Fake ingredients, deceptive labeling, cheaper food substitutes—sounds like something you’d expect from a fast food meal, right? Turns out, you could encounter food fraud with many of the everyday items you toss into your grocery cart.MORE: Eight Ways to Make Grocery Shopping More SanitaryThat’s because inferior—and sometimes unhealthy—ingredients in our food has reached an all-time high, according to researchers at the U.S. Pharmacopeial Convention (USP). In the last two years, the USP added nearly 800 items to their food fraud database. Everything from lemon juice to olive oil to seafood could be a big phony, based on their findings.So what exactly is food fraud?“It’s defined as the dilution or substitution of a food ingredient without the knowledge of the purchaser, typically for economic gain by the manufacturer, so one does not get the quality or quantity that they think they are getting,” explains Markus Lipp, Ph.D., senior director for Food Standards at the USP.In other words, it’s false advertising at its finest.MORE: The Psychology of Food AdvertisingThe reason manufacturers do this is simple: They can make more money. In some cases, they substitute a cheaper product for what you think you’re buying. In other cases, they add fake—and just to be clear, unlisted—ingredients to make their product look more natural, which is ironic because these additives are anything but the real deal.Not only do we get ripped off financially, but this faux food could be making us sick. “It’s a real health risk,” says Lipp.Take milk, for example. There was a major case in 2008 where melamine, a chemical found in nitrogen that is used to make plastics, was added to infant formula in China. That deceptive act resulted in several thousand babies falling ill. This U.S.-banned ingredient was also discovered in dog food, causing hundreds of pets to wind up sick or dead.Fish is another big culprit. Here, a more expensive species is substituted with a cheaper one. “If you have a whole fish, it’s obviously easier to identify, but if you have a fillet, it can be much more difficult,” explains Lipp. This bait and switch (if you’ll pardon the pun) is not only deceptive, but it could also cause food poisoning, he notes.MORE: Natural Relief for Upset StomachsLuckily, not all manufacturers are unscrupulous.”We can rest assured that most of our food is safe,” says Lipp. “However, it’s not the case by accident. This requires the vigilance of the FDA to look out for consumers and make sure products are pure.”Outside of putting your trust in the FDA, stepping up your consumer smarts is the best way to protect yourself. That means taking a close look at what you’re actually getting, buying from trusted manufacturers (instead of random discount sites online) and opting for whole foods whenever possible.“If I buy whole black pepper, it comes in pepper kernels,” explains Lipp. “If it is adulterated, I would see that immediately. But if I buy ground black pepper, I may not see it.” That’s because the closer you come to the original product, the easier it is to trust your food and identify any suspicious ingredients.MORE: Are You Getting the Right Kind of Gorgeous Greens?Another way to guard against food fraud is to tap into your common sense. “If a product looks too good to be true or is too cheap to be true—like extra virgin olive oil at half the price of the others on the shelf—then there’s a chance it has some fraudulent ingredients,” adds Lipp.Are there certain products that are guiltier than others? Absolutely.To help you navigate the grocery aisles with more certainty, check out our gallery on the most common food frauds.