Bone broth contains several compounds that support gut health, primarily by strengthening the intestinal lining, calming inflammation, and helping gut cells regenerate. The key players are amino acids like glutamine, glycine, and proline, along with gelatin, all of which are released when bones and connective tissue simmer in water for hours. That said, while the biological mechanisms are plausible and supported by lab research, no human clinical trials have directly proven that drinking bone broth heals a damaged gut.
How Glutamine Supports the Gut Lining
The intestinal wall is a single layer of cells that replaces itself every few days. Glutamine, the most abundant amino acid in bone broth, serves as the primary fuel source for these cells. It stimulates the growth of new intestinal cells and enhances the action of growth factors that drive that process. Chicken bone broth contains roughly 3.5 milligrams of glutamine per gram of broth, while beef bone broth provides about 2.6 milligrams per gram.
Beyond fueling cell growth, glutamine strengthens the “seals” between intestinal cells. These seals, called tight junctions, are protein structures that control what passes through the gut wall and into the bloodstream. When tight junctions break down, bacteria and food particles can slip through, a phenomenon sometimes called increased intestinal permeability or “leaky gut.” Glutamine promotes the production of multiple tight junction proteins, which helps keep the barrier intact. Research in cell and animal models consistently shows that glutamine supplementation improves gut barrier function, particularly when permeability is already compromised.
Gelatin and the Protective Mucus Layer
When collagen from bones dissolves during cooking, it becomes gelatin. This gelatin is insoluble in the acidic environment of the stomach, so it passes through largely intact until it reaches the intestines, where the higher pH allows it to dissolve and interact with the gut lining.
Animal studies on gelatin-based compounds show they can form a protective film by bonding with mucin, the protein that makes up the intestinal mucus layer. This mucus layer acts as a physical barrier between gut bacteria and the intestinal wall. In mouse studies of colitis, animals treated with a gelatin compound maintained mucus layers similar in thickness and composition to healthy mice, while untreated mice had severely thinned or absent mucus layers. The gelatin essentially helps restore the gut’s first line of defense against bacterial invasion and irritation.
How Glycine Reduces Gut Inflammation
Glycine is the most plentiful amino acid in bone broth, at roughly 3.7 to 4.1 milligrams per gram depending on whether you use beef or chicken bones. It plays a surprisingly active role in calming the immune response inside the gut.
In animal models of colitis, dietary glycine reduced the expression of a key inflammatory signaling molecule (IL-1β) while boosting production of an anti-inflammatory one (IL-10). This shift matters because chronic gut conditions like inflammatory bowel disease are driven by an imbalance between these two types of signals. Glycine also inhibits the release of inflammatory compounds from immune cells, including monocytes, macrophages, and neutrophils. Interestingly, researchers found that glycine’s anti-inflammatory effects may partly work through changes in gut bacteria composition, suggesting it influences the gut environment from multiple angles.
Proline and Tissue Repair
Proline, present at about 2.2 to 2.4 milligrams per gram of bone broth, is essential for collagen synthesis. Your body uses proline to rebuild connective tissue throughout the digestive tract. While this amino acid doesn’t get as much attention as glutamine or glycine, it contributes to the structural repair that a damaged gut lining needs. Combined with the other amino acids in bone broth, proline rounds out a profile that supports both the cells of the intestinal wall and the connective tissue beneath them.
What the Science Actually Proves
Here’s where expectations need to be calibrated. The mechanisms described above come primarily from cell culture experiments and animal studies, often using isolated amino acids or gelatin compounds at controlled doses. No robust human clinical trial has demonstrated that drinking bone broth directly changes the gut microbiome, heals intestinal permeability, or reverses digestive conditions. As gastroenterologist Kenneth Brown has noted, very few scientific studies have been conducted on bone broth itself.
The logic connecting the dots is reasonable: bone broth contains compounds that individually show gut-protective effects in laboratory settings. But the concentrations of these amino acids in a cup of homemade broth may differ significantly from the doses used in research. Lab studies on colitis in mice, for instance, used specific gelatin formulations rather than simmered bones. The leap from “glycine reduces inflammation in a mouse colon” to “bone broth heals your gut” is a larger one than many wellness sources acknowledge.
That doesn’t make bone broth useless. It provides easily digestible protein, hydration, and electrolytes, all of which support recovery when your digestive system is struggling. Gastroenterologists generally view it as a nutritious food rather than a medicine: not a superfood, but not a fad either.
Getting the Most Benefit
If you’re using bone broth to support your gut, preparation matters. Homemade broth gives you more control over ingredients and cooking time. Longer simmering (12 to 24 hours for beef bones, 8 to 12 for chicken) extracts more collagen and amino acids. Adding a splash of vinegar to the water helps pull minerals from the bones.
If you have IBS or are following a low-FODMAP diet, be cautious with store-bought versions. Commercial bone broths often contain onion, garlic, and other high-FODMAP ingredients that can trigger symptoms. Some also include cartilage-derived compounds that may feed problematic gut bacteria in sensitive individuals. Making your own with simple ingredients (bones, water, salt, vinegar) avoids these triggers. The Monash University FODMAP program considers plain bone broth generally well tolerated when prepared without common irritants.
Safety and Heavy Metals
One concern that surfaces frequently is whether bone broth concentrates heavy metals like lead, since bones store these metals over an animal’s lifetime. Research measuring lead levels in both homemade and commercial bone broths found concentrations in the range of just a few micrograms per serving, roughly 2.6 to 4.3 parts per billion in commercial preparations. For context, the EPA’s action level for lead in drinking water is 15 parts per billion. Cadmium levels were so low they fell below the detection limits of lab equipment. The study concluded that risks from heavy metal ingestion through bone broth are minimal.
Aluminum showed slightly higher extraction levels, particularly from pork bones, but concentrations in finished commercial broths remained under 1 part per million. If heavy metals concern you, beef bones tend to release somewhat less lead than pork bones, though the differences were not statistically significant across species.