THE ROUGH STUFF

New Zealand Listener, Volume 8, Issue 203, 14 May 1943, Page 10

THE ROUGH STUFF

(Written tor "The ‘ Listener" by DR.

MURIEL

BELL

Nutritionst to the Department of Health)

tems in a healthy state, it is necessary that our foods should contain, in addition to Vitamin B, a certain amount of those materials which are not attacked by the digestive juices; those undigested residues promote the normal movements of the’ intestines. There have been some interesting points coming to light about the different substances which are grouped under the term "roughage," and which the chemist designates respectively as lignin, cellulose and hemicellulose, The tougher of these materials can truly be labelled as the "rough stuff’; to some people’s intestines it is irritating. The skins of certain fruits and seeds come into this category. Bran, for example, cannot be tolerated by some people’s insides; it is certainly better left out of the diet of infants. Course oatmeal, cooked and then strained through a sieve will get over | the difficulty for infants or for those with gastric ulcer or other diseases of the gastro-intestinal system. [= order to keep our digestive sysThe constituents of plant cells which are particularly valuable are those which have the property of swelling in water, and holding on to the water when they are in the intestines. The wall of the large bowel has the power of absorbing water, it acts in competition with these water-absorbing substances present in plant cells. The class of "roughage" known as hemicellulose is not really rough at all, but acts in virtue of this power to attract and to hold on to water. Thus they provide soft, nonirritating bulk, in virtue of their properties as colloids, as the chemists call them. Some of these colloids are capable of taking up from 10 to 70 times their own weight of water. Among these softer forms of roughage (if we are permitted to use contradictory terms), are the pectins present in fruits and vegetables. This is why fruits and vegetables are so necessary for keeping us regular. One medicinal form of soft "roughage" which was formerly obtainable was a Japanese seaweed known as agar-agar. It was one of the best forms of laxative, because it came from a natural foodstuff. Incidentally, it had mary other uses besides its value as a laxative. These uses are summarised in a very interesting bulletin on seaweeds (No. 85), by Miss Moore of the Plant Research Bureau, Wellington, who suggests that as substitutes of agar, our species of > seaweed known as Pterocladia, and Gelidium, and possibly others, could be used as a source of commercial manufacture.