The Plague, as well as any number of awful diseases, dysentery was relatively common. Medicine and surgery was much less understood than it is today, although contrary to popular belief, the Catholic Church was funding medical and scientific research, rather than suppressing it. Contrary to popular belief, peasants and commoners actually had really good teeth, as they commonly brushed their teeth with salt and more importantly clove, which has lots of benefits for teeth health. The real problems were mostly related to lack of proper disease prevention. Not to mention warfare, where you were likely to die a slow, painful death from wounds and/or disease or infection, rather than a quick death on the battlefield. Interestingly, it was actually the upper classes which were in poor health, mostly due to diet because they hate things like white bread and consumed far more sugar than the lower classes. If you were a peasant, foods such as Salmon, Brown Bread, and lots of greens were available, which were all much healthier. This is because you had to go through the effort to actually make food unhealthy, for instance white bread took considerably more time to mill because you have to remove the outer hull, which contains most of the nutritional content. If you poor, the meat cuts that were available were usually offal, which are high in minerals, and are generally healthier. The upper classes were the only ones who could generally get fat, so you really had to pay to eat unhealthy food, while the opposite is true today. Any number of chronic illnesses would go untreated, and they likely had no way of treating conditions such as arthritis. Generally speaking, people were shorter than today, but not by much, and that only is really only in lower class folk, while the English royalty were known to have been exceedingly tall, with Richard the Lionheart being a staggering 6’6. Famine would likely only occurred during war if a campaigning army acquired all the local supplies, because farmland was generally extremely fertile.