Bread
Bread is one of the most basic foods around the world, known as the staff of life. During the Victorian Age, the way bread was made began to change, particularly in urban households. Bread began to be made less in the home and more at a neighborhood bakery. It became a for-profit item, and the earliest vestiges of commercial bakeries began to emerge.
When they did, some manufacturers began to explore ways to increase their profits. Since bread was sold based on the weight of the loaf, with a one pound loaf most common, one way to reduce the cost of manufacture was to reduce the amount of flour, substituting another, hopefully innocuous ingredient, which would maintain the weight without altering the flavor of the loaf.
Many different materials were used in place of some of the flour, including ground bone meal, ground dried beans, Plaster of Paris, and plain chalk. Most popular was alum, which offered the baker several advantages. It was freely available, it was cheap, it was tasteless, and it whitened the bread. It also added more weight since it was heavier by volume than flour.
It also contributed to several health problems, not the least of which was malnutrition. Alum added no nutritional value to the loaves it adulterated and in fact since it led to a reduction in flour – the primary nutritional source in bread – it contributed to malnutrition.
It also caused digestive and gastrointestinal problems which ranged from simple indigestion in healthy adults to severe constipation. In children it could induce chronic diarrhea, which could often in itself lead to dehydration and death. As in the case of Gloucester Cheese, there was no government oversight to ensure the ingredients in bread were what the consumer believed them to be, nor any requirement to inform the consumer that they were not.