We've all heard it. "Eat organic and natural food, exercise regularly, and you'll be nice and healthy without any of that artificial modern medicine."
Well, medieval people ate nothing but organic and natural food, and they certainly were not couch potatoes in front of the TV or behind the wheel of the car, yet their life expectancy was probably somewhere around 50 or 60. They would have loved modern medicine.
But how about healthy eating? All natural, no processed foods. Let's start with "organic." This is a formal category, meaning food grown without chemical fertilizers or pesticides, without giving animals things like growth hormones. Because medieval farmers did not have chemical fertilizers or pesticides, much less have any artificial growth hormone to bump up their cows' milk production, they were certainly organic farmers by today's standards.
Many people (including me) prefer not to eat chemicals that have been sprayed on our food and prefer organic for that reason for fruits and vegetables where you eat the outside. But there's a reason those chemicals came in originally. With modern fertilizers, plants grow much better. Drive by a corn field and notice how much smaller the plants are in the corners, where the fertilizer-spreader didn't reach. With modern pesticides, pests destroy a smaller proportion of the crop.
Organic foods, as I'm sure everyone has noticed, are more expensive because the yield is lower, even with organic farmers hand-picking off bugs and sprinkling nasturtium flowers around (to say nothing of more labor intensive…). The massive famines around the world that were feared back in the 1960s never happened because of chemical fertilizers and pesticides. (Though the population has now about caught up with possible production. Better distribution would help a lot, but that's a separate discussion.)
How about "natural"? This word actually has no defined meaning for food. Okay, this apple was grown "naturally," in that it was grown on a tree, but there's no requirement there of organic. It doesn't show any sign of scale or of little wormy holes, so in fact it is probably not organic. Medieval food, however, it's safe to say, was all produced "naturally."
How about that healthful exercise? For medieval people to go anywhere, they walked or rode on a horse, which, as any rider will tell you, is a lot more energetic than riding in a car. Peasants spent their days in hard physical labor. Aristocrats traveled a lot. And think about running up and down stairs in a castle all day. Monks were about the only people with a sort of sedentary life style, and some monastic orders stressed manual labor, so the monks might be out there working their own fields (rather than having peasant tenants) and eating nice raw turnips for lunch. A lot more medieval people were physically worn out by their 50s than had their lives extended through exercise.
So making wise food choices and getting appropriate exercise is good. But don't think that eating and working like a medieval peasant is going to make you live a long and healthy life.
(And don't even get me started on the Paleo Diet.)