fths from vegetable
sources.

249. Animal and Vegetable Foods; Economy of Production.--Animal foods
can never compete in cheapness of the nutrients with cereals and
vegetables, as it takes six to eight pounds or more of a cereal,
together with forage crops, to make a pound of meat. Hence the returns
in food value are very much larger from the direct use of the cereals as
human food, than from the feeding of cereals to cattle and the use of
the meat. As the population of a country increases, and foods
necessarily become more expensive, cereals are destined to replace
animal foods to a great extent, solely as a matter of economy.

250. Food Habits.--Long-established dietary habits and customs are not
easily changed, and when the body becomes accustomed to certain foods,
substitution of others, although equally valuable, may fail to give
satisfactory results. For example, immigrants from southern Europe
demand foods with which they are familiar, as macaroni, olive oil, and
certain kinds of cheese, foods which are generally imported and more
expensive than the staples produced in this country,[80] and when they
are compelled to live on other foods, even though they have as many
nutrients, they complain of being underfed. Previously acquired food
habits appear to affect materially the process of digestion and
assimilation. Sudden and pronounced change in the feeding of farm
animals is attended with unsatisfactory results, and whenever changes
are made in the food of either humans or animals they should be gradual
rather than radical.

251. Underfed Families.--As the purchasing of food is often done by
inexperienced persons, palatability rather than nutritive value is made
the basis of choice. Dietary studies show that because of lack of
knowledge of the nutritive value of foods, whole families are often
underfed. Particularly is this true where the means for purchasing foods
are limited. In dietary studies among poor families in New York
City,[81] the United States Department of Agriculture notes: "It is
quite evident that what is needed among these families more than
anything else is instruction in the way to make the little they have go
the farthest." Some classes of the rich too are equally liable to be
underfed, as they are more prone to food notions and are able to indulge
them. Among the children of the rich are found some as poorly nourished
as among the poor.

252. Cheap and Expensive Foods.--Among the more expe