The Chemistry of Food and Nutrition | Page 6

Englishman going to a tropical country and partaking
largely of flesh and alcohol, suffers from disease of the liver and other
organs, to which the natives and the few of his own countrymen, living
in accordance with natural laws are strangers.
Indigestible Matter--Food is never entirely digested. As a reason

against confining ourselves solely to vegetable food, it has been stated
that such is less perfectly digested than animal food and that it therefore
throws more work on the digestive organs. It is also urged that on this
account a greater quantity of vegetable food is required. We have
shown elsewhere that, on the contrary, vegetarians are satisfied with a
smaller amount of food. Man requires a small quantity of woody fibre
or cellulose in his food to stimulate intestinal action and prevent
constipation.
It is difficult to determine how much of a food is unassimilated in the
body. This is for the reason of the intestinal refuse consisting not only
of undigested food, but also of residues of the digestive juices, mucus
and epithelial debris. These latter have been shown to amount to from
one-third to one-half of the whole of the fæces, which is much more
than had previously been supposed.
John Goodfellow has shown that of very coarse wholemeal bread quite
14 per cent. was undigested, whilst bread made from ordinary grade
wholemeal showed 12.5 per cent. Such a method of analysis was
adopted as it was believed would exclude other than the food waste.
The experiments were made on a person who was eating nothing but
the bread. It seems probable that a smaller proportion would have
remained unassimilated had the bread not formed the sole food. It is
advisable that wheatmeal he ground as finely as possible, the coarse is
not only to a less extent assimilated but apt to irritate the bowels.
Notwithstanding that fine white bread gave only 4.2 per cent. and a
coarse white bread 4.9 per cent. of waste, a fine wheatmeal bread is
more economical as the same quantity of wheat produces a greater
weight of flour richer in proteid and mineral matter. From a large
number of experiments with man, it has been calculated that of proteids
there is digested when animal food is eaten 98 per cent., from cereals
and sugars 8 per cent., from vegetables and fruits 80 per cent. The
difference between the proportions digested of the other food
constituents was much less. Although there is here a theoretical
advantage in favour of animal food, there are other considerations of
far more importance than a little undigestible waste. The main question
is one of health. In some dietary experiments of a girl aged 7, living
upon a fruit diet, of whom we have given some particulars elsewhere,
Professor Jaffa gives the following particulars. During the ten days trial

the percentages absorbed were proteids 82.5, fat 86.9, nitrogen free
extract 96, crude fibre 80, ash 5.7, heat of combustion in calories 86.7.
He says, "generally speaking, the food was quite thoroughly
assimilated, the coefficients of digestibility being about the same as are
found in an ordinary mixed diet. It is interesting to note that 80 per cent.
of the crude fibre appeared to be digested. The results of a number of
foreign experiments on the digestibility of crude fibre by man are from
30 to 91.4 per cent., the former value being from mixed wheat and rye,
and the latter in a diet made of rice, vegetables and meat."
TABLE OF ANALYSIS OF FOOD
Key: P = Proteins. Cb = Carbohydrates. C = Cellulose. R = Refuse. W
= Water. Ca = Calories.
Nt'nt P. Fat. Cb. Ash. C R W Ca Ratio Wholemeal, G. 14.9 1.6 66.2 1.7
1.6 ... 14.0 1577 4.68 Fine Flour, G. 9.3 0.8 76.5 0.7 0.7 ... 12.0 1629
8.4 Medium Flour, G. 12.1 0.9 72.2 0.9 0.9 ... 13.0 1606 6.13 Bread,
Wholemeal, G. 12.2 1.2 43.5 1.3 1.8 ... 40.0 1086 3.8 Bread, White, G.
7.5 0.8 53.8 0.9 ... ... 37.0 1174 7.4 Macaroni, U. 13.4 0.9 74.1 1.3 ... ...
10.3 1665 5.67 Oatmeal, D. 14.8 9.6 63.3 2.2 1.4 ... 8.7 1858 5.72
Maize, American, S. 10.0 4.25 71.75 1.5 1.75 ... 10.75 1700 8.12 Rice,
husked, U. 8.0 0.3 79.0 0.4 ... ... 12.3 1630 10.0 Rye Flour, U. 6.8 0.9
78.3 0.7 0.4 ... 12.9 1620 11.8 Barley, Pearl, C. 6.2 1.3 76.0 1.1 0.8 ...
14.6 1584 12.7 Buckwheat Flour, U. 6.4 1.2 77.9 0.9 ... ... 13.6 1619
12.6 Soy Bean, C. 35.3 18.9 26.0 4.6 4.2 ... 11.0 1938 1.93 Pea-nut, C.
24.5 50.0 11.7 1.8 4.5 ... 7.5 2783 5.2 Lentils, U. 25.7 1.0 59.2 5.7 ... ...
8.4 1621 2.4 Peas, dried, U. 24.6 1.0 62.0 2.9 4.5 ... 9.5 1655