They seem as American as apple pie and are an inextricable part of a ballgame or summer barbecue, but not everything about the hot dog is all that savory. In fact, as might be expected from a uniformly-shaped tube of meat sold by the billions annually, the hot dog is one of the least natural and least healthy foods that frequent the American plate. And there are plenty of secrets that hot dog companies would rather you not think about when enjoying a dog when warm weather hits.

Often made with a mysterious blend of meats and other ingredients, hot dogs are one of those things that you will like less and less the more you learn how they are made. So fair warning, reading ahead may knock your love for the hot dog down by seven notches.

And sorry to further burst the hot dog bubble, but they are decidedly not American in origin. According to History, hot dogs were invented in Germany, almost certainly in Frankfurt (yes, thus the name "frankfurter," and the same is true for the hamburger which was first made in Hamburg, Germany) as far back as the late 1400s.

If you are still a hot dog fan after reading on, take a look at We Tasted 8 Hot Dog Brands & This Is the Best.

(Plus, if you're looking for a burger be sure to skip the 8 Worst Fast-Food Burgers to Stay Away From Right Now.)

These days, lots of hot dogs are made with cellulose casings—the same plant-based material found in paper, cardboard, and other materials, reports Science Direct—and are usually removed prior to the packaging of the franks. But if you buy hot dogs labeled as "natural," they will have casings made from animal intestines, according to the National Hot Dog and Sausage Council. Cleaned and processed intestines, sure, but intestines nonetheless.

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OK, so we all know the hot dog is hardly a health food, but when it comes to the sodium of it all, these meat tubes are flagrantly bad for you. For example, a single 150-calorie Hebrew National Kosher Beef Frank contains 450 milligrams, or 20%, of your daily recommended sodium intake. A 170-calorie Ball Park Bun Size Beef Hot Dog has 480 milligrams of sodium. And a 110-calorie Oscar Mayer Classic Uncured Weiner has 420 milligrams of the stuff.

According to Marketplace, meat is often playing only about 50% of the role in your hot dog. That's because, according to USDA regulations, hot dogs may contain up to 30% fat, 10% water, and 3.5% "non-meat binder" such as cereals or dried milk. Do the math, and that's just under 44% of a hot dog accounted for by ingredients other than meat.6254a4d1642c605c54bf1cab17d50f1e

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If your hot dogs bill themselves as "all-beef franks" or some other equally direct language, you can count on them containing only beef. (You can't count on only beef in there, to be clear, just that beef will be the only meat.) However, if not billed as such, you can expect hot dogs to contain beef, chicken, turkey, and pork all ground together and jammed in there with sodium phosphate, potassium lactate, and so forth.

Sodium nitrate is not good for you. According to WebMD, this common preservative has been linked to the development of heart disease and diabetes, among other maladies. But sodium nitrate is very good at keeping hot dogs from spoiling by preventing bacterial growth, and it even gives them an artificially "healthy" pink look, according to Inverse. Which, when you think about it, shouldn't be the comfort that it is, because none of the base ingredients used to make up a hot dog were naturally pink.

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According to a TIME story from a few years back, hot dogs all too often contain more than mechanically separated meat, water, salt, and other perhaps unsavory but still expected ingredients. Among the untoward items found in American hot dogs have been insects, human hairs, part of a hypodermic needle, a razor blade, bits of glass, plastic, and rubber, and the list goes on.

Not only are there many meats used in many brands of hot dogs, but they are often meats that would not have been considered suitable for use in other products. According to Business Insider, "After the steaks, chops, breasts, ribs, thighs, hams, tenderloins, and briskets are removed, there's a fair amount of gristle, fat, and offal remaining on a butchered animal, and early on, people realized this could be put to good use." Euphemistically termed "trimmings," much the meat that ends up in hot dogs started off as "lower-grade muscle trimmings, fatty tissues, head meat, animal feet, animal skin, blood, liver and other edible slaughter by-products." All of these are made into a sort of "meat batter" and precooked to stamp out any bacteria. Yum, pass the mustard.

READ MORE: What Happens to Your Body When You Eat Hot Dogs

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