This anti-neuritic dietary essential (the best prophylactic in the prevention and cure of polyneuritis) is found in abundance in all natural, unprocessed foods. Whole grain cereals, particularly the embryo and coverings of grain, and of the leguminous seeds, such as dried peas, beans, and lentils, contain it in large amounts. The leafy vegetables cabbage, spinach, lettuce, water cress, celery, and parsley are rich in water-soluble B. It is also found in milk and egg yolk, but not in olive oil, butter fat, or any of the animal fats. The foods that do not contain it are polished rice, white flour, starch, white sugar, sirup, and fats. Water-soluble vitamine, it will be recalled, is the food accessory without which beriberi develops in birds, animals, and man.
The well-known investigators Chick and Hume’ are quoted as saying that a real danger may be incurred by too exclusive use of bread made from highly milled wheat; that among groups of people living on restricted diets in which bread made from patent flour formed a large proportion of the total ration, beriberi was very common, whereas people living on similar diets, but with bread made from the entire kernel replacing that made from patent flour, were rarely afflicted. It is well known that in those parts of the world where the poorer classes subsist on a diet restricted largely to polished rice and fish, beriberi is very common, because of a lack of this dietary essential (B) in the food supply. A failure to provide for this important accessory results in malnutrition, followed by nerve degeneration, leading to a sort of paralysis in birds, and beriberi in man, both from the same cause.
Effects of Heat. While dry heat (baking to a brown) seems to be very destructive to vitamines in general, most of the evidence agrees that A and B are not destroyed by heating for considerable periods of time by moist heat at a temperature of 212° F. or lower. Steenbock and Boutwell’ showed that greens, sweet potato, carrot, squash, etc., suffer no appreciable loss of their vitamines by being autoclaved (cooked in a steamer) at fifteen pounds pressure. McCollum and Davis” found that wheat embryo could be heated for one hour at fifteen pounds pressure without apparent loss to the growth-promoting property. McCollum, Simmonds, and Pitz 11 detected little if any diminution when navy beans were heated in moist condition at 120° C. (about 15 pounds pressure) for one and one fourth hours. This shows that the vitamines A and B are stable to moderate heat.