If you are interested in what people ate in the past have a browse through this website:

http://www.foodtimeline.org/

It has a huge amount of books and resources from the past organised by year. You can read most of the old articles and books online for free. 19th century diets were vary varied. Judge for yourself how healthy it seems.

An example is this one: TREATISE ON BREAD, AND BREAD MAKING (1837).

There are probably few people in civilized life, who were the question put to them directly - would not say, that they consider bread one of the most, if not the most important article of diet which enters into the food of man.

And this one: The Frugal Housewife, or, Complete woman cook (1803).

This book and the 1807 Rundell, A New System of Domestic Cookery, offer an excellent overview of the English contributions to what has become American cooking. Many of the traditional English recipes found in Mrs. Rundell's work also appear in this volume. But this book does have a most intriguing group of recipes in a brief appendix "Containing Several New Receipts Adapted to the American Mode of Cooking." The recipes listed make fascinating reading: Baked Indian Pudding, An Indian Pudding Boiled, Mush, Buck-Wheat Cakes, Pumpkin Pie, Dough Nuts, To Make Sausage, Blood-Pudding, Cranberry Tarts, To Pickle Peppers, To Pickle Beets, Peach Sweetmeats, Quince Sweetmeats, Green Gage Sweetmeats, A Receipt to Make Maple Sugar, Maple Molasses, Maple Beer, Receipt to Make the Famous Thieves Vinegar, Method of Destroying the Putrid Smell which Meat Acquires during Hot Weather, Spruce Beer out of the Essence, Spruce Beer out of Shed Spruce, Eel Pie, Pork Pie, Raised Pork Pie, Bath Pudding, Pot Pie, Short Gingerbread, Waffles, Crullers and Method of Rearing Turkeys, to Advantage...translated from a Swedish Book, entitled Rural Oeconomy.

I particularly liked this bit "Method of Destroying the Putrid Smell which Meat Acquires during Hot Weather".

As far as what they died of the following charts give a good idea and show the leading causes of death as a percentage of all deaths in the United States, 1900 and 1997. Infectious diseases were a much more important cause of death than now. These probably had little to do with diet apart from contaiminated food and water sources. Charts from here.

Leading Causes of Death, 1997

Leading Causes of Death, 1900*

*Not all States are represented.

Source: Centers for Disease Control and Prevention, National Center for Health Statistics. National Vital Statistics System and unpublished data. 1997.

Perhaps a part of the better-of-people ate like Wiliam Banting (1797-1878)

http://www.second-opinions.co.uk/banting.html

Banting's diet to that date had followed this pattern:

Breakfast: bread and milk for breakfast, or a pint of tea with plenty of milk and sugar, and buttered toast (this was before the invention of breakfast cereals but it is actually very similar to the modern cereal breakfast); Dinner: meat, beer, bread and pastry for dinner; Tea: a meal similar to breakfast; Supper: generally a fruit tart or bread and milk.

At that time, diabetes, obesity and gout distributed mainly among the affluent - not in today's dimensions.

I drink raw milk. I was raised on it. My parents drank it, as did theirs. The problem with raw milk is when it comes from factory-condition farms. Milk borne illnesses started when dairies started opening their operations next door to breweries so they could feed the cows cheap brewery by products. My milk comes from a farm where the goats grass on organic pastures. The guy doing it conducts research with goat milk, and is a biologist and a Phd. I have full confidence that my goat milk is far better for you than anything found in a store. I can even leave it out for a couple of days and still drink it. In the old days they had a name for it "clabbered milk". Try that with store bought milk. If raw milk was inherently dangerous, mankind would have been wiped out thousands of years ago. Pasturized milk is a recent invention. And Pastuer himself never intended for milk to be pasturized. He invented it for beer and wine. He was against Pastuerizing of milk.

Depends if you were rich or poor. Poor populations lived off cabbage and potatoes.

Death rates were in a large part due to infant death and death in childbirth. Childbirth used to be a very dangerous business indeed. Untreated infections was another problem. Things weren't sanitary and no one knew they should be for most of that time period. Disease spread quickly for the same reason. Vaccines weren't invented until towards the end. Some older people alive today still suffer disfigurement wrought by polio in their childhood. Starvation probably got some people. There were no food stamps! Plus there was war in some parts which is always a problem. THese kinds of things make it hard to use death rates as an indication of overall health of a population. We can't say for sure how overall health compares then until now. I could see that maybe with some populations being too poor for decent tasty food and not having access to enough hunting and fishing, they could have eaten even more poorly than SAD. And people then had even less knowledge about nutrition. But the difference is they probably ate that stuff because it was all they had or they would starve. Now, most of us have choices.

Table sugar usage on a large scale extends far before the 19th century. I'm sure they had recipes for all kinds of desserts.

People died of many things. Often foodborne illness from raw milk. See this article for a blunt look at that issue.

http://www.slate.com/id/2260389/

My great great grandmother died in 1895 at age 56 of diarrhea, her obituary stated "Deceased had been ailing for some time and death seemed to have been caused by a general breaking down of the constitution." She was not poor. Her husband, my g-g grandfather, was a pretty well to do farmer in Kansas. He homesteaded 160 acres of very good land in 1871. I think it was an intolerance to wheat. All the conditions below appear to originate with consumption of wheat and/or other grains.

Digestive disorders that may cause chronic diarrhea include: Inflammatory bowel disease, Crohn's disease, Ulcerative colitis, Celiac disease, Irritable bowel syndrome, Diabetic Diarrhea, Food intolerance, Lactose intolerance, Inflammatory bowel disease, Celiac disease, Sprue, Ulcerative colitis, Lactase deficiency, Food allergy,