Changes in small-intestine permeability with aging

J Am Geriatr Soc. 1995 Feb;43(2):160-4. doi: 10.1111/j.1532-5415.1995.tb06382.x.


Objective: To evaluate small-intestine mucosal integrity and permeability with advancing age as measured by the lactulose/mannitol absorption test in healthy subjects.

Design: Prospective cohort study.

Setting: Clinical research unit of the USDA Human Nutrition Research Center on Aging.

Study participants: Fifty-six subjects were recruited in three age groups: 20 to 39 years (n = 20), 40 to 59 years (n = 19), and > or = 60 years (n = 17). Subjects were healthy, community-dwelling volunteers.

Intervention: After an 8-hour fast, all subjects ingested 10 g of lactulose and 5 g of mannitol. Urine was collected for 6 hours and analyzed for lactulose and mannitol by high performance liquid chromatography. Twenty-four-hour urinary creatinine clearances were determined.

Main outcome measures: Percentages of lactulose and mannitol excreted, the lactulose/mannitol ratio (x100), and the 24-hour creatinine clearance.

Results: With increasing age, both the percentage of lactulose excreted (P = 0.09) and the percentage of mannitol excreted (P = 0.05) tended to decrease progressively. The lactulose/mannitol ratio (x100) did not change with increasing age (P = 0.65) because both the percentages of lactulose and mannitol excreted declined. The creatinine clearance decreased markedly with advancing age (P < .001) and accounted for the decline in percentages of lactulose and mannitol excreted (P < .02).

Conclusions: There is a progressive decline in the ability to excrete lactulose and mannitol with increasing age. This is probably attributable to a decline in renal function with advancing age. However, because of parallel decreases in lactulose and mannitol excretion, the lactulose/mannitol ratio does not change. Thus small-intestine "leakiness" does not increase with aging as measured by the lactulose/mannitol absorption test.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aging / physiology*
  • Cohort Studies
  • Creatinine / blood
  • Female
  • Humans
  • Intestinal Absorption
  • Intestinal Mucosa / physiology
  • Intestine, Small / physiology*
  • Lactulose / urine
  • Male
  • Mannitol / urine
  • Middle Aged
  • Permeability
  • Prospective Studies


  • Mannitol
  • Lactulose
  • Creatinine