The name is absent

178    Vitamins in Human Nutrition

is made slightly alkaline by addition of soda it loses 30 to 40
per cent of its thiamin and nearly all its vitamin C. In
ordinary processes of cooking or canning of fruits and
vegetables in which the juice is not discarded the thiamin
content is fairly well preserved, quite in contrast to the
severe destruction of vitamin C which occurs in many such
products. The high temperatures required for canning vege-
tables and meats, however, result in a considerable destruc-
tion of their thiamin.

Although the inclusion of too much white bread in the
diet only rarely leads to out-and-out beri-beri, it not infre-
quently leads to less obvious injury, such as loss of appetite,
constipation, indigestion, weakness, and loss of weight. This
is particularly likely to happen in American homes where
white sugar, another refined food, has come to contribute
much too large a proportion of the calories in the food.
The average per capita consumption of sugar in America
has increased nearly tenfold in the last hundred years. Since
so much sugar is eaten, providing many calories but no
vitamins, it is inevitable that some of the other foods will
have to be particularly rich in thiamin, or else so much of
them will have to be eaten in addition to the sugar that
there will be an excess of calories and a consequent outbreak
of bulging waistlines and double chins. The great American
diet of steak, potatoes, white bread, and sugar is un-
doubtedly inadequate in thiamin unless the potato item and
accessories are high in proportion to the sugar and bread.

There is still some uncertainty about the exact manner in
which thiamin affects the body, and particularly the nerves,
but one reason for its indispensability has definitely been
pinned down to the fact that without it the metabolism of
carbohydrates beyond the pyruvic acid stage (just before
its final conversion into CO₂ and water) is interfered with,

<<   7   8   9   10   11   12   13   >>

More intriguing information