Intestinal permeability to intact lactose in newborns and adults

Jorge A. Bezerra, Steve H. Thompson, Mark Morse, Otakar Koldovský, John N. Udall

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Small amounts of lactose have been shown to be absorbed intact across the intestine and excreted unchanged in the urine of newborns and adults. We designed a study to quantitate the intestinal uptake and urinary excretion of this disaccharide in these age groups. Similar amounts of lactose were given orally to 17 term newborns (age: 24.8 ± 3.0 h) as a standard infant formula, and to 15 adult lactose absorbers (age: 28.1 ± 2.6 years) and 11 adult lactose malabsorbers (age: 24.7 ± 2.9 years) as a 20% water solution. Following lactose ingestion, breath was collected every 30 or 60 min for 3 h and analyzed for hydrogen concentration. Urine was also collected, and lactose and creatinine concentrations were determined. Peak hydrogen concentration was <20 ppm above baseline in newborns and adult lactose absorbers and 85 ± 14 ppm in adult lactose malabsorbers. Urinary lactose excretion, expressed as a function of body weight (mg/ml/kg b.w.), was substantially greater in newborns (4.2 ± 0.82) than in adult lactose absorbers (0.29 ± 0.07; p < 0.001) and adult lactose malabsorbers (0.55 ± 0.04: P < 0.01). Similarly, urinary lactose excretion expressed as a ratio of urinary lactose to urinary creatinine (mg/mg) was increased (p < 0.001) in newborns (2.05 ± 0.26) when compared to adult lactose absorbers (0.11 ± 0.02) and adult lactose malabsorbers (0.20 ± 0.02). Our data demonstrate that the intestinal uptake and urinary excretion of intact lactose is significantly increased in newborns compared to adult subjects.

Original languageEnglish (US)
Pages (from-to)334-342
Number of pages9
Issue number6
StatePublished - 1990
Externally publishedYes


  • Infants
  • Lactose absorption
  • Urine lactose

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Developmental Biology


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