Thursday, January 20, 2011

How we digest fat

Spark was reading about the stomach digesting fat and he did this little experiment.  Using two glasses he filled them with warm water.  Into each glass he poured a dollop vegetable oil.  He wanted to use olive oil, but after a little discussion on the cost of olive oil, he made the wise choice to use the vegetable oil and will not be making the mistake again of thinking of using olive oil for a science experiment.  He put a couple drops of food coloring in each glass to make the oil stand out better.

The drops of oil in the glass were really large.  To show how intestinal peristalsis, a rhythmic movement of your stomach that moves food downward, breaks up the fat molecules (triglycerides) he stirred the oil in the glasses.

When the water and oil was stirred it broke apart the oil into smaller blobs.

In our stomachs after the fat is broken down, pancreatic enzymes (in our case a squirt of dish soap) then digest the fat into smaller fragments.

Bile formed in the liver keeps the little fat molecules from separating out of the watery chyme (the semi-fluid mixture of food and gastric fluids that pass from the stomach to the small intestine).  The fat molecules are broken into small fragments, then enter the absorptive cells (villi) of the intestinal lining.  After being absorbed into the body they recombine into large globs and are sent into the lymphatic vessels that deliver them to the general circulation.

In the 1970's Proctor & Gamble developed a fat called Olestra (or Olean).  This is a modified fat that is too large to be absorbed into the body.  Because it is not absorbed the calories of the fat pass through the body.  It is available today in various chips and crisps like Pringles lite and Lay's Potato Chips Lite.  Unfortunately there are side effects when eating olestra.  The FDA required a warning: This Product Contains Olestra. Olestra may cause abdominal cramping and loose stools. Olestra inhibits the absorption of some vitamins and other nutrients. Vitamins A, D, E, and K have been added."

Are there any benefits from Olestra?  Sure, Olestra, like any fats, absorbs dioxin poisons.  Unlike other fats, the olestra and dioxin are not reabsorbed by the body.  The chemical is also used as an industrial lubricant and as a paint additive (don't be grossed out, lots of edible products have industrial uses).

Difficulty digesting fat can cause steatorrhea, that is fatty, or oily stool.  This symptom may help diagnose physical problems such as gall bladder disease, liver problems or pancreatic problems.

Spark thought this was just the coolest topic and experiment, he made sure we all came over and checked out his work.

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