How long does food stay in my stomach? How long is it before a meal reaches the large intestine? The answer to such commonly-asked questions is not necessarily simple. First, there is considerable normal variability among healthy people and animals in transit times through different sections of the gatrointestinal tract. Second, the time required for material to move through the digestive tube is significantly affected by the composition of the meal. Finally, transit time is influenced by such factors as psychological stress and even gender and reproductive status.

Several techniques have been used to measure transit times in humans and animals. Not surprisingly, differing estimates have been reported depending on the technique used and the population of subjects being evaluated. Some of the techniques used include:

Radiography following a barium-labelled meal. Sequential radiographs can be used to determine when the front of the barium label reaches different regions of the digestive tube. Such meals are not very physiologic and the technique exposes the patient to repeated exposure to radiation.
Breath hydrogen analysis. A number of carbohydrates are very poorly digested or absorbed in the small intestine, but readily fermented by bacteria when they reach the large intestine. Fermentation liberates hydrogen gas, which diffuses into blood and is exhaled in breath, where it can be readily measured. Thus, after consumption of a meal containing a non-absorbable carbohydrate (lactulose or, more commonly, baked beans), there is a large increase in exhaled hydrogen when the carbohydrate reaches the large intestine. This provides an estimate of pre-colonic (stomach plus small intestine) transit time.
Scintigraphic analyses. Meals containing pellets or colloids labelled with a small amount of radionuclide (99mTechnetium, 113mIndium, etc.) are consumed, and the position of the radioactive label is sequentially monitored using a gamma camera.
Studies of gastrointestinal transit have clearly demonstrated two related phenomena important to understanding this process:

Substances do not move uniformly through the digestive system.
Materials do not leave segments of the digestive tube in the same order as they arrive.
In other words, a meal is typically a mixture of chemically and physically diverse materials, and some substances in this mixture show accelerated transit while others are retarded in their flow downstream.

An example of how ingested substances spread out in the digestive tube rather than travel synchronously is shown in the figure below. These data were obtained from a human volunteer that ingested a meal containing 111Indium-labeled pellets, then measuring the location of the radioactive signal over time by scintigraphy. It is clear that parts of the meal are entering the colon at the same time that other parts are still in the stomach.

The discussion above should help to explain why it is difficult to state with any precision how long ingesta remains in the stomach, small intestine and large intestine. Nonetheless, there have been many studies on GI transit, and the table below presents rough estimates for transit times in healthy humans following ingestion of a standard meal (i.e. solid, mixed foods).

50% of stomach contents emptied 2.5 to 3 hours
Total emptying of the stomach 4 to 5 hours
50% emptying of the small intestine 2.5 to 3 hours
Transit through the colon 30 to 40 hours

Remember that these are estimtes of average transit times, and there is a great deal of variability among individuals and in the small person at different times and after different meals.
http://www.vivo.colostate.edu/hbook...cs/transit.html

The pineapple is very LIKELY not a part of the crime, and was eaten before going to the White's.

http://www.webbsleuths.org/dcforum/DCForumID61/1434.html#1

Digestive rates are variable from person to person and in the individual. Simply because you digested chocolate cake in two hours on Monday doesn't mean you will digest it in two hours on Tuesday or any other day.

From Corpse by Jessica Snyder Sachs:

At this point in the trial, a prosecutor brought four large Styrofoam cups to the witness stand. Baden (Michael Baden) opened each in turn, held them to his nose, and identified them as the gastric contents of Susan Hendricks and her three children. He described how the quantity and quality of the foodstuffs in the children's stomachs--fragments of mushrooms olives, and onions--indicated they had died approximately two hours after finishing their 7PM pizza. Three more prosecution witnesses, including the chief medical examiner of Dade County, Florida, and the chief toxicologist for the Illinois Department of Public Health, supported Baden's opinon.

But the battle of the medical experts had just begun. The defense called to the stand four equally renowned forensic pathologists who testified that time of death could never be pinpointed by something as variable as digestion. Althoug a typical meal takes two to four hours to pass out of the stomach, a hundred different factors could speed or delay the process, they argued. Factors such as the excitement children experience during a special night on the town? asked a defense attorney. Factors such as gulping food in large bites, as children do when they're in a rush to get back to their play? Factors such as strenuous physical activity, say, jumping on an air-pillow trampoline, climbing rope ladders, and 'swimming' through a vat of plastic balls?

Earlier, the prosecutor's own medical witnesses had discounted the possibility that such "normal" activities would significantly impact children's digestion. "If it did, my seven children and eleven grandchildren would be suffering from indigestion all the time," one had quipped. By contrast, the witnesses for the defense argued that the medical literature supported their opinion that such things can and do slow digestion though not in a predictable way. One cited the example of an eleven-year-old murder victim known to be alive more than four hours after he ate a pizza lunch at school, a boy whose stomach contents on autopsy were more than double the amount of the stomach contents of the three Hendricks children combined.

In other words, the time it takes for food to pass out of the stomach after ingestion is highly variable and should not be used as a time-of-death indicator unless it is KNOWN (corroborative evidence) when the victim last ate.

The statistics we find on the internet and through other sources are labeled "normal." Normal is a bit like average in that a great amount of data is collected and the 'norm' is found after studying the extreme ends of that data and all that lies within.

This is one of the reasons Dr. Meyer did not attempt to pin point a time-of-death for JonBenet but instead offered a general time. Pinpointing T0D is an inaccurate science given what we know about digestive rates, body temps, livor mortis, etc. Even insect activity has variables even though many of them are very precise in their breeding/larval/pupae stages.

Rainsong

>Excellent post, Rainsong.
>
>Given the circumstances of a child's murder, I have to
>wonder WHY Dr. Meyer did not perform some of the other TOD
>tests.

There really aren't any 'tests' for TOD. The potassium level in the eye thingy hasn't proved to sound since no one knows what the 'norm' is for any particular living person. Livor mortis takes a certain amount of time to develop as does rigor. Body temp was also taken at the time Dr. Meyer arrived at the Ramsey home. All of those criteria were taken into consideration when he gave his guesstimate.

Corpse, the book I cited above, is a detailed analysis of the search for the 'smoking gun' of TOD.

From the book:

"Even today, despite crime labs crammed with high-tech equipment for DNA analysis, toxicology, serology, and the detection of rarefied chemical vapors, we remain nearly as blind as the ancient Greeks with their belief in maggots sprouting fully formed and spontaneous from the flesh of the newly dead.

"Nonethelss, it still startles people to learn that a prudent medical examiner can rarely, if ever, accurately measure the interval between death and a body's discovery."

And this tidbit:
"Twentieth-century pathologists added stomach contents to the factors that might suggest time of death. Unlike the other three clocks (rigor, livor and algor mortis) set in motion at death, digestion slams to a halt. In theory at least, a medical examiner who knows the approximate time and quantity of the victim's last meal should be able to extrapolate time of death based on the rate that food might be expected to pass out of the stomach and into the intestines.In reality, the vagaries of stomach emptying in the soon-to-be-dead have proven even more problematic than the postmortem markers of rigor, livor and algor."

It is intersting to note that in the case of Gerald Boggs, stomach contents were quite important in discerning his estimated TOD and helped convict his wife.

Just another little footnote on the oddity of homicide.

Rainsong