The Shocking Truth About 9 Foods You Thought Were Vegetarian

It's easy to avoid the big no-no's as a vegetarian. Nobody gets confused about where a cheeseburger comes from. However, it's not always safe to assume that certain processed foods on the shelves are vegetarian-friendly. Some labels may be misleading -- or worse: Some foods sneak meat-based ingredients into products you'd never even imagine needing to look at the label for. In the list below, we've compiled the non-vegetarian ingredients you never saw coming.

• Refried Beans
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  Beware of the refried beans! Many of the "traditional" or "original" canned refried beans are made with hydrogenated lard -- or pig fat. Make sure you're looking for the "vegetarian" label if you're avoiding animal-based ingredients.
• Tropicana Heart Healthy Orange Juice
  Flickr:isfullofcrap
  Tropicana's "Heart Healthy with Omega-3" variety actually contains tilapia, sardine and anchovy for those omega 3s. Vegetarians will probably want to stick to plant-based alternatives to get their dose of heart-healthy fats.
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    Parmigiano-Reggiano
    Flickr:aMichiganMom
    Animal rennet -- which comes from mammals' stomach lining -- is often used during the cheese-making process. Parmigiano Reggiano is made with calf rennet, according to the strict specifications and regulations that allow a cheese to be sold as Parmesan. Cheese that does not use animal rennet may or may not include "vegetable rennet" on the label.
  • Marshmallows
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    The s'more staple contains gelatin -- a protein made of skin and bones from pig or cow. Gelatin is used in a variety of foods including gummy bears, Skittles, some yogurts and smoothies.
  • Chips
    amazon.com
    Nutrition labels often don't differentiate between animal and plant-based enzymes. On its website, FritoLay explains that enzymes from pork "are used to develop the cheese in some of our cheese seasonings." Check out the list of FritoLay chips that are free of pork enzymes to make sure you make the right purchase for you.
  • Worcestershire Sauce
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    Worcestershire sauce is relatively well-known for containing anchovies. Look for an anchovy-free brand.
  • Bagels
    Flickr:CLender
    Some bagels -- including Lender's -- are made with the amino acid L-cysteine, which comes from either human hair or poultry feathers. Lender's lists the ingredient clearly on their labels while other companies, including Wonderbread,don't even know which source their ingredient is from, according to a Fortune report.
  • Altoids
    Flickr:Beraldo Leal
    Gelatin again! Because it's used as a thickening agent, gelatin gives gummies and yogurt that jelly-like consistency. However, it also is used as a stabilizing agent in products such as Altoids.
  • Beer
    Flickr:Jirka Matousek
    It's a fairly well-known fact that Guinness beer uses isinglass, or fish bladder, as a fining agent, meaning it removes unwanted leftovers from the brewing process, HuffPost Green reported. Although Guinness does not list the ingredient on the label, minute traces may make it into your glass. Not all beers use isinglass, although others may use gelatin for the same purpose, according to Smithsonian magazine.