We all know the obvious culprits.

Steak? Definitely not vegan. Cheese? No debate there. But the sneaky stuff? That’s where things get complicated—and, if I’m being honest, kind of annoying.

I remember picking up a loaf of multigrain bread at a grocery store in Portland. Organic, seeded, no eggs or dairy in sight. I didn’t think twice. Then I spotted L-cysteine buried in the ingredient list. Quick search: derived from duck feathers.

That was the moment I realized how wild the food industry can be. Since then, I’ve been tracking the silent invaders—the animal-based ingredients quietly showing up in things you'd assume were plant-friendly.

Here are 10 of the most surprising ones I’ve come across. Some might be familiar, others might blow your mind. Either way, they’ll change how you read a label.

Let’s kick off with the one that launched me down this rabbit hole: L-cysteine.

This amino acid is often added to bread, pizza dough, pastries, and even some frozen meals. Why? It helps soften dough and extend shelf life.

Sounds harmless until you find out it’s usually derived from duck feathers or human hair. Some synthetic and plant-based versions exist, but companies rarely clarify the source.

When I found this in a bagel I’d been eating for weeks, I actually called the bakery. The woman on the phone laughed nervously and said, “Oh yeah, that’s a weird one, right?”

Yep. Weird enough that I switched to brands that explicitly state “vegetarian-sourced” on the label.

Ever bite into a candy with that high-gloss shine? That glossy finish likely comes from shellac—a secretion from the lac bug.

Yes, bug juice.

It’s used in candies like jelly beans and chocolate-coated nuts, and even on apples to make them look fresher. But it’s not just food. You’ll also find shellac in furniture polish and nail products.

What’s wild is how normal this is. It’s FDA-approved, considered “natural,” and not usually flagged in allergen lists. But if you're avoiding animal byproducts, this one’s a deal-breaker.

This one feels like a linguistic prank.

You’d think “non-dairy creamer” means dairy-free, right? Not necessarily.

Many powdered creamers and processed foods labeled “non-dairy” still contain casein—a protein derived from milk. They get away with it because “non-dairy” legally means it lacks lactose, not that it’s entirely milk-free.

I used to load up on non-dairy creamers in hotel rooms, assuming I was in the clear. Then I learned that casein can still trigger dairy allergies—and it’s definitely not vegan.

These days, I either travel with oat creamer or stick to black coffee. Trust issues run deep.

Carmine is what gives that rich, red hue to many cosmetics and candies. Sounds fancy, but here’s the reality: it comes from crushed cochineal beetles.

About 70,000 insects are killed to produce just one pound of carmine dye.

I learned this the hard way when I bought a “natural” lipstick online, only to find out it contained “cochineal extract.” It was marketed as clean, cruelty-free, and vegan-friendly. Clearly, someone skipped a few steps.

As noted by entomologist Christopher Kline, “Cochineal dye is a centuries-old coloring agent, but its use in modern food and cosmetics often surprises people who expect their products to be insect-free.”

Look for safer, plant-based colorants like beet juice, paprika extract, or synthetic Red 40 (though the latter has its own controversies).

This one sounds like something out of a wizarding school. But no magic here—just fish guts.

Isinglass is made from the dried swim bladders of fish, mostly sturgeon. It’s used as a clarifying agent in beers and wines, especially traditional British ales.

Here's the kicker: it's not listed on most labels. So unless you check with the brewery or use a site like Barnivore, you’d never know.

I once brought a bottle of red to a vegan dinner party. Mid-toast, someone pulled up the brand online and—yep—isinglass. We opened a backup bottle of boxed wine instead. Lesson learned.

Stearic acid is a fatty acid found in soaps, shampoos, detergents, and cosmetics.

It can come from plants or from animal fats like tallow. And unless the brand explicitly says “plant-based,” you have no idea which one you’re using.

This is backed by experts like chemical toxicologist Dr. Annette Sharp, who noted in an interview with Cosmetic Science Today, “Without proper labeling, the origin of common cosmetic ingredients remains a mystery to most consumers.”

I switched to a bar soap from a small vegan brand recently—made with coconut-based stearic acid—and it’s honestly better than the generic stuff I was using before. Sometimes being picky pays off.

Glycerin is everywhere. Chewing gum, toothpaste, lotion, cough syrup—if it’s smooth, sticky, or sweet, there’s a chance glycerin’s in there.

Like stearic acid, it can be made from plants or animal fat. And again, most labels don’t tell you which.

It took me a while to figure out why my “vegan-friendly” mouthwash wasn’t certified vegan. Yep—glycerin of unknown origin.

Now I either look for “vegetable glycerin” or shop from brands that are upfront about their sourcing. Once you spot this one, you’ll see it everywhere.

Lanolin is a greasy substance secreted by sheep to protect their wool. After shearing, it’s extracted, purified, and used in lip balms, lotions, nipple creams, and even some vitamin D supplements.

Sounds kind of wholesome—until you look into how sheep are treated in the wool industry. I’ll spare you the details, but let’s just say it’s not all rolling hills and happy bleats.

A friend of mine who runs a vegan skincare business once told me, “Lanolin is like the milk of skincare—everyone uses it until they realize where it comes from.”

These days, there are tons of solid alternatives like shea butter, cocoa butter, and candelilla wax. Bonus: they smell better too.

We mostly associate whey with muscle bros and protein shakes. But it’s sneakier than that.

Whey—a byproduct of cheese-making—is used in everything from chips to crackers to baked goods. It adds a bit of protein and gives processed snacks a longer shelf life.

I once found whey listed on a bag of “veggie chips.” The irony was not lost on me.

Nutritionist Lisa Moseley explains, “Whey is cost-effective and blends well into processed foods, making it a favorite among manufacturers looking to boost protein content without changing texture.”

Moral of the story? Even if something sounds plant-based, the label tells the truth.

Let’s wrap with one that’s both helpful and misleading: Vitamin D3.

It’s often added to cereals, juices, and supplements. But most commercial D3 is derived from—you guessed it—lanolin from sheep’s wool.

If the label says “Vitamin D,” it’s almost always D3 unless noted otherwise. And unless it says “vegan D3” or “from lichen,” it’s animal-based.

You can opt for Vitamin D2, which is plant-derived, but it’s not as effective at raising blood levels of D. So if you're supplementing, look for vegan D3—yes, it exists and it works.

Living a vegan or plant-based lifestyle isn’t about perfection. It’s about awareness.

The truth is, you could spend hours cross-checking labels, emailing companies, and scanning ingredients like a detective on a mission. And still miss something.

But each time you learn about a hidden ingredient, you’re a little better equipped. A little more intentional. And a little more aligned with the values that matter to you.

For me, that’s the real goal—not perfection, but progress.

So next time you’re shopping, keep your eyes open. The label might surprise you. But knowledge? That’s power. And power leads to better choices.

One label at a time.