Deciphering clues about aging from milk digestion

Eric Sibley has two stimulus grants stemming from his quest to understand how we handle lactose, the sugar in milk. The findings could lead to new understanding of what causes lactose intolerance, which could, in turn, have broader implications for research into human aging.

All mammals drink and digest milk as babies. While most mammals lose the ability to digest lactose as they mature, some humans retain this ability, a trait that appears to belie the normal aging process. Sibley hopes to understand better why this occurs by examining the exception: humans that are not susceptible to developing lactose intolerance.

Sibley, a pediatric gastroenterologist at Lucille Packard Children’s Hospital at Stanford, is using $100,000 in stimulus money to continue his work deciphering the molecular details of the genetic controls over lactose processing and gut maturation.

Sibley and his team have studied the gene in rats that instructs production of lactase, the digestive enzyme for lactose. (sugars end in “-ose,” their enzymes, in “–ase.”) The stimulus money will enable them to turn to the human version. In people, lactose intolerance makes milk annoying and sometimes distressing: It can cause bloating, gas and diarrhea as the ability to digest dairy disappears.

The funds allow purchase of specialized laboratory equipment to quantify gene function, and to follow the trail of fluorescently tagged molecules in the developing gut. Sibley hopes to follow exactly which proteins act to regulate lactase gene activity. The ability to recapture youthful molecular actions could be useful for more than just a happy tummy. Sibley’s work may one day provide insight and tools for dealing with other adverse effects of advancing age.

On another front, knowing the full story of these genes and their control points may make it possible for physicians to help children who suffer from congenital defects or require surgeries that leave them without portions of their intestine. By understanding how to control the genes that affect the digestion of lactose, it may some day be possible to steer the remaining parts of the intestine in these children to provide the missing functions.