There are four letters in the food alphabet: _A_, fuel for the body machine; _B_, protein for the upkeep of the machinery; _C_, mineral salts, partly for upkeep and partly for lubrication--to make all parts work smoothly together; _D_, vitamines, subtle and elusive substances upon whose presence depends the successful use by the body of all the others.

These four letters, rightly combined, spell health.

They are variously distributed in food materials.

Sometimes all are found in one food (milk for example), sometimes only one (as in sugar), sometimes two or three.

The amounts also vary in the different foods.