You can satisfy pretty much any nutritional need in portable, rectangular form these days: Protein bars, fiber bars, performance bars (whatever that even means), protein and fiber bars… And the FLAVORS, my god. Caramel fudge, mint chocolate chip, strawberry. It’s like ice cream!
Unfortunately, also much like ice cream, these bars can cause pretty unfortunate side effects for some people. If you’ve ever experienced gassiness, cramping, bloating, and general not-okayness in the stomach area after your a.m. fiber bar or post-workout protein bar, it’s normal to feel betrayed and confused. But you’re not alone.
“A lot of these bars with a health angle can have ingredients that can cause people [GI] distress,” Colleen Tewksbury, Ph.D., M.P.H., R.D., senior research investigator and bariatric program manager at Penn Medicine and president-elect of the Pennsylvania Academy of Nutrition and Dietetics, tells SELF.
Cool, it’s not in our heads, so what’s up with that? Here’s what you need to know about the common bar ingredients that could be giving you tummy trouble.
The first culprit: added fiber
The nondigestible type of carbohydrate we call fiber is, in many ways, da bomb. In addition to regulating digestion and helping you poop—as if that wasn’t enough!—fiber slows down the absorption of sugar and cholesterol into the bloodstream, which can help to keep blood sugar levels steady and LDL cholesterol levels lower, according to the Food and Drug Administration (FDA). Fiber intake is associated with many measures of health, and most of us could do with eating more of it.
We all know this. And, the people trying to sell bars know that we know this—so they load ‘em up with fiber. We’re talking 10, 12, or 15 grams of fiber a serving. That’s far above and beyond that of an apple (4 or 5 grams) or slice of whole grain bread (3 grams). In fact, “That’s about half your fiber needs for the whole day,” Beth Kitchin, Ph.D., R.D.N., assistant professor in the UAB Department of Nutrition Sciences, tells SELF. (The Dietary Guidelines recommend getting about 14 g per 1,000 calories in your diet, so around 25 to 35 g for most people.)
Common bar ingredients like oats or nuts can naturally provide a few grams of fiber, but food manufacturers typically use what’s called added fiber to dramatically boost a product’s fiber content. The most popular kind is extracted and isolated from a plant called chicory root. Manufacturers like it because it helps pack a huge hit of fiber without making it taste like mulch. Look out for chicory root, inulin, chicory root fiber, chicory root extract, or oligofructose on the ingredients label, per the FDA. Added fiber isn’t broken out separately in the Nutrition Facts; it’s just included in the total fiber count. So a high-fiber content is your tipoff to look for one of those ingredient names.
And you may have already learned the hard way that as wonderful as fiber is, there is such a thing as too much. Whenever you eat a ton of fiber in one sitting—or just more than you’re used to—you run the risk of messing with your tummy, Kitchin says. Overdoing it on fiber can commonly cause gas, bloating, and cramping, according to the Mayo Clinic.
While this can sometimes happen with naturally fibery foods (like beans), it’s much more likely to happen with these bars because of the super-high concentration of fiber. “[Inulin] is a pretty dense added fiber to begin with, but it really is the huge quantity you’re getting all at once that can cause an issue,” Tewksbury explains. “That amount is a lot for your stomach to handle…Your system just isn’t used to that.”
Another issue specific to these bars: Fiber works best when you have water in your system, Kitchin explains, because it absorbs water to soften things up. When you eat something like fruits and veggies, you naturally get some water with your fiber. But since these bars are pretty dry, if you don’t drink water with them, “You’re going to have this really dry mass sitting there,” Kitchin says.
The second culprit: sugar alcohols
Much like many of us are trying to eat more fiber, a lot of people have cutting down on sugar on the brain. Enter a weird type of carb called the sugar alcohol. (Not the same as the kind of alcohol that intoxicates you, though, hence why your protein bars don’t make you tipsy.)
Sugar alcohols taste sweet, but don’t add to the sugar content and contain fewer calories per gram than real sugar, per the FDA. So food companies often turn to them when they want to make a product that will appeal to people seeking snacks lower in sugar and calories, Tewksbury says. They can be made in a lab from sugars and starches, or extracted from fruits and veggies, where they naturally occur in small amounts, according to the FDA. Look for these eight FDA-approved sugar alcohols on the label: erythritol, hydrogenated starch hydrolysates (HSH), isomalt, lactitol, maltitol, mannitol, sorbitol, and xylitol. It’s up to manufacturers whether or not to include sugar alcohol content under Total Carbohydrate in the Nutrition Facts (unless they’re making a specific health claim about the sugar alcohol), so the only way to know for sure whether something contains sugar alcohol is to scan the ingredients list.
The other reason sugar alcohols are so popular in these products—more so than other sugar substitutes, like sucralose (Splenda)—is that they result in a yummier bar, texture or taste-wise. (If you’ve ever tried to bake brownies or cookies at home using Splenda, you can understand.) “They bake really well and make for a much more palatable product than using sucralose,” Tewksbury explains. Sugar alcohols can also help add bulk and texture, keep a baked good or bar moist, and prevent it from over-browning during baking, according to the FDA.
However, sugar alcohols do come with a not-so-sweet downside when consumed in the amounts found in some bars: gas, bloating, cramping, and diarrhea. How much is too much depends on the person. “It’s hard to say,” Tewksbury explains. “The theory is that a person’s threshold and how severe of a reaction they may get depends on the makeup of their gut bacteria,” a science we’re still just beginning to understand. Some people might have a problem with as little as 5 grams, while other people won’t notice side effects until they hit 15 grams. (It can depend on the type of sugar alcohol; more on that in a minute.) But generally speaking, the more sugar alcohol something contains, the likelier you are to have a problem.
This is thanks to the unusual way sugar alcohols move through your GI tract. Typically during the digestive process, food gets broken down and its nutrients absorbed into the body, leaving primarily waste product (the makings of your next poop) in the colon. But sugar alcohols stay largely intact during the digestive process, so a good amount makes it down to your colon, where it gets feasted upon by the bacteria there, Tewksbury explains. “And whenever bacteria eat, they make gas.” The gas can build up, causing bloating, cramping, and discomfort, or escape in stinky farts. Sugar alcohols can also have the effect of pulling water into the colon, Tewkbsury says, producing the watery avalanche of feces known as diarrhea. (For this reason, small amounts can actually be used to help with constipation, Tewksbury says.)
Some sugar alcohols are more aggravating than others. Generally speaking, the FDA has found sorbitol and mannitol to be the worst offenders, mandating warning labels about the potential laxative effects of “excess consumption” for products containing them. While the increasingly popular xylitol doesn’t require warning labels, they can definitely still cause these issues in many if not most people, Tewksbury says. And there’s evidence that erythritol is less likely to cause GI problems because it’s better absorbed in the small intestine than the other sugar alcohols, so less makes it down to the colon.
The bottom line
“Everyone has a different threshold their body can handle” when it comes to inulin and sugar alcohols, “so the severity of the effects really depend on the individual,” Tewksbury says.
If your beloved bars don’t cause you any issues, there’s no reason to give them up. If they cause you mild gas and you consider that a worthy tradeoff, who are we to stop you? “It’s not dangerous, just discomfort,” Kitchin says. But if you have been experiencing post-bar misery, now you know why.
This doesn’t mean you have to break up with bars for good, though. You can try incorporating your problematic fave into your diet more gradually to help your body adjust. “I tell my patients that any time you try a new product touted as being high in fiber or low in sugar, just be careful and it take it slow,” Kitchin says. In general, it’s a good idea to increase the amount of fiber in your diet slowly, per the U.S. National Library of Medicine. (And again, drink plenty of water.) That can be tricky to do with a super high-fiber bar, so Kitchin recommends starting out with half of one for a few days and seeing how you feel. Same goes for sugar alcohol; GI symptoms are most likely when you’re completely unaccustomed to the stuff and then eat like 20 grams in one sitting. But studies show that with habitual consumption, people’s gut flora can actually adapt to better handle sugar alcohols. There’s not really a magic formula, here: Just have a little at a time, and see how you feel.
Given the number of options out there, though, one pretty easy solution is to try a different variety of bar that has less (or none) of the ingredient giving you an issue. That could mean choosing one with less fiber. After all, the best way to meet your daily fiber needs is by eating a wide variety of naturally fibrous foods, like fruits, veggies, legumes, and whole grains, because of the nutritional richness they offer—consider fibery bars a bonus. Or, try a bar that contains some real sugar instead of sugar alcohols, whether it’s added in (like honey) or naturally occurring (like raisins). It’s hard to remember sometimes in the era of keto and paleo, but sugar has a place in a healthy diet and is not in and of itself something to be afraid of or avoided like the plague. At the end of the day, something that makes you feel like shit is not better for you—even if it’s high-fiber and/or low-sugar.