Subject: Re: Eating Corn
From: mannj@southern.co.nz (Jay Mann)
Date: Jun 06 1996
Newsgroups: misc.fitness.misc

oanews (dchill@relay.nswc.navy.mil) wrote:
: Nobody doubts that corn has 89 Kcal per 1/2 cup. The question is:
: When the corn passes through a body unscathed, what happens to
: those Kcals?  It seems clear to me that if one measures input
: calories, one must measure output calories in order to
: get retained calories which may become energy or fat. Most
: diets don't talk about output calories. I maintain that any diet
: that talks about input calories but doesn't talk about output
: calories is worthless.

It's not enough just to measure output calories.  A lot of the 
short=chain carbohydrates (oligosaccharides) don't get absorbed in the 
small intestine but instead go to feeding the bacteria of your large 
intestine. (About half the volume of faeces is provided by bacteria.) So 
you need to find out what is known as "ileal digestibility", that is, 
what is utilized by the mammal.  

My only information pertains to pigfeed; pigs have very similar 
metabolism to humans.  Dried corn ("maize") is a standard ingredient of 
pig diets, e.g., 78.4% in one example (NRC, NAS).  Mature corn is 
regarded as a high-energy feed, with lots of available digestive energy, 
about 3500 kcal per kg. Immature sweet corn certainly has far less starch 
and a lot more poorly digested oligosaccharides, which may interfere 
somewhat with absorption of other nutrients.

The ileal digestibility of corn amino acids is 70-80%, about the same
range as other feedstuffs. I don't have any info on carbohydrate ileal
digestibility.  The usual way to measure ileal digestibilty in animals is
an operation in which a valve or shunt is inserted at the junction of
small and large intestines. Any volunteers? 

Jay D Mann  <mannj@southern.co.nz>
Christchurch, New Zealand

Subject: Re: Does fiber really count as carbohydrate?
From: mannj@southern.co.nz (Jay Mann)
Date: Jun 03 1996
Newsgroups: misc.fitness.misc,sci.med.nutrition

Sam Callan, grad student (gs02sdc@panther.Gsu.EDU) wrote:
: Fiber can be used as an energy source for the flora/bacteria in the small 
: intestine.
: 
: RDA for fiber is 25-30g/day
 

Right on.  The usual way for estimating food calories is seriously flawed 
because it only measures the difference between what goes in the mouth 
and what comes out the other end.  Whether the nutrients are utilized by 
the person or animal through absorption in the stomach and small 
intestine ("ileum"), or whether they go to make the micro flora in the 
large intestine (not the _small_ intestine, by the way) -- doesn't affect 
the calculations, although it does affect your calorie balance.  The 
medium-chain oligosaccharides of beans, for instance, aren't digested by 
animals but contribute instead to gas-forming bacteria in the bowels.  

There's no easy way around this problem, unless someone would like to 
volunteer to have some hardware inserted at the junction of their small 
and large intestines.   And there's no easy chemical way to correct.  For 
instance, there's something called "resistant starch" which passes right 
through.  The amount of "resistant starch" found depends on the 
analytical technique used, e.g., enzymes or acid, whether the starch is 
heated (gelatinized) or not.  Raw potato starch is all "resistant" 
according to one method, but not at all resistant according to another one.

Jay D Mann  <mannj@southern.co.nz>
Christchurch, New Zealand