It's what we expect as shoppers—what's in the food will be displayed on the label.
But a new scientific examination by the non-profit food fraud detectives the U.S. Pharmacopeial Convention (USP), discovered rising numbers of fake ingredients in products from olive oil to spices to fruit juice.
"Food products are not always what they purport to be," Markus Lipp, senior director for Food Standards for the independent lab in Maryland, told ABC News.
USP, a scientific nonprofit that according to their website "sets standards for the identity, strength, quality, and purity of medicines, food ingredients, and dietary supplements manufactured, distributed and consumed worldwide" first released the Food Fraud Database in April 2012.
The organization examined more than 1,300 published studies and media reports from 1980-2010. The update to the database includes nearly 800 new records, nearly all published in 2011 and 2012.
Among the most popular targets for unscrupulous food suppliers? Pomegranate juice, which is often diluted with grape or pear juice.
"Pomegranate juice is a high-value ingredient and a high-priced ingredient, and adulteration appears to be widespread," Lipp said. "It can be adulterated with other food juices…additional sugar, or just water and sugar."
Lipp added that there have also been reports of completely "synthetic pomegranate juice" that didn't contain any traces of the real juice.
USP tells ABC News that liquids and ground foods in general are the easiest to tamper with: Olive oil: often diluted with cheaper oils Lemon juice: cheapened with water and sugar Tea: diluted with fillers like lawn grass or fern leaves Spices: like paprika or saffron adulterated with dangerous food colorings that mimic the colors
Milk, honey, coffee and syrup are also listed by the USP as being highly adulterated products.
Also high on the list: seafood. The number one fake being escolar, an oily fish that can cause stomach problems, being mislabeled as white tuna or albacore, frequently found on sushi menus.
National Consumers League did its own testing on lemon juice just this past year and found four different products labeled 100 percent lemon juice were far from pure.
"One had 10 percent lemon juice, it said it had 100 percent, another had 15 percent lemon juice, another...had 25 percent, and the last one had 35 percent lemon juice," Sally Greenberg, Executive Director for the National Consumers League said. "And they were all labeled 100 percent lemon juice."
Greenberg explains there are indications to help consumers pick the faux from the food.
"In a bottle of olive oil if there's a dark bottle, does it have the date that it was harvested?" she said. While other products, such as honey or lemon juice, are more difficult to discern, if the price is "too good to be true" it probably is.
"$5.50, that's pretty cheap for extra virgin olive oil," Greenberg said. "And something that should raise some eyebrows for consumers."
Many of the products USP found to be adulterated are those that would be more expensive or research intensive in its production. "Pomegranate juice is expensive because there is little juice in a pomegranate," Lipp said.
But the issue is more than just not getting what you pay for.
"There's absolutely a public health risk," said John Spink, associate director for the Anti-Counterfeit and Product Protection Program (A-CAPPP) at Michigan State University. "And the key is the people that are unauthorized to handle this product, they are probably not following good manufacturing practices and so there could be contaminates in it."
Spink recommends purchasing from "suppliers, retailers, brands, that have a vested interest in keeping us as repeat customers."
Both the FDA and the Grocery Manufacturers Association say they take food adulteration "very seriously."
"FDA's protection of consumers includes not only regulating and continually monitoring food products in interstate commerce for safety and sanitation, but also for the truthfulness and accuracy of their labels," the FDA said in a statement to ABC News.
Most recently the FDA issued an alert for pomegranate juice mislabeled as 100 percent pomegranate juice, as well as one for the adulteration of honey.
The Grocery Manufacturers of America told ABC News in a statement that "ensuring the safety and integrity of our products – and maintaining the confidence of consumers – is the single most important goal of our industry," and that their members have "robust quality management programs and procedures in place, including analytical testing, to help ensure that only the safest and highest quality products are being offered to consumers."