Wednesday, 1 August 2012

On Digestion

BBC Radio 4's Inside Health has a good bit, concerning digestion (starting at around the 25 minute mark). It features Dr Anton Emmanuel, a consultant neuro-gastroenterologist who makes the following points:
  • Digestion Speed - it can take 8-36 hours to digest food, depending on factors like your emotions, food type and 'personal makeup'!
  • Peristalsis (the mechanism that drives food through the gut) - "The wavelike muscular contractions of the alimentary canal or other tubular structures by which contents are forced onward toward the opening". The muscle and nerves in our guts coordinate stomach, small intestine, colon, all the way to tail end (anus).  The brain can influence peristalsis (up-regulate or down-regulate transit time), via the autonomic nervous system (involuntary nervous system).
  • Most nutrients are absorbed in just 15ft of small bowel in a transit time of about two 2 hours.
  • The bulk of transit time is in the colon where water is rung out of the food (saliva, gastric acid, small bowel juices and consumed liquids).
  • Of particular note, fast transit times don't interfere with nutritional absorption!

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