MadSci Network: Medicine

Re: Re: How long does it take to get carbohydrates we eat into our bloodstream?

Date: Tue Oct 12 16:31:20 2004
Posted By: Peter Bosani,
Area of science: Medicine
ID: 1096077877.Me

Hello, Aung.

Exact timelines of the absorption of carbohydrates are difficult to 
pinpoint as many variables exist.  For example, the smaller the stomach, 
the more rapidly it empties, or how well the food is cooked and/or chewed, 
to whether it's a solid or liquid, and the amount of fiber or fat along 
with the carbs., as well as stress levels and one's physical condition can 
all influence the transit time and absorption of carbohydrates.
However I'll try to clarify it somewhat for you.  Carbs. actually begin 
their breakdown in the mouth.  It takes about 12 seconds for food to reach 
the stomach.  Fluids can reach the stomach in as litle as 1 second.  Food 
stays in the stomach on average about 4 hours, but can range from one to 
six hours depending on the meal.  (A light meal can be emptied after one 
hour).  Carbs. get preferential treatment because they are emptied ahead 
of other nutrients.  The end products of carbohydrate metabolism are 
called monosaccharides, or simple sugar.  Once food reaches the small 
intestine, digestion proceeds rapidly.  A meal stays in the small 
intestine an average of 4 1/2 hours, but can range between 2 1/2 to 8 
hours.  So it would take a minimum of about 2 hours, (give or take 30 
minutes), from the time you've begun eating until the absorption of 
carbohydrates.  This estimate could easily be double, i.e. at least 4 
hours,  depending on what else is being consumed along with the 
carbohydrates.  Also, keep in mind that digestion of an entire meal can 
take between 5 to 9 hours, prior to absorption.
There are special circumstances where sugar is absorbed far more quickly,  
For example, a standard test known as the glucose tolerance test is given 
to challenge the body's response to dietary glucose.  This helps establish 
one's status or risk towards the development of diabetes.  Glucose is 
administered in a liquid form after a fast of 12 hours.  Blood sugar is 
checked prior to drinking the glucose in order to establish a baseline, 
and then blood samples are subsequently withdrawn at regular intervals to 
be analyzed and compared to normal nondiabetic values.  Certainly, after 
30 minutes blood glucose levels have shot up 50 to 60 mg/100ml. in a 
normal nondiabetic individual.  The effects of consuming the sweetened 
based drink actually begins to affect glucose levels after only 5 
minutes!  Keep in mind though, that this test is done with a liquid, on an 
empty stomach, after a fast, all of which will speed glucose into the 
intestine for immediate absorption.  Another example  is seen with 
hypoglycemics, a condition of low blood sugar.  "Following oral 
administration of 10 to 20 grams of dextrose, increases in blood glucose 
usually occur within 10 to 20 minutes and peak at about 40 minutes.  In 
one study following oral administration of a 20 gram dose of dextrose as 
tablets, mean blood glucose concentration increased by 32 mg./Dl 20 
minutes later in hypoglycemic patients." (1.)
So as you see, there are may different factors that can affect the timing 
of the absorption of carbohydrates into the bloodstream, but I hope I've 
given you a better idea.

Your mad scientist,

Peter Bosani.

References:  (1.) American Hospital Formulary Service Drug Information - 
                  Encyclopedia and Dictionary of Medicine, Nursing, and 
Allied Health - Miller. Keane
                   Food, Nutrition and Diet Thereapy - Krause 

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