Protein bars have long been touted as a convenient and healthy snack — a quick fix before a workout or on the go. With packaging that emphasizes their high protein content, they’re often seen as a good choice for maintaining muscle mass and energy. But a new European study published in Scientific Reports (Nature) questions the actual nutritional value of these products.

The study analyzed 1,641 protein bars out of more than 4,600, using a database from the OpenFoodFacts platform. While the study was conducted in Europe, almost half of the products were American, making it relevant to a wider market.

Many of the bars analyzed don’t offer as much protein as consumers might expect. About 19 percent of the products get less than 20 percent of their calories from protein — the minimum value below which the authors don’t consider them to be a significant source of this macronutrient. By comparison, the U.S. Food and Drug Administration (FDA) defines an “excellent source” of a substance as any product that provides at least 20 percent of the daily recommended value in a single serving.

“Protein content alone is not a sufficient indicator of food quality,” explained Dr. Laszlo Abranko, the study’s lead author from the Hungarian University of Agricultural and Life Sciences.

Using a laboratory digestion simulation, the researchers assessed how protein from different types of bars—plant-based, animal-based, or mixed sources—was absorbed. The results ranged widely, from 47 percent to 81 percent. Surprisingly, some of the products with animal protein or soy—traditionally considered “complete” sources—also showed low levels.

The authors believe the reason may lie in the way they are processed and interact with other ingredients in the product, such as fat or fiber. “Even a quality protein bar may not be well-digested if it’s highly processed,” said registered dietitian Eliza Whitaker, founder of Nourished Nutrition and Fitness.

Most protein bars fall into the category of ultra-processed foods — loaded with additives, stabilizers, and artificial sweeteners. A growing body of research has linked regular consumption of such products to an increased risk of obesity, heart disease, and type 2 diabetes.

However, bars can be a convenient option for certain groups — such as people with health conditions that reduce appetite or those taking weight-management medications. “They’re not meant to be a primary source of nutrition, but rather a supplement,” emphasizes Monica Ambern, senior director of nutrition at the International Food Information Council. | BGNES