Estimate digestion time

[Bimathax]

Hello everyone,

I'm trying to time digestion but I don't know how to do it(it's for a school project)...
I thought to measure the glycemia rate (blood sugar level) : 

     -Before the meal : get the initial value

     -After the meal : the rate increases because of the new nutrients

     -Test every 20min to see when it decreases

By this way, I would be able to know how long the digestion process takes for a specific type X of food...

So, I would know if my protocol is good and what else I can do to time my digestion.

I'm open to any thoughts and ideas...

Thank you !

[exchemist]

27 minutes ago, Bimathax said:

Hello everyone,

I'm trying to time digestion but I don't know how to do it(it's for a school project)...
I thought to measure the glycemia rate (blood sugar level) : 

     -Before the meal : get the initial value

     -After the meal : the rate increases because of the new nutrients

     -Test every 20min to see when it decreases

By this way, I would be able to know how long the digestion process takes for a specific type X of food...

So, I would know if my protocol is good and what else I can do to time my digestion.

I'm open to any thoughts and ideas...

Thank you !

It doesn’t seem simple to me. Residence time in the stomach is one thing, but that’s just the start. Absorption of nutrients in the small intestine can take a long time. And do you count the further processing and recovery of water and salts in the large bowel?

[TheVat]

1 hour ago, Bimathax said:

 

By this way, I would be able to know how long the digestion process takes for a specific type X of food...

 

(Delighted to find a question concerning a field in which I have formal training) 

Measuring blood glucose will not be a reliable measure here.

A specific food is usually a complex blend of nutrients which, as they make their way through the small intestines, are absorbed through the villi at different rates.  Most nutrients pass through the mucosa layer of villi in the jejunum, however some minerals absorb in the duodenum.  Coffee leaves the stomach in as little as ten minutes and is absorbed shortly thereafter, while ruminant meat might take several hours to leave the stomach and then as long as a day to be absorbed in the intestine.  A white flour pastry with minimal oils could be absorbed in a fraction of the time of meat or fatty foods.  Same for fruit juices.  Whole wheat moves slower and absorbs slower due to high dietary fiber content.  Whole rolled oats are also slower, with even slower mineral uptake due to phytic acid content.  (Many foods have so-called anti-nutrients, which are chemicals that actually block complete digestion and reduce specific nutrient absorption.) 

There are also resistant starches, mainly polysaccharides, which due to various features (like amylase resistant cellular walls) are simply not digested by us, but nevertheless contribute to colon health and feed intestinal flora we need.  Lentils, green bananas, dates, and many other foods have these resistant starches.  Soluble fiber and resistant starch are quite similar, and there is some overlap.  

Anyway, point is, you have to look at what goes in to making a specific food, and learn how its components will be absorbed at different rates.   The table sugar on that doughnut may absorb in under an hour, while oleic acid, an omega-9 fatty acid in the cooking oil, will take longer to access.