Bloating isn’t just about one sketchy ingredient—it’s usually the combo that causes the blow-up. Think: sugar alcohols + high fiber or whey concentrate + gums + prebiotics = the perfect gas grenade. Here’s what to actually watch out for if you're tired of feeling (and sounding) like a whoopee cushion:
🚫 Sugar Alcohols
Maltitol, Erythritol, Sorbitol, Xylitol. These guys sneak into bars as “low sugar” sweeteners—but your gut hates them. They're poorly absorbed in the small intestine, and once they hit your colon, they ferment hard, causing gas, bloating, cramping or worse.
🚫 High-Fiber Additives
Fiber is essential—but too much of the wrong kind can backfire. Once you hit 8–10 g of highly fermentable added fiber in a single bar, discomfort often follows. Chicory root fiber (inulin) is a prime example: inulin is the soluble fiber extracted from chicory root, and it’s rapidly fermented by gut bacteria—great for them, not always for you. The result can be gas, bloating, or cramping, especially if your gut isn’t accustomed to it.
Polydextrose, by contrast, is a synthetic, glucose-based fiber and bulking agent used to add fiber and improve texture while cutting sugar. It’s only partly digestible and partly fermentable, so small amounts are usually fine—but higher doses can still cause bloating or a laxative effect.
Other “stealth” fibers, such as soluble corn fiber or isomalto-oligosaccharides (IMO), behave similarly: harmless alone, but when combined with other ingredients in a bar, their cumulative fermentability can leave you feeling uncomfortably full or puffy.
🚫 Soy Protein Isolate
Harder to digest than dairy proteins. Often over-processed using hexane, and unless organic, may carry pesticide residue. Add in the phytoestrogens (isoflavones) and you’ve got potential hormonal disruption. Some tolerate it fine. But if you're bloated and eating soy bars regularly? Time to reevaluate.
🚫 Low-Quality Collagen or Gelatin
Collagen isn’t a complete protein, and low-grade collagen or non-hydrolyzed gelatin can be hard to digest. Plus, in bars, it often replaces higher-quality proteins that actually build muscle.
🚫 Aspartame & Acesulfame K
Yes, they’re technically “zero-calorie” but even small quantities of these chemical sweeteners can disrupt the gut microbiome, mess with digestion and trigger gas in sensitive people. Some research also questions their impact on mood and metabolism.
The Bottom Line
Want a protein bar that fuels performance without turning your gut into a hot-air balloon? Stick to clean ingredients, complete proteins and brands that actually give a damn about digestion.
(You know... like us.)
