In ideal circumstances a fairly large proportion of a given quantity of bread is digested in the mouth. Starch or carbohydrate is quite incapable of absorption until it has been rendered soluble, and this is effected by the action of saliva, which converts it first into dextrin and subsequently into maltose. Pavlov demonstrated that the chewing of fresh moist bread produced no secretion of saliva worth mentioning, but dry bread caused the saliva to flow in large quantities. Stale bread, crust of bread, toast, zwieback (double-toasted bread), and plenty of biscuit compel fairly prolonged mastication with plenty of saliva, while soft bread is usually bolted with no production of digestive juice of any consequence.

On reaching the stomach this digestion of the starch by saliva still goes on until it has been neutralised by the outflow of gastric juice in from half to three-quarters of an hour, and then the protein is attacked by the pepsin and hydrochloric acid. Bread provokes a secretion of five times more pepsin than an equivalent quantity of milk, and four times more than meat, but a much smaller quantity of hydrochloric acid so as to interfere as little as possible with the alkaline saliva. Gastric juice is only able to digest proteins, and in about two hours and a half a slice of bread is ready to leave the stomach.

The various digestive fluids of the intestine soon complete the digestion of the starch and protein and the small quantity of fat contained in bread, and then absorption into the blood takes place. Up to this point there is practically no difference between white and wholemeal bread, but the superiority of the former now becomes apparent. It is easy to understand that no matter how well digested an article of diet may be, it is quite incapable of nourishing the body until it has been absorbed, and in this connection white bread is paramount, for only 3 per cent. of its carbohydrates, 20 per cent. of its proteins, 25 per cent. of its mineral matter, and 4 1/2 per cent. of its total solids escape absorption - even when it is given alone. When mixed with other foods, for example milk, a very much larger proportion is utilised for the nutrition of the body. When we compare these really excellent results with wholemeal, we find that 6 per cent. of its carbohydrates, nearly 30 per cent. of its proteins, over 50 per cent. of its mineral matter, and 14 per cent. all told of its total solids are actually unabsorbed.

To a very large extent these inferior results are due to the presence of so much cellulose or indigestible woody fibre which prevents the digestive fluids from dissolving the nutrients present, but whether this is the sole reason or not, it is quite certain that, weight for weight, white bread is infinitely more nutritious than wholemeal bread or any far-away imitation of it. Standard bread, therefore, while containing a slightly larger proportion of nutritive ingredients, cannot be nearly so well absorbed as white bread, and its available nutritious power is decidedly less than that of the latter.

Not only is this the case, but the really valuable feature possessed by wholemeal bread, viz. its power to counteract the tendency to constipation, is practically absent from the standard bread, which makes a point of excluding most of the bran on the plea that it is innutritious.

In view of these facts, efforts have been made to manufacture bread containing a much larger proportion of digestible material, and the most successful attempt so far as I am aware is Maltweat, made by Winter of Birmingham. Instead of the 47 per cent. of insoluble carbohydrates of white bread, it only contains 10 per cent., while in lieu of 6 per cent. of soluble carbohydrates it possesses no less than 53 per cent. in the form of maltose and dextrin, i.e. nearly nine times the quantity contained in white or standard bread. Its value is also enhanced by its small quantity of moisture - quite 10 per cent, less than any other bread on the market. Hardly less important, however, is its content of protein, which is not only at least 10 per cent, higher than in the best quality of white or standard bread, but is practically all capable of immediate absorption, as in large measure it is not surrounded by an insoluble covering of cellulose. It is therefore not only superior in nutritive power to any other bread, but much less energy is dissipated in digesting and absorbing it, so that its value to the human economy is unexcelled.