Re: Does the core of lettuce make a person constipated?

You are correct that foods containing dietary fiber, such as lettuce, are 
good for our digestive systems.  In fact, most plant foods contain fiber.  
One type of dietary fiber is cellulose.  Dietary fibers are defined as 
those carbohydrate-based materials that our bodies are unable to digest.  
Most of us do not eat the 25-35 grams of fiber a day that most health 
organizations, such as the American Cancer Society, recommend.  Lettuce 
leaves are about 1.4% fiber, with about 80% of that cellulose (reference, 
USDA Handbook No. 8, Composition of Foods).  The core has more cellulose 
than the leaves and would also contain lignin, another type of fiber.  
However, I was unable to find an exact amount of fiber in the core of 
lettuce, but it would be greater than that of the leaves.  
     People can become constipated if they suddenly begin consuming a high 
fiber diet, particularly if they do not also increase their consumption of 
water.  Therefore, the recommendations are to increase fiber intake 
gradually over a period of a few weeks.  Therefore, if a person were not 
accustomed to consuming a relatively high fiber diet and consumed a 
significant amount of lettuce cores(which means one or more), they might 
experience constipation.  However, this is only due to the sudden 
increase in fiber intake and not to other components of the lettuce.