Can Too Much Protein Cause Gas?

Common Culprits: It Might Not Be the Protein Itself

In many cases, the protein fart problem has less to do with protein and more to do with the ingredients that often accompany high-protein foods and supplements, says Elena Ivanina, DO, a New York City–based gastroenterologist and the founder of the Center for Integrative Gut Health.

Here are some common culprits.

Dairy

Many protein powders are made of whey or casein, both milk-derived proteins that may also contain lactose, Dr. Ivanina says. About 70 percent of the global adult population has some degree of lactase deficiency, a condition that causes insufficient levels of the enzyme lactase.

Sugar Alcohols and Added Fibers

Protein bars may also contain ingredients that are notorious for causing digestive upset.

“This is a really important piece of the puzzle,” Gaffen says. “When someone tells me they feel gassy after eating a protein bar, I don’t jump straight to the protein, I look at the ingredient list. Often, it’s these artificial sweeteners or specific types of added fibers driving the symptoms,” she says.

Added fibers can also be problematic. Ingredients like chicory root, inulin, fructooligosaccharides (FOS), and maltodextrin are commonly added to protein bars to boost fiber content. But they can trigger bloating and gas, especially in people with irritable bowel syndrome (IBS), Ivanina says.

“Studies show that inulin tolerance thresholds can be as low as around 10 grams per day, but many protein bars contain up to 15 grams per serving,” Ivanina says.

Low Carbohydrate Intake

With a strong focus on protein, some diets overlook carbohydrates, which can absolutely play a role in gas and bloating, according to research. Low carbohydrate intake — including fermentable carbohydrates like fiber — may slow digestion and contribute to constipation, giving gut bacteria more time to ferment food sitting in the colon. At the same time, lower carbohydrate intake can shift the microbiome toward more protein fermentation, producing smelly gas.

“In that sense, you can see a pattern of what people describe as ‘gas-producing constipation,’” Gaffen says.