While in most cases cooking means a devitalization of the nutritional elements of the food, and may even seriously impair their digestibility, yet the devotees of raw or "un-fired" diet should not ignore the other fact, that in case of functional weakness, an individual, to restore his enfeebled digestion, may need the very change of physiological chemistry which the cooking of food brings about.
In order to insure the greatest nutritional results, we must take into consideration not only the laws and characteristics inherent in the foodstuff itself, but likewise the constitutional efficacy of the digestive powers of the individual. The motive back of diet should not consist in a mere catering to a person's taste and cravings, but rather in an effort to raise his digestive and assimilative powers to stages of highest efficiency, taking into account both the nature of the food itself and the physiological reaction involved in the digestive process.
There are reasons for believing that to the majority of mankind the digestibility of certain foodstuffs are improved by cooking. To this class of foods belong starch. Exposed to a certain excess of heat, the cellulose, enveloping the starch-cells, swells and bursts open, rendering its contents accessible to the ptyalin ferment of the salivary and intestinal secretions. From this it follows that as an article of diet, any foodstuff highly charged with starch is improved by cooking. Thus rice, with its 85 per cent; rye, 71 per cent; wheat, 70 per cent; oats 67 per cent, and most of the grains and pulses, which are highly charged with starch, derive their available nutritional value from an excessive exposure to heat.
On the other hand, such foodstuffs as are rich in albuminous elements require an altogether different treatment, and may even be rendered detrimental through cooking, as the very heat which opens the starch-cell to induce the action of the digestive ferments, is found to close the albuminous cell, through the process of coagulation, - a condition by which the food becomes utterly impervious to the action of digestion. Hence the advisability of serving such highly albuminous substances as eggs, milk, and most of the leaf vegetables - especially celery - in their raw, unprepared state.