By food value or nutritive value we ordinarily mean the amount of organic nutrients present in the food. In determining the importance of any particular food, we consider not only the total amount of the nutrients present, but the relation that the proteid bears to the other nutrients. This is often called the nutrient ratio. The nutrient ratio of potatoes, for example, containing two per cent of proteid and eighteen of starch, is 1 to 9. In reckoning this ratio, fat is changed into its starch equivalent, that is, one part of fat is considered equal to two and a quarter of starch.

Classification Of Foods

The following classification of the food principles may help to fix in the mind their relationship.

Nutritive Ingredients (Or Nutrients) Of Food

Organic.

Nitrogenous......

Proteids, e.g., albumin, casein, gluten, etc.

Gelatinoids, e.g., gelatine, etc.

Extractives.

Non-nitrogeneous

Carbohydrates, e.g., sugar, starch.

Fats.

Inorganic

Mineral matters.

Water

Use Of Food Principles In The Body

Proteid .................................Forms tissue

All serve as fuel to yield energy in the forms of heat and muscu-lar power

eg , white (albumen)

of eggs, curd (casein)

of milk, lean meat,

gluten of wheat, etc.

Fats....................Are used or stored as fat........

e.g., fat of meat, but-

ter, olive oil, oils of

corn and wheat, etc.

Carbohydrates ..................Are used or transformed into fat.

e.g., sugar, starch,etc.

Mineral matters (ash).. Share in forming bone, assist in digestion, etc.

e.g., phosphates of

lime, potash, soda, etc.