(FORTUNE Magazine) – Say what you will about American food, at least we Yanks haven't afflicted the world with calamities like haggis, the Scottish staple made of boiled sheep's stomach, or hakarl, an Icelandic offering of putrid shark. In fact, it's hard to think of a down-home American recipe that would warrant inclusion in The Joy of Cooking a Dog's Ex-Breakfast--the obvious title for a collection of demented dishes like haggis. Unless, that is, you happen to know about the human-hair extract in U.S. baked goods, the crushed-insect residue in many of our foods, and the flavorings made with ... something unimaginable.

Those aren't contaminants. They are official ingredients that the food industry rarely tells us about. Some yuck factors are fairly obvious, such as the blue mold spores in Stilton cheese. But most are hidden, since it's perfectly legal for manufacturers to lump additives such as insect extracts under the comforting term "natural" on food labels--or simply omit them (unlike artificial ingredients). How many times have you seen "essence of squashed bug" listed on a food package?

Yet if you scan the label on, say, a container of strawberry yogurt, you may spot "carmine"--a popular coloring concocted from insects. Used to give red, pink, and purple color to everything from ice cream to lipstick, carmine is made from a pigment called cochineal. Cochineal, in turn, is extracted from dried female insects that feed on a cactus found in Peru, the Canary Islands, and other places. The pigment builds up in the insects' bodies; after the six-legged moms deposit their eggs on the cactus and die, their rotting carcasses, along with the eggs and hatched larvae, are brushed off the plants, crushed, and then baked, boiled, or steamed to produce cochineal.

Carmine may not be yummy, but it is GRAS. That's food-industry speak for Generally Recognized as Safe, a classification almost as all-embracing as "natural." But skeptics say carmine can cause severe allergic reactions, and hence should be classified as CRUD--Considered Really Unsafe to Devour. (I just made up that category.) Several years ago the Center for Science in the Public Interest, a consumer watchdog in Washington, D.C., petitioned the FDA either to ban carmine or to require that manufacturers disclose its creepy-crawly source on labels. So far the agency hasn't responded.

If you want to rid your diet of bug extracts, you'll need to avoid not only reddish foods but also many shiny ones. Shellac, made from the excretions of insects, is used to glaze everything from apples to coffee beans. If you get really obsessed, you may starve; blended-in insect remnants are everywhere. The FDA permits a typical jar of peanut butter to contain over 100 bug parts. A can of tomatoes can include one maggot or up to nine fly eggs.

But you'll find stranger things than insect parts if you hack into the American cuisine's heart of darkness. Perhaps the creepiest ingredient is l-cysteine. Sometimes derived from a human body part--to wit, hair--it seems to have come right out of The Mistah Kurtz Cookbook. (It also can be extracted from feathers or produced synthetically.) An amino acid, l-cysteine is used to enhance the stretchiness of dough, which facilitates its rapid processing by machines into cookies, pizza crusts, bread, doughnuts, bagels, and other baked goods.

Discovering whether a product contains stuff extruded from human bodies isn't easy. When I put the question to a spokesman at Interstate Brands, which makes Wonderbread, Hostess, and other baked lines, he said, "I've no idea of the source. We don't use enough l-cysteine to be interested." A Sara Lee spokesman snapped that there was no hair extract in his company's products but declined to say how he knew. A spokesman at Puratos Group, a Belgium-based supplier of bakery ingredients, was friendlier: "Very commonly l-cysteine is from human hair," he conceded, "but I'm 99% sure that ours comes from duck feathers."

Oh, well. Next question: Whose hair do we eat, anyway? Industry experts say most human-derived l-cysteine comes from Chinese women, who, in a case of life imitating O. Henry, help support their families by peddling their tresses to small chemical-processing plants scattered across the People's Republic.

The baking industry's hairy little secret takes the cake for weird, but among all consumables, cigarettes stand out as richest for bizarre ingredients. According to tobacco industry documents divulged in court cases, various brands of cigarettes include cocoa, pine oil, bee's wax, prune juice, cognac, vinegar, beet juice, apple skins, butter, flour, yeast, maple syrup, urea, skatole, and several hundred other additives.

To those with a smattering of chemistry, skatole is the most startling--it is one of dung's key components. (Don't freak: The skatole added to consumables is synthetic.) To flavorists, the fact that cigarettes are spiked with simulated essence of excrement doesn't seem odd at all. At low levels, skatole actually smells nice. Indeed, it is often added to jasmine fragrances and flavorings, says Frank Fischetti, a senior flavor chemist at Wynn Starr Specialty Foods & Flavors in Allendale, N.J.

Similar olfactory paradoxes are at work in perfumes, says Fischetti. Rose-scented fragrances often contain small amounts of civet absolute, an extract from the anal scent glands of civet cats, weasel-like creatures of Asia. Yet "when you taste concentrated civet, it reminds you of fecal matter," he adds. Taste it? "In the old days we got civet from Asia," says Fischetti. "It came packed in water buffalo horns. One of my jobs was to tell if it really was civet. You had to taste it to make sure." (Instruments now do the job.)

Civet was once widely used in meat flavorings, cheese, and other foods. Like skatole, its role is to help blend a mix of flavors or fragrances together. But today a cheaper synthetic version, civetone, has replaced the real thing in most products except high-end perfumes.

One member of the scatological fragrance family hasn't yet been synthetically replicated: castoreum. Extracted from beavers' anal musk glands, it is sparingly used to impart a "smoothing and rounding note" to raspberry flavorings. Which raises an issue that's been crying out for attention for several paragraphs: How did things like beaver excretions find their way into food in the first place? We'll let that one cry itself to sleep; we wouldn't want to spoil your appetite.