstract
  6. Silvestre D, Ferrer E, Gayá J, Jareño E, Miranda M, Muriach M, Romero FJ. Available lysine content in human milk: stability during manipulation prior to ingestion. Biofactors. 2006Abstract
  7. Thomas MR, Irving CS, Reeds PJ, Malphus EW, Wong WW, Boutton TW, Klein PD. Lysine and protein metabolism in the young lactating woman. Eur J Clin Nutr. 1991Abstract
  8. Irving CS, Malphus EW, Thomas MR, Marks L, Klein PD. Infused and ingested labeled lysines: appearance in human-milk proteins. Am J Clin Nutr. 1988Abstract
  9. Janas LM, Picciano MF. Quantities of amino acids ingested by human milk-fed infants. J Pediatr. 1986Abstract
  10. Harzer G, Franzke V, Bindels JG. Human milk nonprotein nitrogen components: changing patterns of free amino acids and urea in the course of early lactation. Am J Clin Nutr. 1984Abstract
  11. Atkinson SA, Anderson GH, Bryan MH. Human milk: comparison of the nitrogen composition in milk from mothers of premature and full-term infants. Am J Clin Nutr. 1980Abstract