What Happens If You Eat Mouldy Food?

"Eating mouldy bread is discouraged. Where can I find the facts that prove this? Are there moulds that grow on bread that are harmless? Some of my patients that survived food shortages in the UK during World War II by eating mouldy bread and other foods insist that such fears about mould are unfounded."
When you eat moldy food, nothing may happen. However there are 2 major reasons why eating moldy food is dangerous.
Such food is likely to be contaminated with mycotoxins (i.e., fungal poisons). Mycotoxin poisoning is primarily through ingestion of contaminated food. The effect of poisoning by mycotoxin is called mycotoxicoses. There are several documented (and probably more undocumented) cases of mycotoxicoses both in human and domesticated animals. Common molds known to produce mycotoxins include Aspergillus, Penicillium and Fusarium.
There is also a high risk of food poisoning caused by bacteria such as Staphylococcus aureus, Salmonella, Clostridium perfringens, Campylobacter, Listeria monocytogenes, Vibrio parahaemolyticus, Bacillus cereus, and Entero-pathogenic Escherichia coli.