During the Middle Ages, there were several food-related diseases and health issues, some of which were due to the lack of knowledge about food safety, preservation methods, and nutrition. Here are some of the key food-related problems and diseases that people faced during this period:

1. Foodborne Illnesses: Without modern preservation techniques and knowledge of bacteria, foodborne illnesses were common. Meat, dairy products, and even bread could become contaminated with bacteria, leading to illnesses such as salmonella and staphylococcus infections.

2. Famine: Famine was a recurrent problem in the Middle Ages, caused by factors like poor harvests, wars, and climate changes (such as the Little Ice Age). Famine led to severe malnutrition and starvation, weakening populations and making them more susceptible to diseases.

3. Nutritional Deficiencies: Limited diets, especially among the poor, led to nutritional deficiencies. Common issues included scurvy (vitamin C deficiency), pellagra (niacin deficiency), and rickets (vitamin D deficiency).

4. Ergotism: This was caused by consuming rye or other cereals contaminated with ergot, a toxic fungus. Ergotism could lead to symptoms like hallucinations, gangrene, and convulsions. It was sometimes known as "St. Anthony's fire."

5. Alcohol-Related Diseases: While not always recognized as a foodborne illness, excessive consumption of alcohol (often safer to drink than water) could lead to chronic health issues, including liver disease.

6. Parasitic Infections: Poor sanitary conditions and the consumption of undercooked meat led to parasitic infections such as trichinosis and tapeworms.

7. Adulteration of Food: Adulteration of food with cheaper substances was not uncommon, which could lead to health issues. For example, bread was sometimes bulked up with chalk or other inedible materials.

8. Gout: Among the wealthy, who had access to rich diets heavy in meats, alcohol, and sweet foods, gout was a common problem. Gout is a form of inflammatory arthritis caused by high levels of uric acid.

It's important to note that the understanding of diseases and their causes was very different in the Middle Ages compared to modern times. Many ailments were attributed to imbalances of the four humors (blood, phlegm, black bile, and yellow bile) rather than to dietary causes or pathogens, as understood today.