General Mills uses pea protein to make its Lärabar Alt bars. Lärabar customers ‘focus on health, fitness, and the environment,’ a company spokeswoman says.

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Many consumers associate protein with benefits such as weight loss and greater energy. Food manufacturers are increasingly adding pea protein, made by processing yellow peas, to a variety of foods to pack a greater protein punch.

So Delicious

So Delicious says it added pea protein to almond milk and other products because it wanted to add a vegetable-based protein to appeal to people avoiding meat.

A lowly legume is getting more attention from food manufacturers who want to capitalize on consumers’ clamoring for more protein.

Pea protein—yellow peas that have been processed to remove carbohydrates and leave the protein—is being added to baked goods, snack bars, drinks and cereals that aim to be protein rich while also appealing to people looking for vegan, gluten-free or soy-free products.

Experts say Americans eat more protein than their bodies need. Still, many people are looking to consume more because they associate protein with good health. Currently, soy-protein isolate—soy beans processed to remove carbohydrates and fat—is the most common ingredient added to boost protein content in foods not naturally rich in the nutrient.

Some consumers are allergic to soy. Also, most soy bean plants grown in the U.S. are genetically modified, a turnoff for some consumers. While many health advocates say eating genetically-modified plants appears to be safe, some say foods containing such organisms should be labeled as such. Retailer Whole Foods recently announced that by 2018 all products in its North American stores that contain “GMOs” must say so on the label. (Why 5 more years? They have stores in Europe and Europe has banned GMO’s)

So Delicious Dairy Free, a maker of dairy-free foods, added pea protein to its So Delicious Almond Plus Beverage last year to increase the protein content. More recently it added pea protein to a Greek almond-milk yogurt and frozen almond-milk desserts.

Companies say pea protein has a fairly neutral flavor, making it ideal to add to other foods.

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Soy-protein isolate, made from soybeans, is widely used to add more protein to various foods. But some people avoid soy because of allergy, digestive and other concerns.

General Mills Inc.’s GIS -2.44% new Lärabar Alt bar, with 10 grams of protein, uses pea protein. Other bars made by the company including Fiber One Protein and Nature Valley Protein include soy-protein isolate. Lärabar consumers want food with “recognizable and carefully selected ingredients,” says a General Mills spokeswoman.

A complete protein is one “that provides all the nine amino acids that our body needs,” says Kristin Kirkpatrick, a dietitian and wellness manager at the Cleveland Clinic Wellness Institute.

Animal proteins are a source of complete protein, but plants can also provide complete protein when paired with carbohydrates like rice, she says. Pea protein is a good source of amino acids, she says.

Eating soy or peas stripped of almost everything but protein isn’t as healthy as eating the original food with all its vitamins, minerals and fiber, says Ms. Kirkpatrick.

Write to Sarah Nassauer at sarah.nassauer@wsj.com

A version of this article appeared April 9, 2013, on page D2 in the U.S. edition of The Wall Street Journal, with the headline: LABEL DECODER | Protein Additives.